基爾大學

Freeze–thaw deformation in frost-susceptible soils couples heat transfer, phase change, water redistribution and irreversible thaw deformation. This study develops an axisymmetric Voronoi–Delaunay lattice framework with a finite-element-analysis-program (FEAP)-compatible residual–tangent organization, embedded displacement-jump histories and a bounded temperature-dependent creep law. Delaunay edges carry normal–shear interactions, while a circumcentric dual supplies transport faces and storage volumes. The global benchmark implementation combines apparent-heat-capacity heat transfer, a reduced total-water redistribution equation and fixed-reference small-strain lattice mechanics; it is not a complete Darcy-flow, effective-stress or discrete ice-lens formulation. Verification against radial conduction, Stefan-front propagation and confined compression produced errors of 1.45%, 3.53% and 5.88%, respectively. First-cycle heave and thaw-settlement endpoints from one closed Kieler Förde test and six independent open-system tests were used for case-level calibration. The calibrated model reproduced those endpoints with a median absolute percentage error of 0.36%. The subsequent Kieler Förde cycle trend was assessed without further endpoint calibration, and the FEAP jump–creep enrichment retained a median endpoint error of 3.03% without re-optimisation. Predicted temperature, ice fraction, total water, pressure proxy and displacement fields are reported as model outputs because co-registered water-content profiles, pore pressures and freezing-front positions were not available for every case. Four CPU workers produced a measured 3.25-fold batch speedup; an optional GPU sparse-solver route is supplied with deterministic CPU fallback. The framework is therefore intended for rapid laboratory-scale displacement assessment, while finite-strain kinematics and fully coupled ice-lens poromechanics remain future developments.

We estimate productivity spillovers from Japanese cotton-spinning firms in China (known as Zaikabo,"(sic)(sic)(sic)") to local Chinese cotton-spinning mills based on plant-level data for 1925 to 1938. In order to capture the important role of distance in facilitating such spillovers we geo-localised the plants. Our results provide clear evidence for positive spillovers from Zaikabo to local Chinese mills, which go hand-in-hand with an upgrade in production technology towards greater use of capital. Spillovers are very localised, being strongest within a radius of up to 10 km around the Zaikabo and particularly strong for mills in Shanghai. Exploiting information on the workforce composition of the Japanese affiliates, we find suggestive evidence of a skilled-labour channel: spillovers tend to be larger from Zaikabo employing higher shares of skilled labour. We also find some evidence in line with the idea that these gains are larger for Chinese mills with higher initial productivity, consistent with a role for absorptive capacity. Our paper is the first to document FDI productivity spillovers in a historical context and to characterise the channels through which they operate.

Research on the nexus between development and migration has mainly focused on cross-border flows. How income changes affect migration within developing countries is much less well researched even though addressing this topic might provide essential information about the process of structural transformation needed for economic development. In this paper, we provide new evidence on the link between income growth and internal migration for Malawi, a developing country where migration is predominantly internal. Employing a gravity approach and performing an instrumental variable regression based on a shift-share instrument, we robustly find that, on average, rising incomes – proxied by changes in nightlight intensity – are associated with higher emigration rates. This effect is mainly driven by people emigrating from comparably richer urban areas. In the poorer rural districts, by contrast, migration tends to fall with increasing economic activity, which is in accordance with the notion that poverty may force people to leave their home in response to negative shocks. Our results also suggest a specific sorting pattern: While in urban areas rising incomes mainly facilitate the emigration of lower-skilled people to non-urban destinations, in rural areas it is higher-skilled people who most likely leave their home in response to falling incomes, often moving to urban destinations. This empirical finding is consistent with a standard theoretical model where populations sort themselves geographically on the basis of skills, for which there is relatively higher demand and a higher return in urban areas.

This paper investigates how the specific design of an agglomeration bonus affects farmers' willingness to participate in a stylised peatland restoration scheme. The analysis is based on a discrete choice experiment with 110 farmers from peatland regions in northwest Germany. The results suggest that, relative to the scheme's land-use restrictions, the agglomeration bonus plays a minor role in the decision to participate in the scheme. The bonus had no statistically significant effect in the mixed logit estimations and was mostly ignored in the decision-making process. Only when preferences are adjusted for attribute non-attendance does the bonus enhance willingness to participate and the scheme's cost-effectiveness. Respondents who did not ignore the attributes of bonus design preferred a lump sum payment at the start of the scheme to an annual disbursement of the bonus, and an area-based bonus to a neighbourhood bonus. More generally, the results suggest that only mediocre levels of commitment on the part of farmers can be achieved through a voluntary approach. More ambitious peatland restoration, which may be necessary to achieve the reduction targets in the LULUCF sector, will need to combine incentive systems with regulatory or planning instruments.

As unconventional hydrocarbon exploration increasingly targets deeply buried, highly mature source rocks, there is a growing need to accurately characterize organic matter exposed to extreme thermal conditions. A key analytical challenge in such systems is the reliable determination of total organic carbon (TOC), thermal maturity (Tmax), and hydrocarbon generation potential (S2 and Hydrogen Index, HI) using standard Rock-Eval pyrolysis. In overmature samples, the conventional upper pyrolysis temperature of 650 degrees C is insufficient to fully evolve the S2 peak, resulting in underestimated S2 and TOC values and unreliable Tmax determinations. To overcome this limitation, this study introduces a modified extended temperature programmed pyrolysis protocol that extending the final temperature to 850 degrees C on a series of synthetically matured shale samples produced by confined-pressure hydrous pyrolysis across a range of thermal maturities. The results show that this approach enables complete S2 evolution where conventional Rock-Eval analysis fails to resolve the hydrocarbon generation signal. The resulting S2 pyrograms exhibit a bimodal distribution, with the first peak corresponding to residual kerogen and the second to pyrobitumen formation. Systematic evolution of the second peak yields robust Tmax values show a strong linear relationship with thermal maturity (Tmax = 95.17 EASY%Ro + 345.96), indicating that pyrobitumen serves as a reliable proxy for advanced thermal maturity. These results show that standard Rock-Eval protocols can significantly underestimate TOC and misrepresent maturity in overmature source rocks, whereas high-temperature programmed pyrolysis extends the applicability of pyrolysis-based geochemical parameters into the overmature domain. By enabling more accurate characterization of highly evolved organic matter, this method provides a practical and improved geochemical foundation for basin modeling and thermal simulation studies, addressing a critical gap in the evaluation of overmature petroleum systems.