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- ItemAmmonia and greenhouse gas emissions from slurry storage : A review(Amsterdam [u.a.] : Elsevier, 2020) Kupper, Thomas; Häni, Christoph; Neftel, Albrecht; Kincaid, Chris; Bühler, Marcel; Amon, Barbara; VanderZaag, AndrewStorage of slurry is an important emission source for ammonia (NH3), nitrous oxide (N2O), methane (CH4), carbon dioxide (CO2) and hydrogen sulfide (H2S) from livestock production. Therefore, this study collected published emission data from stored cattle and pig slurry to determine baseline emission values and emission changes due to slurry treatment and coverage of stores. Emission data were collected from 120 papers yielding 711 records of measurements conducted at farm-, pilot- and laboratory-scale. The emission data reported in a multitude of units were standardized and compiled in a database. Descriptive statistics of the data from untreated slurry stored uncovered revealed a large variability in emissions for all gases. To determine baseline emissions, average values based on a weighting of the emission data according to the season and the duration of the emission measurements were constructed using the data from farm-scale and pilot-scale studies. Baseline emissions for cattle and pig slurry stored uncovered were calculated. When possible, it was further distinguished between storage in tanks without slurry treatment and storage in lagoons which implies solid-liquid separation and biological treatment. The baseline emissions on an area or volume basis are: for NH3: 0.12 g m−2 h-1 and 0.15 g m−2 h-1 for cattle and pig slurry stored in lagoons, and 0.08 g m−2 h-1 and 0.24 g m−2 h-1 for cattle and pig slurry stored in tanks; for N2O: 0.0003 g m−2 h-1 for cattle slurry stored in lagoons, and 0.002 g m−2 h-1 for both slurry types stored in tanks; for CH4: 0.95 g m-3 h-1 and 3.5 g m-3 h-1 for cattle and pig slurry stored in lagoons, and 0.58 g m-3 h-1 and 0.68 g m-3 h-1 for cattle and pig slurry stored in tanks; for CO2: 6.6 g m−2 h-1 and 0.3 g m−2 h-1 for cattle and pig slurry stored in lagoons, and 8.0 g m−2 h-1 for both slurry types stored in tanks; for H2S: 0.04 g m−2 h-1 and 0.01 g m−2 h-1 for cattle and pig slurry stored in lagoons. Related to total ammoniacal nitrogen (TAN), baseline emissions for tanks are 16% and 15% of TAN for cattle and pig slurry, respectively. Emissions of N2O and CH4 relative to nitrogen (N) and volatile solids (VS) are 0.13% of N and 0.10% of N and 2.9% of VS and 4.7% of VS for cattle and pig slurry, respectively. Total greenhouse gas emissions from slurry stores are dominated by CH4. The records on slurry treatment using acidification show a reduction of NH3 and CH4 emissions during storage while an increase occurs for N2O and a minor change for CO2 as compared to untreated slurry. Solid-liquid separation causes higher losses for NH3 and a reduction in CH4, N2O and CO2 emissions. Anaerobically digested slurry shows higher emissions during storage for NH3 while losses tend to be lower for CH4 and little changes occur for N2O and CO2 compared to untreated slurry. All cover types are found to be efficient for emission mitigation of NH3 from stores. The N2O emissions increase in many cases due to coverage. Lower CH4 emissions occur for impermeable covers as compared to uncovered slurry storage while for permeable covers the effect is unclear or emissions tend to increase. Limited and inconsistent data regarding emission changes with covering stores are available for CO2 and H2S. The compiled data provide a basis for improving emission inventories and highlight the need for further research to reduce uncertainty and fill data gaps regarding emissions from slurry storage.
- ItemGlobal bilateral migration projections accounting for diasporas, transit and return flows, and poverty constraints(Rostock : Max Planck Inst. for Demographic Research, 2021) Rikani, Albano; Schewe, JacobBACKGROUND Anticipating changes in international migration patterns is useful for demographic studies and for designing policies that support the well-being of those involved. Existing forecasting methods do not account for a number of stylized facts that emerge from large-scale migration observations and theories: existing migrant communities - diasporas - act to lower migration costs and thereby provide a mechanism of self-amplification; return migration and transit migration are important components of global migration flows; and poverty constrains emigration. OBJECTIVE Here we present hindcasts and future projections of international migration that explicitly account for these nonlinear features. METHODS We develop a dynamic model that simulates migration flows by origin, destination, and place of birth. We calibrate the model using recently constructed global datasets of bilateral migration. RESULTS We show that the model reproduces past patterns and trends well based only on initial migrant stocks and changes in national incomes. We then project migration flows under future scenarios of global socioeconomic development. CONCLUSIONS Different assumptions about income levels and between-country inequality lead to markedly different migration trajectories, with migration flows either converging towards net zero if incomes in presently poor countries catch up with the rest of the world; or remaining high or even rising throughout the 21st century if economic development is slower and more unequal. Importantly, diasporas induce significant inertia and sizable return migration flows. CONTRIBUTION Our simulation model provides a versatile tool for assessing the impacts of different socioeconomic futures on international migration, accounting for important nonlinearities in migration drivers and flows.
