Prehistoric chamber tombs or geological pitfall? A multimethod case study from Ancient Aigeira with a focus on seismic full‐waveform inversion

We show an extensive multimethod geophysical study of focusing on someenigmatic subsurface structures found at Ancient Aigeira (N Peloponnes, Greece) thatcould be interpreted either as prehistoric chamber tombs or complex weatheringpatterns of the local marl–conglomerate rock sequences. It turns out that the non-seismic methods do not allow to distinguish between an archaeological and a geologi-cal origin of the observed patterns with certainty. In contrast, we demonstrate howshear-wave seismics and full-waveform inversion (FWI) can be used in archaeologicalprospection for distinguishing between these alternative essentially differentinterpretational models that are not distinguishable through nonseismic prospectiondata. The example site Aigeira is strategically well located on a hill on the NorthernPeloponnese overlooking the Corinthian Gulf and has been inhabited with occupa-tional gaps since Middle Neolithic times until the 12th to early 14th centuryCE.Magnetics, ground-penetrating radar (GPR) and electrical resistivity tomography(ERT) reveal a honeycomb-shaped anomaly pattern that could have been interpretedas a system of prehistoric chamber tombs. The time-domain SH-FWI strategy basedon a sequential inversion of low-pass and band-pass filtered data results insubsurface models for shear-wave velocity and density that accurately fits the com-plicated seismic data set.With the help of the seismic survey, we can reject the interpretationhypothesis of a prehistoric cemetery with chamber tombs and confirm that theenigmatic geophysical patterns represent a geological weathering structure thatcould be addressed as a reincised fan delta draped by reddish palaeosols

Optimization of pneumatic vacuum generators – heading for energy-efficient handling processes

In current production systems, automation and handling of workpieces is often solved by use of vacuum technology. Most production systems use vacuum ejectors which generate vacuum from compressed air by means of the Venturi effect. However, producing vacuum with compressed air is significantly less efficient than using other principles. To minimize the energy costs of pneumatic vacuum generation or to make full use of the energy available, it is important that the inner contour of the nozzle is shaped precisely to suit the specific application - also the system\'s flow conduction needs to be optimal and the flow losses have to be minimized. This paper presents a method for optimally designing pneumatic vacuum generators and producing them economically even at very low lot sizes in order to keep the operation costs low and address other concerns (such as noise emissions) as well

Considerations on aegean bronze age fortifications

The current paper summarizes the development of Bronze Age Aegean fortifications with a special focus on the Aegean Early and Middle Bronze Age. In order to get a better understanding of Aegean fortifications for each period, their numbers are set into relation with the number of known sites and other features. The impressive multi-phased fortifications of sites such as Troy or Kolonna on the island of Aegina will be used as case studies to explain the development of Early to Middle Bronze Age sites in the central Aegean. The final part of the paper gives a preview on the development of Late Bronze Age (Mycenaean palatial and postpalatial) fortifications

Optimization of pneumatic vacuum generators – heading for energy-efficient handling processes

In current production systems, automation and handling of workpieces is often solved by use of vacuum technology. Most production systems use vacuum ejectors which generate vacuum from compressed air by means of the Venturi effect. However, producing vacuum with compressed air is significantly less efficient than using other principles. To minimize the energy costs of pneumatic vacuum generation or to make full use of the energy available, it is important that the inner contour of the nozzle is shaped precisely to suit the specific application - also the system\'s flow conduction needs to be optimal and the flow losses have to be minimized. This paper presents a method for optimally designing pneumatic vacuum generators and producing them economically even at very low lot sizes in order to keep the operation costs low and address other concerns (such as noise emissions) as well

Prehistoric chamber tombs or geological pitfall? A multimethod case study from Ancient Aigeira with a focus on seismic full‐waveform inversion

