Wave Propagation in the Ground and Isolation Measures

The first part of this report deals with wave propagation in the ground. Special attention is given to the radiation of waves from a source and on the effect of layering or continuous variation of the shear modulus in the soil on travelling waves. In the second part, vibration isolation measures are described, such as open or infilled trenches and rows of bore holes or piles. The results of different theoretical and experimental investigations are compared. Finally, recently developed isolation measures are presented

Searching for the Rail Bonus

The inherent superiority of rail-based public transport options over bus-based alternatives, all other things being equal, has been stipulated in the literature and in the public policy discussion for some time. The exact strength of any such rail bonus is important to a public transport operator which has to consider the replacement of rail-based services by bus services. The public transport operator of the city of Dresden (DVB), while generally upgrading its services, has to consider this option, in particular where the continuing tram operation would require a costly rehabilitation of the tracks. The measurement of any such systematic preference for rail-based modes is difficult, as is requires either a before-and-after study of such a switch, controlled for the other relevant service attributes, e.g. frequency, speed, reliability, price, route, etc., or a study of a network, in which rail- and road-based modes offer comparable types of services, with bus services inparticular not restricted to feeder services to rail/tram lines. Both are rare for obvious reasons. A recent service change of the DVB offered the opportunity to look at the issue in detail. A series of surveys were undertaken for this purpose before and after: A one-day travel diary (including a household questionnaire)  A survey of the image of the services A between-mode stated preference exercise focusing on the choice between public transport and private motorised transport where public transport was provided by either bus or tram (7 choice situations) A within-mode stated preference exercise looking at the trade-offs between public transport modes, in particular levels of comfort, travel times and transfers (7 choice situations). The paper reports detailed results from this study addressing the differences in preferences between the waves (effects of familiarity with an alternative) from both separate and joint stated preference and stated preference/revealed preference models. The modelling so far indicates a consistent, but weak preference for the rail option through a higher value-of-time for rail usage, higher valuation of new rail vehicles in comparison to new busses, although they are partially balanced by a higher transfer penalty. &nbsp

Stochastic optimization of a cold atom experiment using a genetic algorithm

We employ an evolutionary algorithm to automatically optimize different stages of a cold atom experiment without human intervention. This approach closes the loop between computer based experimental control systems and automatic real time analysis and can be applied to a wide range of experimental situations. The genetic algorithm quickly and reliably converges to the most performing parameter set independent of the starting population. Especially in many-dimensional or connected parameter spaces the automatic optimization outperforms a manual search.Comment: 4 pages, 3 figure

Diffusion and upscaling of municipal climate mitigation and adaptation strategies in Germany

Drawing on data for the 104 largest German cities, and deeper analysis of six mid-sized cities (including forerunners, followers and latecomers in climate mitigation and adaptation), we find that the spread of local mitigation and adaptation strategies across Germany can be explained by a combination of horizontal diffusion and vertical upscaling. Specifically, while the spread of climate mitigation initiatives in the 1990s was triggered primarily by transnational municipal networks (horizontal diffusion), the development and revision of climate mitigation strategies and the emergence of climate adaptation strategies during the last decade have been driven mainly by national and subnational funding programmes (vertical upscaling). Notably, forerunner cities are less dependent on external funding than followers and latecomers, because they have more internal capacity to act. By arguing that upscaling of local climate policies from forerunners to followers and latecomers depends on interventions by national and subnational authorities, we stress that the majority of German municipalities require external support in order to develop and implement effective climate strategies

Structure, agency and local climate governance: how do individual actors exploit local contexts to shape policymaking in smaller cities and towns?

A growing literature has emphasised how structural factors shape levels of ambition in local climate policy. Specifically, cities that have larger, wealthier, highly-educated and younger populations, are supported by local universities and research institutes and in which civil society organisations and green parties are strong and active, are more likely to be ‘leaders’ in climate mitigation and adaptation (Haupt et al 2022). Conversely, smaller towns, with less wealthy and older populations, which are more reliant on heavy industry and with weaker civil society organisations and green parties, are more likely to be ‘laggards’ (Otto et al 2021; Salvia et al 2021). Such studies are informative from an academic perspective (because they identify the key factors that contribute towards more ambitious policymaking), and instructive for policymakers (who can pinpoint where additional support and funding schemes may be necessary to ensure that all cities keep pace with the leaders). However, they neglect to take account of agency and the likelihood that individuals in some municipalities can pursue ambitious climate policy despite operating in unfavourable local conditions. At the same time, cities that we might expect to become leaders due to their socioeconomic and political conditions may instead be slower to adopt ambitious policies due to the actions of key individuals in the municipality

Experimental and analytic studies of the triggered lightning environment of the F106B

The triggered lightning environment of the F106B aircraft is investigated. Scale modeling of the F106B with a metallized model was done to measure electric field enhancement factors on the aircraft and on canonically shaped conducting objects. These are then compared to numerically determined quantities. Detailed numerical modeling is done of the development of the triggered lightning channel. This is done using nonlinear air chemistry models to model a variety of physical phenomena which occur in a triggered lightning event. The effect of a triggered lightning strike on internal wires in the F106B is investigated using finite difference models and transmission line models to calculate the electromagnetic coupling of lightning currents through seams and joints of the aircraft to internal cables. Time domain waveforms are computed and compared to measured waveforms. The effect of thunderstorm particles on the initial triggering of a lightning strike is investigated. The electric field levels needed to cause air breakdown in the presence and absence of thunderstorm particles are calculated. This is done as a function of the size, shape, and density of the particles