This paper reviews our recent work on vibrating sensors for the physical properties of fluids, particularly viscosity and density. Several device designs and the associated properties, specifically with respect to the sensed rheological domain and the onset of non-Newtonian behavior, are discussed.
We present a novel mechanism of particle manipulation in alternating-current (ac)-driven electro-osmotic micropumps, utilizing the tunable ratio of viscous drag, inertial and dielectrophoretic forces. The latter are induced by three-dimensional (3D) stepped electrode arrays in the channel, which are driven by ac voltages enabling so-called 3D-ac-electro-osmotic pumping, as has been proposed recently. Due to size-and density-dependent differences in polarizability, targeted particles in the fluid stream can be slowed down or even pinned above the electrode structures solely by adjusting the operation parameters of the pump. Hence the presented device, fabricated in SU-8/glass technology, enables simultaneous pumping and manipulation of particles in suspension.
We conduct an empirical study on the search and purchasing behavior of buyers on an Austrian price comparison site. On such a market a consumer typically searches for the cheapest price of a given product. Reliability and service of the supplier, however, are other important characteristics of an offer. We find robust evidence of consumer behavior that can be described as a two-stage procedure: shoppers first select a group of candidate offers based on the price only; then, in the actual buying decision consumers tradeoff a lower price with higher reliability of the retailer.JEL Classifications: L81, D83.
Three types of paired preference test were performed on a total of 213 consumers. In each test, consumers were required to choose between two types of chocolate. They performed the traditional preference test which measured relative degrees of liking. Also , they performed a “Choosing” preference tests where they were required to specify which of two chocolates they were more likely to choose when offered both or whether they might choose either or neither. They also performed a “Buying” preference tests where they specified which of two chocolates they were more likely to buy or whether they might buy either or neither. After testing, they were able to take away either one type of chocolate or two types of chocolate. For one group of consumers, this was done while the experimenter was not watching; for the other group, the consumers were being observed. Observing the consumers as they selected chocolates to take away had a biasing effect. Correspondence between the three types of test and what consumers took away with them was low. The results were discussed in term of “test” preferences and “operational” preferences.
PRACTICAL APPLICATIONS
Accurate prediction of acceptance of a product in the marketplace is important. The goal of any test of acceptance is to predict consumer behavior. Therefore, an acceptance test is only valid in terms of how well it predicts the behavior of the consumers in the real world, once they have left the testing situation. It is costly if such tests do not predict this behavior accurately. Accordingly, validation studies should monitor the behavior of the consumers for a requisite amount of time after the test. This has been done for a few studies involving hedonic scales, but there are no published reports for paired preference tests. There is a reluctance to perform such studies because of the time and costs involved. One alternative is to offer consumers the chance to select the products being tested, to take away with them once the test has finished. This might give a clue to “real world” behavior. Since this approach is simple and cost‐effective, it is worth investigating.
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