Marginal Curves Research Articles

Flapping states of an elastically anchored plate in a uniform flow with applications to energy harvesting by fluid-structure interaction

Linear stability analysis of an elastically anchored flat plate in a uniform flow is investigated both analytically and numerically. The analytical formulation explicitly takes into account the effect of the wake on the plate by means of Theodorsen's theory. Three different parameters non-trivially rule the observed dynamics: mass density ratio between plate and fluid, spring elastic constant, and distance between the plate center of mass and the spring anchor point on the plate. We found relationships between these parameters which rule the transition between stable equilibrium and fluttering. The shape of the resulting marginal curve has been successfully verified by high Reynolds number numerical simulations. Finally, the limiting case corresponding to a simply supported rigid rod is also analyzed and the resulting flapping instability traced back to a simple resonance condition. Our findings are of interest in applications related to energy harvesting by fluid-structure interaction, a problem that has recently attracted a great deal of attention. The main aim in that context is to identify the optimal physical/geometrical system configuration leading to large sustained motion, which is the source of energy one aims to extract.

Better product at same cost, lower sales and lower welfare

We consider a high-quality dominant firm facing a low-quality competitive fringe. We show that the dominant firm's quantity is (weakly) increasing in its quality if and only if its marginal cost (weakly) exceeds that of the fringe; otherwise it is strictly decreasing in quality. This result is driven by the fact that a quality increase causes the marginal revenue curve to rotate clockwise, rather than shift outwards, and at a height equal to the fringe firms' marginal cost. This fact, combined with the dominant firm's MR=MC condition, determines the result. For closely related reasons, the effect of a quality increase on consumer welfare also depends on the relationship between the costs. It is possible that all consumers are (weakly) better off, that some are better off and some worse off, or that all are (weakly) worse off. We also consider several extensions and variations of the model.

Better Product at Same Cost, Lower Sales and Lower Welfare

We consider a high-quality dominant firm facing a low-quality competitive fringe. We show that the effect of an increase in the dominant firm's product quality on its equilibrium quantity depends on its marginal cost relative to that of the fringe firms. The dominant firm's output increases in its quality when its cost exceeds that of the fringe, is independent of its quality when marginal costs are equal, and decreases in its quality when the dominant firm's cost is lower than that of the fringe. An increase in the dominant firm's quality does not cause a parallel shift in its residual demand, but rather causes it to pivot. This, in turn, causes its marginal revenue curve to rotate clockwise, rather than shift outwards, at a height that we show to be equal to the fringe firms' cost. This fact, combined with the dominant firm's MR=MC condition, determines the result. For closely related reasons, the effect of a quality increase on consumer welfare also depends on the relationship between the costs. The sign on consumer welfare is ambiguous. It is possible that all consumers are (weakly) better off, that some are better off and some worse off, or that all are (weakly) worse off. We also consider several extensions and variations of the model.

A Kind of Classification Algorithms of Data Mining and Quantitative Analysis

C4.5, Bayesian network and Sequential Minimal Optimization (SMO) are three typical classification algorithms in data mining. Using cross-validation method with 10 folds get analysis and calculation results of the experiments for the three classification algorithms in the same training set and test set. The main metrics include accuracy, precision, speed, robustness, scalability and comprehensibility, we use margin curve show these. It provides a theoretical and experimental basis for users to select a proper classification algorithm with different training sets in quality and amount.

Invasive Micropapillary Carcinoma of the Breast: MR Imaging Findings

ObjectiveTo analyze the magnetic resonance (MR) imaging findings of invasive micropapillary carcinoma of the breast.Materials and MethodsMR images were retrospectively evaluated in 14 patients (age range: 37-67, mean age: 49 years) with pathologically confirmed invasive micropapillary carcinoma of the breast. The enhancement type (mass/non-mass), shape, margin, contrast enhancement, and time-intensity curve pattern on the dynamic study were correlated with the histopathologic features. Associated findings, such as edema, nipple change, skin change and enlarged axillary lymph nodes were also studied.ResultsThe most common features of the masses were irregular shape (12 of 14 patients, 85.8%) and irregular or spiculated margin (11 of 14 patients, 78.7%). The contrast enhancement was heterogeneous in 11 patients (78.7%), rim enhancement in 2 cases (14.2%), and homogeneous in one patient (7.1%). The predominant kinetic pattern was rapid increase (14 of 14, 100%) in the initial phase and washout (11 of 14, 78.7%) in the delayed phase. Associated non-mass like enhancement was shown in 4 patients, representing ductal carcinoma in situ. MR imaging helped detect additional sites of cancer other than the index lesion in 3 patients (21.4%). Enlarged axillary lymphadenopathy was identified in 7 of the 14 patients (50%).ConclusionInvasive micropapillary carcinoma appears as a mass with an irregular shape, irregular or spiculated margin and heterogeneous enhancement on MR imaging. Though these findings are not specific and are also observed with other breast malignancies, invasive micropapillary carcinoma frequently showed multiple lesions, accompanying non-mass enhancement and axillary lymph node enlargement.

