Fuel cell system production cost modeling and analysis

In this paper a control-oriented PEM fuel cell system model and a repetitive controller design strategy for PEM fuel cell systems is discussed. A mathematical model of a Polymer Electrolyte Membrane (PEM) Fuel Cell system is presented and then used to design the controller intended to improve system performance. The PEM Fuel cell is tested on an available test station (PEM-FCT) and the data used for the modelling and subsequent controller development study. For model validation a comparison is made between the results from a MATLAB/Simulink model and the test data from the PEM-FCT. The model is then used for repetitive controller design for the fuel cell system. Simulation results show that the repetitive controller tracks the reference signal very closely, with little deviation from the desired value.

In foraging and other productive activities, individuals make choices regarding whether and with whom to cooperate, and in what capacities. The size and composition of cooperative groups can be understood as a self-organized outcome of these choices, which are made under local ecological and social constraints. This article describes a theoretical framework for explaining the size and composition of foraging groups based on three principles: (i) the sexual division of labour; (ii) the intergenerational division of labour; and (iii) economies of scale in production. We test predictions from the theory with data from two field contexts: Tsimane' game hunters of lowland Bolivia, and Jenu Kuruba honey collectors of South India. In each case, we estimate the impacts of group size and individual group members' effort on group success. We characterize differences in the skill requirements of different foraging activities and show that individuals participate more frequently in activities in which they are more efficient. We evaluate returns to scale across different resource types and observe higher returns at larger group sizes in foraging activities (such as hunting large game) that benefit from coordinated and complementary roles. These results inform us that the foraging group size and composition are guided by the motivated choice of individuals on the basis of relative efficiency, benefits of cooperation, opportunity costs and other social considerations.

Liking and Following and the Newsvendor: Operations and Marketing Policies Under Social Influence

Начиная с 1990-х гг. в экономической литературе не ослабевает внимание к теме влияния географического фактора на экономическую динамику и, отсюда, межстрановое и межрегиональное неравенство. Проблемы изолированных удаленных регионов внутри страны актуальны для стран, отличающихся размером территории и разнообразием природных условий, таких как Россия, Канада, Австралия, США. Исследования в области «экономики изоляции и удаленности», выполненные на материале стран мира, привели к созданию концепций и подходов, применимых и к уровню региона, в той мере, в какой регион можно рассматривать как аналог национальной экономики. Статья посвящена анализу теоретических обоснований эффектов удаленности и результатов их эмпирических проверок. Обсуждаемые эффекты иллюстрируются на примере четырех удаленных республик России: Алтая, Тувы, Бурятии и Хакасии.Обзор дискуссии на тему «смерть расстояния» показал, что роль последнего в формировании пространственной структуры экономики не снижается, несмотря на развитие технологий транспортировки и телекоммуникаций. Микроэкономический анализ обнаруживает, что в основе поведения фирмы при выборе места размещения производства лежит взаимодействие транспортных затрат и типа экономии от масштаба. На макроэкономическом уровне эти фундаментальные факторы определяют, как влияют параметры удаленности и размера национальной или региональной экономики на показатели производства и благосостояния. В зависимости от соотношения возможны разнонаправленные эффекты: в общем случае удаленность экономики снижает эффективность производства, уменьшает конкуренцию и затрудняет распространение инноваций, в то время как растущий размер локального рынка позволяет достигать эффектов масштаба в производстве. Поэтому в удаленных регионах возникает специфическая отраслевая структура экономики, для которой характерны ограниченное число отраслей специализации и гипертрофированная доля государственного сектора из-за трудностей доставки общественных благ.Основные рекомендации в области региональной политики для преодоления замкнутости удаленных регионов сводятся к поощрению развития инфраструктуры, поддержки локального спроса и развития человеческого капитала, но их потенциальный положительный эффект ограничен структурными особенностями местных экономик, а долгосрочные последствия повышения транспортной доступности снижают защитный эффект удаленности.