We show an extensive multimethod geophysical study of focusing on some enigmatic subsurface structures found at Ancient Aigeira (N Peloponnes, Greece) that could be interpreted either as prehistoric chamber tombs or complex weathering patterns of the local marl–conglomerate rock sequences. It turns out that the nonseismic methods do not allow to distinguish between an archaeological and a geological origin of the observed patterns with certainty. In contrast, we demonstrate how shear‐wave seismics and full‐waveform inversion (FWI) can be used in archaeological prospection for distinguishing between these alternative essentially different interpretational models that are not distinguishable through nonseismic prospection data. The example site Aigeira is strategically well located on a hill on the Northern Peloponnese overlooking the Corinthian Gulf and has been inhabited with occupational gaps since Middle Neolithic times until the 12th to early 14th century ce. Magnetics, ground‐penetrating radar (GPR) and electrical resistivity tomography (ERT) reveal a honeycomb‐shaped anomaly pattern that could have been interpreted as a system of prehistoric chamber tombs. The time‐domain SH‐FWI strategy based on a sequential inversion of low‐pass and band‐pass filtered data results in subsurface models for shear‐wave velocity and density that accurately fits the complicated seismic data set. A highly heterogeneous subsurface is revealed that is characterized by linear cracks on a decimetre scale. The seismic FWI results are compared in detail with GPR, ERT and among each other. It turns out that the FWI result is consistent with each of these other geophysical methods but provides a more comprehensive subsurface characterization that it is supported by corings in addition. With the help of the seismic survey, we can reject the interpretation hypothesis of a prehistoric cemetery with chamber tombs and confirm that the enigmatic geophysical patterns represent a geological weathering structure that could be addressed as a reincised fan delta draped by reddish palaeosols.Land Schleswig‐Holstein http://dx.doi.org/10.13039/100018877Institute of Aegean Prehistory (INSTAP) http://dx.doi.org/10.13039/100001182Ephorate of Antiquities of AchaiaHellenic Ministry of Culture and SportAustrian Archaeological Institute and the Austrian Academy of Science

Optimization of pneumatic vacuum generators – heading for energy-efficient handling processes

In current production systems, automation and handling of workpieces is often solved by use of vacuum technology. Most production systems use vacuum ejectors which generate vacuum from compressed air by means of the Venturi effect. However, producing vacuum with compressed air is significantly less efficient than using other principles. To minimize the energy costs of pneumatic vacuum generation or to make full use of the energy available, it is important that the inner contour of the nozzle is shaped precisely to suit the specific application - also the system\'s flow conduction needs to be optimal and the flow losses have to be minimized. This paper presents a method for optimally designing pneumatic vacuum generators and producing them economically even at very low lot sizes in order to keep the operation costs low and address other concerns (such as noise emissions) as well

Geological Challenges of Archaeological Prospecting:The Northern Peloponnese as a type location of populated syn-rift settings

The Northern Peloponnese is not only home of a series of ancient poleis that are being studied by archaeologists, but it is also located on the southern shoulder of the most active extensional crustal structure in the world; the Corinthian rift. This rift has shaped the Northern Peloponnese as we now see it today since the Pliocene. Normal faulting, the tectonic uplift of syn-rift sediments and sea level changes, has shaped a landscape of steps rising from the coast to the ridges in the hinterland that provides challenging conditions to a geophysical survey. Where we can find coarse grained slope and delta deposits of conglomerate on top of banks of marl on ridges and slopes, the lower marine terraces and the coastal plain as well as valleys show the protective caprock eroded and the marl covered by young alluvial deposits. These materials show only a small contrast in their magnetic properties, which reduces the importance of magnetic mapping for the archaeological prospection in this region. The human utilization of the coastal plain and the urban areas pose additional challenges. These challenges have been overcome through various approaches that are shown in exemplary case studies from Aigeira and Sikyon. Whereas a combination of magnetic mapping and ground-penetrating radar (GPR) works very well on the ridges and along the slopes where we find coarser sediments in addition to the magnetic mapping, it is not suitable in the coastal plain due to the attenuating properties of the alluvial sediment. Here, electrical resistivity tomography (ERT) proved to be very successful in mapping entire parts of a settlement in great detail. Seismic soundings were also sucessfully applied in determining the bedrock depth, the detection of walls and in the question of locating the harbor basin. In the presented six exemplary case studies, the following findings were made: (1) A fortification wall and building foundations at a depth of 0.4–1.2 m on a plateau northwest of the acropolis of Aigeira was found by 400 MHz GPR. (2) A honeycomb-shaped pattern of magnetic anomalies that suggested cavities could be identified as a weathering pattern of conglomerate rocks. (3) A rock basement 2.3 m deep and remains of an enclosing wall of the Aigeira theater area were found by shear wave refraction measurements. (4) Extensive ERT surveys detected several building remains in Sikyon like a potential building and grave monuments as well as several small houses. (5) A silted-up depression in the sediments of the coastal plane located through Love wave measurements, could be taken as evidence for either a silted harbor or a navigable riverbed