A criterion of similarity and transition to turbulence for electric arc flows

A method is suggested for determining the similarity criterion and the criterion of transition of an electric arc flow in a plasmatron channel from a laminar regime to a turbulent one (equivalent Reynolds number) that does not require using any reference temperature. Application of this method to the available experimental data on the transition to turbulence demonstrates its correctness and efficiency. The critical value of the proposed similarity criterion corresponding to the boundary of the transition from a laminar regime to a turbulent one has been revealed. A marginal curve separating the regions of the laminar and turbulent regimes of the plasma flow has been plotted in the space of the operating plasmatron parameters. A phenomenon of a double change of the electric arc flow regime with electric current rise upon constant plasma-forming gas flow rate has been discovered.

Marginal Analysis of the HFCVs Industrialization: Commercialization Scale and the CO<sub>2</sub> Emission Reduction

Focus on the hydrogen fuel cell vehicle industrialization barriers, the paper applies the marginal analysis into the CO2emission reduction of the HFCV. Based on the outputs of the GREET model, the CO2emission reduction amount of the HFCVs, the CO2emissions amount of HFCVs and the scale of the HFCV are calculated separately. Then we build the formulas of the above variables so that the marginal curve of the CO2emission reduction and the commercialization scale of HFCVs are mapped. The conclusion shows the marginal analyze could play a useful role in the CO2emission reduction estimation of the HFCV industrialization.

Does more stringent environmental regulation induce or reduce technology adoption? When the rate of technology adoption is inverted U-shaped

We show that for a broad class of technologies the relationship between policy stringency and the rate of technology adoption is inverted U-shaped. This happens when the marginal abatement cost (MAC) curves of conventional and new technologies intersect, which invariably occurs when emissions are proportional to output and technological progress reduces emissions per output. This outcome does not result from policy failure. On the contrary, in social optimum, the relationship between the slope of the marginal damage curve and the rate of technology adoption is also inverted U-shaped. Under more general conditions, these curves can look even more complicated (e.g., such as inverted W-shaped).

The original composition of the pro‐ostracum of an early Sinemurian belemnite from Belgium deduced from mode of fossilization and ultrastructure

Abstract: The pro‐ostracum of the early Sinemurian belemnite Nannobelus from the Belgian Province of Luxembourg is preserved as a thin, irregularly mineralized (phosphatized and pyritized), finely laminated structure, which is situated dorsally between the calcified rostrum and phragmocone. It has a median field with a criss‐cross pattern of bluntly pointed, curved growth lines and fine longitudinal ridges, as well as two lateral fields characterized by a fine ornament of closely spaced, longitudinal striae, each lateral field showing a narrow anterior belt‐like portion, the width of which equals about one‐third of that of the median field. Their posterior portion is remarkably asymmetrical, because its free margin (which does not about the median field) curves ventrally and the interspace between striae gradually increases here. The striation of the lateral field is formed by the longitudinally exposed narrow portions of succeeding, overlapping sublayers of the pro‐ostracum. Additionally, an internal sublayer with a silicified, honeycomb‐like structure is demonstrated in the pro‐ostracum. Based on microlamination that is comparable to that of the chitinous gladius in extant squids and on the irregular mineralization (unlike the rest of the shell), the pro‐ostracum is considered to have been originally mainly organic, containing an intermediate cartilaginous sublayer with a typical honeycomb‐like structure. The cartilaginous sublayer supposedly provided protection of the pro‐ostracum against fractures which might have resulted from regular contractions together with the muscular mantle during jet‐propulsion. Ultrastructural and chemical data on Nannobelus favour the interpretation of the pro‐ostracum as a novelty of the skeleton in coleoids rather than as a dorsal projection of the phragmocone wall.