MEDICAL group practices are firms, voluntary contracts between two or more practitioners to jointly provide services, purchase inputs, and distribute income. It is hypothesized that one reason why such organizations are formed is to more efficiently convey information on quality of care to patients, and further, that the increased efficiency of doctor-patient exchange is usually more important than economies of scale in production. A name theory of medical group practice is presented and then tested by comparisons between medicine and dentistry, generalist and specialist practice, and by variations in mobility across patients and providers. Observed variation in the extent and contractual structure of group practice strongly supports the brand name firm hypothesis and is inconsistent with economies of scale explanations.

Urban agglomerations arise at least in part out of the interaction between economies of scale in production and market size effects. This paper develops a simple spatial framework to develop illustrative models of the determinants of urban location, of the number and size of cities, and of the degree of urbanization. A Central theme is the probable existence of multiple equilibria, and the dependence of the range of potential outcomes on a few key parameters.

What is more natural than to expect modem agriculture to be organized in large-scale food factories? Such expectations notwithstanding, a large part of agricultural production - though not all of it - is still done on family farms. Evidently, economies of scale in production, to the extent that they exist, are outweighed by countervailing forces.

and seller concentration is not evidence of countervailing power but merely the result of spurious correlation induced by own industry purchases. When they test this proposition by regressing BCR on SCR, and including dummy variables to account for own industry purchases, the regression coefficient of SCR remains positive and statistically significant at the 0.05 level for 4 and 8 firm CR's. The positive relation becomes insignificant only when the definition of own industry purchases is expanded to include any sales in the same two-digit group. Their justification for a wider definition is that four-digit industries in the same two-digit group use similar technologies and therefore have similar degrees of economies of scale, so that the observed correlation is induced by natural forces rather than by countervailing power. The similarity of economies of scale is asserted, but no supporting evidence is offered. In fact, two-digit groups are rather broad and, for intermediate production, generally contain successive stages of production of a class of finished products. A look at the cases where the top four or eight purchasers are ifl the producing industry's own twodigit group will raise doubts about whether these represent similar, technologies. For BCR4, there were ten cases where the top ranked consuming industry was in the same two-digit group as the producing industry.4 They included the following pairs of four-digit industries: Yarn Mills and Broadwoven Fabrics, Processed Textile Waste and Upholstery, Knit Fabric Mills and Apparel Made from Purchased Materials, Logging Camps and Saw Mills, Pulp Mills and Paper Mills, Paper Mills and Sanitary Paper Products, Primary Aluminum and Aluminum Rolling and Drawing, Secondary NonFerrous Metals and Primary Aluminum, Industrial Controls and Switch Gear. It is doubtful that similar degrees of concentration in these pairs are primarily the result of similar economies of scale in production and not induced by attempts to attain countervailing power.

This paper analyzes a specific model of oligopolistic competition involving product differentiation, marketing activities, and economies of scale in production. It is shown that at a Nash equilibrium each firm must have market share equal to zero or greater than a threshold value. This result has implications for determination of minimum firm size, the effectiveness of a low market share strategy, entry barriers, and the likelihood of concentration in that industry.

The essence of the modern welfare state lies in its institutional commitment to reconcile equity issues with the efficient operation of economic markets in industrial and post‐industrial capitalist societies. As capitalism institutionally relies on the free competition of autonomous individual agents in exchange markets to achieve economic efficiency, but meets with real‐world economies exhibiting an unequal distribution of wealth holdings, economies of scale in production, significant transaction costs, and imperfect information regarding prices and preferences, the unfettered operation of economic forces is likely to result in anything but an egalitarian distribution of economic well‐being in a society. As an institutional antidote, modern welfare states have developed various policy instruments to realign the distributional outcomes of the market with broader social objectives of governments and their constituencies – and hence, the welfare state has rightly come to be seen as institutionally expressing and preserving social solidarity in highly complex societies made up of socially as well as economically highly heterogeneous populations.

