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Hans Huisman

8 records found

Authored

De terp van Hogebeintum in boorkernen

Book chapter (2019) - Johan Nicolay, Johan Nicolay, Gilles de Langen, Gilles de Langen, Gilles de Langen, Jos Stöver, Gerard Aalbersberg, Gerard Aalbersberg, Gerard Aalbersberg, Gerard Aalbersberg, Gregory Bahlen, Marco Bakker, Marco Bakker, Hans Huisman, Stephan Mantel, D.J.M. Ngan-Tillard, None More Authors

Een dubbele ver(r)assing

Smeltkroesjes uit de Ijzertijd uit Tilburg Sportcomplex Spoordijk

Book chapter (2018) - Hans Huisman, Alicia Bach, Ineke Joosten, Ineke Joosten, D.J.M. Ngan-Tillard, Guido van den Eynde

Het was toeval. De archeologische begeleiding van de uitbreiding van het Tilburgse sportcomplex Spoordijk had slechts enkele sporen en vondsten uit de ijzertijd opgeleverd en was afgesloten. Frans van Nuenen, vrijwilliger in de archeologie, inspecteerde na afloop van de werkzaamh ...

The Valletta Convention: the next 25 years

Abstract (2017) - Hans Huisman, M Groenendijk, D.J.M. Ngan-Tillard, J. Sidell, J. Williams

Signed 25 years ago, the Valletta treaty places a strong emphasis on the protection of archaeological sites. Because of acute threats of archaeological site destruction by construction activities, a major result was a massive increase in rescue and preventative excavations on thr ...

Ghost of loadings past. The case of a Roman vicus under a 19th century embankment in Vechten, The Netherlands

Abstract (2017) - D.J.M. Ngan-Tillard, Hans Huisman

The ratification of the Malta convention has meant that construction works are commonly preceded by research to establish whether damage to archaeological remains will occur. If this is likely, development plans are adapted to enable preservation in-situ or the developer funds a rescue-excavation. A factor playing in favour of in-situ preservation is the overconsolidation of archaeological layers. A soil is said to be overconsolidated when it has been exposed during its history to vertical stresses higher than current ones. As a result, it is only when stresses applied by new constructions exceed the pre-consolidation pressure that soil de-structuration and mechanical damage to archaeology may occur. Many processes can generate overconsolidation at archaeological sites. Site burial followed by erosion, construction of structures, then demolished, soil trampling by heavy animals, drainage of topsoil to keep site occupants’ feet dry, increase of ground water level after site abandonment, but also chemical reactions and ageing can cause over-consolidation. High over-consolidation has been measured in the foundation layers of a high embankment (up to 15 m high) built in the 19th century at Vechten, the Netherlands. The embankment was erected on top of a former Roman vicus established on the natural levee. The Roman level and the 19th century topsoil are rich in fragments of ceramics, bones and metal objects. Over-consolidation pressures are in line with the measured strength and stiffness of the foundation material and the massive soil structures analysed using X-ray micro-computed tomography and micro-morphology. The absence of deflection of the interface between the embankment and its foundation layers indicates that the archaeological layers were already in an over-consolidation state before the construction of the embankment and remained over-consolidated after its construction. In such circumstances, it is only by affecting the groundwater flow and chemistry that the embankment could have degraded underlain archaeology.@en

X-ray micro-CT helps archaeologists to write the biography of ancient ornaments

Abstract (2017) - D.J.M. Ngan-Tillard, Hans Huisman, A. van Gijn

X-ray Micro-Computed Tomography (micro-CT) is an excellent technique to inspect small delicate beads. It reveals their composition and inner structure without damaging them. In particular the geometry of the narrow bead shafts becomes clear on micro-CT scans. Archaeologists can then draw conclusions about the way the beads were made, worn and, in some occasions, re-worked. The origin of the materials selected to make the beads, their production centre and trading routes can even be traced by combining micro-CT scans to other information, such as results of XRF analyses. Signs of post-burial deterioration become obvious. Forgery is easily detected. micro-CT scans also constitute a form of virtual preservation of the ornaments. Once stored in open source repository, they can be further exploited by various stakeholders (musea, archaeologists, the creative industry). The potential of micro-CT is illustrated for two collections of ancient Dutch ornaments: the Neolithic amber beads recovered from several graves and Early Iron Age frothy glass beads from Zutphen. The role of amber beads in the materiality of burial practices in three different periods of the Dutch Neolithic has been investigated by combining microscopy and micro-CT. The scans allowed to evaluate the quality of manufacture and repair of the beads and detect signs of wear, re-shaping and post burial degradation. About 60 glass beads were recovered from an Early Iron Age urn-field near Zutphen (NL). Glass is rare in this period in the Netherlands and has been investigated, first, to determine from what primary glass production centre this glass originated, and by what route it could have reached the Netherlands, and second, to determine the nature and origin of the frothy structure of the beads. With its many glass bubbles, copper fillings and mineral inclusions, the glass of the Zutphen beads does not resemble glass from Mediterranean production sites.@en

Curly malachite on archaeological bronze

A systematic study of the shape and phenomenological approach of its formation mechanism

Journal article (2016) - J. van der Stok-Nienhuis, J. van der Stok-Nienhuis, Luc Robbiola, Roberta Giuliani, Ineke Joosten, Hans Huisman, Bertil van Os, J. Sietsma

Curly malachite (CM) is found as a green cupric carbonate hydroxide corrosion product on archaeological bronze, mostly on artefacts retrieved from graves. In this paper, a morphological characterization approach is proposed, enabling the investigation of the formation process of ...

Solution Space-Based Complexity Analysis of ATC Aircraft Merging Tasks

Conference paper (2009) - P Hermes, Max Mulder, M.M. van Paassen, Hans Huisman, JHL Boering

Contributed

Analysis of methods for determining ship speed during a sea trial

Bachelor thesis (2016) - F.J.L. Buwalda, Cornelis Vuik, C.R. Kleijn, Hans Huisman, Henk Van Den Boom

The aim of this study is to evaluate the performance of two methods for determining the speed of a ship relative to the water during a so called speed trial.
The first method is called the Mean of means method and has been traditionally. The second is called the Iterative method and has been recently developed and is already used for speed trial analysis.
The methods have been evaluated by simulation.
A relationship between ship power and velocity was chosen based on a theoretical analysis, and this relationship is used to generate simulated speed trial data. Using the knowledge of the ’true’ relationship the performance of the methods could then be evaluated after implementation.
The findings are that the Iterative method needs a minimum of 8 measurements obtained by sailing back and forth 4 times in order to find the true relationship with acceptable
accuracy.
The Mean of means method needs a minimum of 12 measurements,
or 6 double runs.
The conclusion is that the Iterative method is more time efficient
for speed trial analysis.
In a test case assuming realistic measurement noise, 99:3% of found speeds had an error smaller than the simulated error margin of 0.1 knots, out of a sample size of 1000.
When comparing the Iterative to the Mean of means method under the same conditions, the Mean of means method made smaller errors for all observed cases.
From the results of this study has been concluded that the Iterative method is usable method for determining ship speed during a sea trial that has both advantages and disadvantages over the traditional Mean of means method.
Advantages are that the Iterative method requires less measurements than the Mean of means method, and it remains accurate even if measurements have a large or varying spacing in time.
A disadvantage is that it is more sensitive to measurement noise than the Mean of means method, making it prone to making larger errors.
A small adjustment to the current function the method assumes and uses for calculating current effects has been proposed.
The adjustment was to normalize the component of the current function that scales linearly with time.
This has been found to have a positive impact on the performance of the method.