- ItemHow activated carbon improves the performance of non-thermal plasma removing methyl ethyl ketone from a gas stream([Amsterdam] : Elsevier B.V., 2021) Schmidt, Michael; Kettlitz, Manfred; Kolb, Juergen F.The combination of non-thermal plasma (NTP), operated at room temperature and at atmospheric pressure in air and in combination with activated carbon filters offers a more efficient removal of VOCs from gas streams than each individual method alone. Efficiencies, synergies and mechanisms of this combination were investigated by means of comprehensive quantitative Fourier transform infrared spectroscopy analysis. Therefore, dry and wet synthetic air containing about 90 ppm of methyl ethyl ketone (MEK) were treated with non-thermal plasma (NTP) and an intentionally undersized activated carbon (AC) filter, separately and in combination. As a result, removal of about 50 % was achieved for NTP or AC alone but a removal close to 95 % was found for the combination. Ozone, generated by the NTP, was reduced by 55 % with the AC-filter. For the operation of the NTP with humid air, a decomposition of the pollutant on AC was observed even after the plasma was switched off.
- ItemOn the algorithmic solution of optimization problems subject to probabilistic/robust (probust) constraints(Berlin ; Heidelberg : Springer, 2021) Berthold, Holger; Heitsch, Holger; Henrion, René; Schwientek, JanWe present an adaptive grid refinement algorithm to solve probabilistic optimization problems with infinitely many random constraints. Using a bilevel approach, we iteratively aggregate inequalities that provide most information not in a geometric but in a probabilistic sense. This conceptual idea, for which a convergence proof is provided, is then adapted to an implementable algorithm. The efficiency of our approach when compared to naive methods based on uniform grid refinement is illustrated for a numerical test example as well as for a water reservoir problem with joint probabilistic filling level constraints.
- ItemWhen redistribution makes personalized pricing of externalities useless(Oxford : Wiley-Blackwell, 2021) Fleurbaey, Marc; Kornek, UlrikeWe consider a standard optimal taxation framework in which consumers' preferences are separable in consumption and labor and identical over consumption, but are affected by consumption externalities. For every nonlinear, income-dependent pricing of goods there is a linear pricing scheme, combined with an adjusted income tax schedule, that leaves all consumers equally well-off and weakly increases the government's budget. The result depends on whether a linear pricing scheme exists that keeps the aggregate amount of consumption at its initial level observed under nonlinear pricing. We provide sufficient conditions for the assumption to hold. If adjusting the income tax rate is not available, personalized prices for an externality can enhance social welfare if they are redistributive, that is, favor consumers with a larger marginal social value of income.
- ItemInformation exchange in laboratory markets: competition, transfer costs, and the emergence of reputation(Dordrecht [u.a.] : Springer Science + Business Media B.V., 2020) Hoffmann, Roman; Kittel, Bernhard; Larsen, MattiasPublic reputation mechanisms are an effective means to limit opportunistic behavior in markets suffering from moral hazard problems. While previous research was mostly concerned with the influence of exogenous feedback mechanisms, this study considers the endogenous emergence of reputation through deliberate information sharing among actors and the role of barriers in hindering information exchange. Using a repeated investment game, we analyze the effects of competition and transfer costs on players’ willingness to share information with each other. While transfer costs are a direct cost of the information exchange, competition costs represent an indirect cost that arises when the transfer of valuable information to competitors comes at the loss of a competitive advantage. We show that barriers to information exchange not only affect the behavior of the senders of information, but also affect the ones about whom the information is shared. While the possibility of sharing information about others significantly improves trust and market efficiency, both competition and direct transfer costs diminish the positive effect by substantially reducing the level of information exchange. Players about whom the information is shared anticipate and react to the changes in the costs by behaving more or less cooperatively. For reputation building, an environment is needed that fosters the sharing of information. Reciprocity is key to understanding information exchange. Even when it is costly, information sharing is used as a way to sanction others. © 2020, The Author(s).