We consider a monopolistic firm selling two substitutable products to a stream of sequential arrivals whose purchase decisions can be influenced by earlier purchases. Before demand realizes, the firm faces a newsvendor problem for the two products with economies of scale in production for each. When consumers are responsive to others’ decisions, social influence amplifies demand uncertainty, leading to a lower profit for the firm. We propose three solutions for the firm to better cope with or even benefit from social influence: influencer recruitment and a reduced product assortment either before demand realization (ex ante) or under production postponement (ex post). First, the firm can offer promotional incentives to recruit consumers as influencers. We reveal an operational benefit of influencer marketing that a very small fraction of such influencers is sufficient to diminish sales’ unpredictability. Second, as the potential substitutability between products increases due to social influence, the firm may leverage the increased substitutability and enjoy lower cost in production by reducing product assortment before demand realization. Last, under production postponement, the firm can take advantage of the way that social influence results in demand herding and reduce product varieties by reacting to preorder information. This paper was accepted by Martin Lariviere, operations management.

This paper investigates the impact of economic development on international trade and sources of gains from trade based on a theoretical model that considers consumers’ preference diversity for quality and economies of scale in production. We confirm that both the volume of trade and the share of intra-industry trade increase with increases in the level of economic development in the region. We also find that the intra-industry trade share increases as the technology levels of the two countries become similar. Additionally, we find that both countries can gain from trade and that those gains come from three sources: internal economies of scale, more consumption, and more variety of goods.

Polymer electrolyte membrane fuel cell fault diagnosis and sensor abnormality identification using sensor selection method

Regulation of mobile source emissions in the US has evolved as a complex combination of central government and decentralized authority. The central government required uniform new car emissions standards in the 1970 Clean Air Act, but gave states the power to meet ambient air quality standards however they saw fit, including various regulations on mobile sources. The 1990 Amendments to the Act strengthened the Federal role in some ways, by requiring tighter new car standards and more specific requirements for fuels and for vehicle emissions inspection and maintenance, but at the same time left states with a great deal of latitude to meet ambient standards and took greater recognition of regional variation in environmental problems. We examine the role of various levels of government in attempts to control vehicle emissions in the US, focusing primarily on regulations affecting ambient ozone pollution. Current regulations coming out of the 1990 Amendments are still the subject of much controversy. Several regulations are examined here from the federalist perspective, including the new car standards and the current debate over inspection and maintenance. We discuss the theoretical basis for national uniform regulations, including production scale economies for new cars, pollution spillovers from one jurisdiction to another, and prevention of state non-compliance with ambient air quality goals. For the analysis of economies of scale in production, we model the trade-offs between gains from scale economies in polluted regions and losses from excess controls in cleaner regions, and illustrate the role of interregional transfers or side-payments. These trade-offs and transfers are particularly important as decisions are being made about whether the California cars will be sold only in or whether they will be sold in the Northeast states and elsewhere. We then look at the debate over enhanced I&M. Finally, we draw some tentative conclusions about the future role of the states versus the central government in US ozone policy.

Energy storage and conversion is a very important link between the steps of energy production and energy consumption. Traditional fossil fuels are a natural and unsustainable energy storage medium with limited reserves and notorious pollution problems, therefore demanding a better choice to store and utilize the green and renewable energies in the future. Energy and environmental problems require a clean and efficient way of using the fuels. Fuel cell functions to efficiently convert oxidant and chemical energy accumulated in the fuel directly into DC electric, with the by-products of heat and water. Fuel cells, which are known as effective electrochemical converters, and electricity generation technology has gained attention due to the need for clean energy, the limitation of fossil fuel resources and the capability of a fuel cell to generate electricity without involving any moving mechanical part. The fuel cell technologies that received high interest for commercialization are polymer electrolyte membrane fuel cells (PEMFCs), solid oxide fuel cells (SOFCs), and direct methanol fuel cells (DMFCs). The optimum efficiency for the fuel cell is not bound by the principle of Carnot cycle compared to other traditional power machines that are generally based on thermal cycles such as gas turbines, steam turbines and internal combustion engines. However, the fuel cell applications have been restrained by the high cost needed to commercialize them. Researchers currently focus on the discovery of different materials and manufacturing methods to enhance fuel cell performance and simplify components of fuel cells. Fuel cell systems’ designs are utilized to reduce the costs of the membrane and improve cell efficiency, durability and reliability, allowing them to compete with the traditional combustion engine. In this review, we primarily analyze recent developments in fuel cells technologies and up-to-date modeling for PEMFCs, SOFCs and DMFCs.