Cutting Speed-Feed Based Parametric Model for Macro-Geometrical Deviations in the Dry Turning of UNS A92024 Al-Cu Alloys

This work reports on the results of a study of different macro-geometrical deviation parameters, such as Straightness (SD), Parallelism (PD) and Circularity (CD) as a function of cutting speed (v) and feed (f) of dry turned UNS A92024 (Al-Cu) cylindrical bars. The results obtained have allowed establishing exponentials parametric model for predicting these deviations as a function of those cutting parameters. As a consequence of that, geometrical surfaces SD(f,v), PD(f,v) and CD(f,v) have been developed for this alloy. These surfaces allows determining marginal curves for specific v and f values, respectively, out the parameter ranges employed. So, macro-geometrical deviations can be predicted through this model for v and f values out of those considered in the study for each alloys.

Regulated Prices, Rent Seeking, and Consumer Surplus

Price controls lead to misallocation of goods and encourage rent seeking. The misallocation effect alone ensures that a price control always reduces consumer surplus in an otherwise-competitive market with convex demand if supply is more elastic than demand or with log-convex demand (e.g., constant elasticity) even if supply is inelastic. The same results apply whether rationed goods are allocated by costless lottery or whether costly rent seeking and/or partial decontrol mitigates the inefficiency. Our analysis exploits the observation that in any market, consumer surplus equals the area between the demand curve and the industry marginal revenue curve.

Construction of the marginal abatement cost curve: Retrofitting carbon capture and storage in Australia

Marginal abatement cost curves are a principal tool used for measuring the relative economic impact of emissions abatement mechanisms. Abatement curves can be constructed using either a top-down approach based on aggregated microeconomic models or using a bottom-up approach based on an engineering assessment that analyses different technical potentials for emission reductions. While top-down models offer simplicity and ease of interpretation, they are not as robust as the bottom-up approach, particularly for assessing the implications of new technologies such as carbon capture and storage (CCS). Using a bottom-up approach and incorporating real options analysis, this study redefines the relative abatement costs for retrofitting post-combustion CCS technology to coal-fired generators and then reconstructs the Australian marginal emissions abatement curve. The revised curve provides power generators and other industry sectors with more accurate and stable abatement cost estimates for these technologies relative to alternate abatement options.

Is Product of Two Convex Functions Necessarily Convex? A Case of the MRP Curve

The curvature of the marginal revenue product curve plays an important role in most theoretic microeconomic models since it determines the size of profit contribution to an employer and optimality conditions of solutions. There are many well established introductory and intermediate microeconomic textbooks portray marginal revenue product curves as linear or concave to the origin. In nearly all cases, the MRP cannot be linear, nor can it be concave. In this analysis, most of the well-known production functions generate convex MRP curves.

Onset of Vibrational Convection in a Binary Fluid Saturated Non-Darcy Porous Layer Heated from Above

A linear stability analysis is used to investigate the influence of mechanical vibration on the onset of thermosolutal convection in a horizontal porous layer heated and salted from above. Vibrations are considered with arbitrary amplitude and frequency. The Brinkman extended Darcy model is used to describe the flow and the Oberbeck-Boussinesq approximation is employed. Continued fraction method and Floquet theory are used to determine the convective instability threshold. It is found that the solutal Rayleigh number has the stabilizing effect. The existence of a closed disconnected loop of synchronous mode is predicted in the marginal curve for moderate values of solutal Rayleigh number and vibration amplitude.

Prices vs. Quantities with fiscal cushioning

Enforcement of international environmental quantity regulations (e.g. tradable pollution permits) is often expected to be stricter than that of price regulations (e.g. emission taxes). While both instruments provide opportunities for misrepresenting actual pollution, enforcement of international price-based instruments is additionally hampered by potential fiscal cushioning, i.e. an adjustment of domestic fiscal policies offsetting the tax incentive to reduce emission reductions. The present paper extends the formal debate on Prices vs. Quantities by including the risk of fiscal cushioning. We find the level of the marginal benefit curve and the variance of costs become key elements for instrument choice and can render quantity regulations strictly preferable. Remarkably, in the latter case, the slopes of the marginal curves do not affect optimal instrument choice. Numerical calculations, using data taken from the international climate policy context, support the potential dominance of quantity regulations found in our formal analysis.