- ItemOptimal Control Problems with Sparsity for Tumor Growth Models Involving Variational Inequalities(Dordrecht [u.a.] : Springer Science + Business Media, 2022) Colli, Pierluigi; Signori, Andrea; Sprekels, JürgenThis paper treats a distributed optimal control problem for a tumor growth model of Cahn–Hilliard type. The evolution of the tumor fraction is governed by a variational inequality corresponding to a double obstacle nonlinearity occurring in the associated potential. In addition, the control and state variables are nonlinearly coupled and, furthermore, the cost functional contains a nondifferentiable term like the L1-norm in order to include sparsity effects which is of utmost relevance, especially time sparsity, in the context of cancer therapies as applying a control to the system reflects in exposing the patient to an intensive medical treatment. To cope with the difficulties originating from the variational inequality in the state system, we employ the so-called deep quench approximation in which the convex part of the double obstacle potential is approximated by logarithmic functions. For such functions, first-order necessary conditions of optimality can be established by invoking recent results. We use these results to derive corresponding optimality conditions also for the double obstacle case, by deducing a variational inequality in terms of the associated adjoint state variables. The resulting variational inequality can be exploited to also obtain sparsity results for the optimal controls.
- ItemLeveraging Artificial Intelligence in Marketing for Social Good—An Ethical Perspective(Dordrecht : Springer, 2021) Hermann, ErikArtificial intelligence (AI) is (re)shaping strategy, activities, interactions, and relationships in business and specifically in marketing. The drawback of the substantial opportunities AI systems and applications (will) provide in marketing are ethical controversies. Building on the literature on AI ethics, the authors systematically scrutinize the ethical challenges of deploying AI in marketing from a multi-stakeholder perspective. By revealing interdependencies and tensions between ethical principles, the authors shed light on the applicability of a purely principled, deontological approach to AI ethics in marketing. To reconcile some of these tensions and account for the AI-for-social-good perspective, the authors make suggestions of how AI in marketing can be leveraged to promote societal and environmental well-being.
- ItemFiscal Consolidation Programs and Income Inequality(Malden, Mass. [u.a.] : Wiley-Blackwell, 2020) Brinca, Pedro; Ferreira, Miguel H.; Franco, Francesco; Holter, Hans A.; Malafry, LaurenceWe document a strong empirical relationship between higher income inequality and stronger recessive impacts of fiscal consolidation episodes across time and space. To explain this finding, we develop a life-cycle economy with uninsurable income risk. We calibrate our model to match key characteristics of several European economies, including inequality and fiscal structures, and study the effects of fiscal consolidation programs. In our model, higher income risk induces precautionary savings behavior, which decreases the proportion of credit-constrained agents in the economy. These agents have less elastic labor supply responses to fiscal consolidations, which explain the correlation with inequality in the data.
- ItemOptimal carbon taxation and horizontal equity: A welfare-theoretic approach with application to German household data(Amsterdam : Elsevier, 2022) Hänsel, Martin C.; Franks, Max; Kalkuhl, Matthias; Edenhofer, OttmarWe develop a model of optimal taxation and redistribution under an ambitious climate target. We take into account vertical income differences, but also explicitly capture horizontal equity concerns by considering heterogeneous energy efficiencies. By deriving first- and second-best rules for policy instruments including carbon and labor taxes, transfers and energy subsidies, we investigate analytically how vertical and horizontal inequality is considered in the welfare maximizing tax structure. We calibrate the model to German household data and a 30 percent emission reduction goal and show that redistribution of carbon tax revenues via household-specific transfers is the first-best policy. Under plausible assumptions on inequality aversion, transfers to energy-intensive households should be about five times higher than transfers to energy-efficient households. Equal per-capita transfers do not require to observe households’ efficiency type, but increase equity-weighted mitigation costs by around 5 percent compared to the first-best. Mitigation costs increase by less, if the government can implement a uniform clean energy subsidy or household-specific tax-subsidy schemes on energy consumption and labor income that target heterogeneous energy efficiencies. Horizontal equity concerns may therefore constitute a new second-best rationale for clean energy policies or differentiated energy taxes.