Biology as a Source of Non-convexities in Ecological Production Functions

Generating ecological production functions, including harvest yield functions, is a high priority research area. Most yield functions used in economics and ecology rely on convexity properties of species growth functions, but convexity is shown here to depend on whether realistic biology is incorporated. Optimizing behavior by individual organisms is connected with species population dynamics in order to derive growth functions in a general equilibrium ecosystem model. Non convexities are shown to be an inherent property of the growth functions owing to familiar biological processes including predator-prey and competitive relations, predator satiation and prey substitution. The growth functions generate yield functions that are problematic for management, because they exhibit kinked average revenue curves, discontinuous marginal revenue curves, and knife edge optimum effort levels where a small increase above the optimum effort can rapidly deplete the stock. These phenomena can be explained entirely by the underlying biological processes.

Age and growth of Cetengraulis edentulus (Clupeiformes: Engraulidae) in a subtropical bight of Southern Coast Brazil

Age and growth of Cetengraulis edentulus (Cuvier, 1828) in the Saco dos Limoes bight (Southern Brazil) were studied. Sampling was carried out from August 2001 to July 2003. The study of age and growth was based on the interpretation of the periodicity of ring formation in the otoliths sagittae of 491 individuals, temporal variation of otolith edge, relative marginal increments (RMI), age-length key, and von Bertalanffy curve. Cetengraulis edentulus otoliths were adequate for the interpretation of age with 86% of legibility, in which a translucent zone and its adjacent opaque zone were deposited each year. The translucent zone is formed during the cold period and the opaque zone in the warm period. Fish aged 0 (<12 months) - 4.0 year old were found and the population structure reveals the predominance of individuals 1.0 and 2.0 year old. The species has a fast growth, and the growth equation is Lt = 156.70 (1 - e - 1.05 (t - 0.002)). Cetengraulis edentulus attains the sexual maturity with 1.19 year for the females and 1.12 year for the males, which occur in all life stages throughout the year in the study area.

Thermo-electrical instabilities arising in proton exchange membrane of fuel cell

A thermo-electrical model of fuel cell proton exchange membrane is developed and the stability of the system is studied. The marginal curves have been obtained as a function of governed dimensionless parameters. The determined dimensionless parameters allow analyzing different scenarios of non-controlled membrane heating. It has been shown that a positive thermo-electrical feedback can cause instability development and membrane damage in real systems. Recommendations for the improvement of heat management in fuel cells have been proposed using the provided stability study. In particular, it has been demonstrated that decreasing of gas diffusion layer thickness has positive effect and stabilizes the system.

Quantification of economic, environmental and operational benefits due to significant penetration of Microgrids in a typical LV and MV Greek network

AbstractThe effect of the use of a Microgrid Central Controller (MGCC) to achieve co‐ordinated operation of various DG sources, storage devices and controllable loads with regards to the potential economic benefits and the power losses avoided in the local network is presented. Additionally, the effect of connecting numerous typical Microgrids in a typical medium voltage (MV) network regarding power losses and the emissions avoided is studied. The emissions avoidance calculation is based on the marginal emissions curve of the upstream network, quantifying also the calculated losses reduction impact on emissions avoidance. The presented results, based on a variety of realistic market prices time‐series, various levels of renewable energy resource (RES) production and demand from different seasons, show clear benefits in terms of both losses and emissions avoidance. Finally, this paper performs a sensitivity analysis on the potential impact of the DG topology within a Microgrid on losses and emissions avoidance. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Research on International Carbon Emissions Trading and Optimal Exports Scale of China Carbon Emissions

This paper reviews the researches related to international carbon emission right trading. Based on the analysis of marginal abatement curves theory, it has been demonstrated that the fact that different countries or districts have different marginal abatement costs of carbon emission upon respective abatement promise gives rise to international carbon emission right trading. Furthermore, this paper proposes that developing countries should actively participate in the international carbon emission right trading in order to obtain due market benefits. Then, on the basis of the two-phase model, this essay also discusses the optimal exports scale of carbon emission right and its determinant factors, and evaluates the optimal export quantity of carbon emission right for China at the first phase.