Decomposition driven interface evolution for layers of binary mixtures: {II}. Influence of convective transport on linear stability

We study the linear stability with respect to lateral perturbations of free surface films of polymer mixtures on solid substrates. The study focuses on the stability properties of the stratified and homogeneous steady film states studied in Part I [U. Thiele, S. Madruga and L. Frastia, Phys. Fluids 19, 122106 (2007)]. To this aim, the linearized bulk equations and boundary equations are solved using continuation techniques for several different cases of energetic bias at the surfaces, corresponding to linear and quadratic solutal Marangoni effects. For purely diffusive transport, an increase in film thickness either exponentially decreases the lateral instability or entirely stabilizes the film. Including convective transport leads to a further destabilization as compared to the purely diffusive case. In some cases the inclusion of convective transport and the related widening of the range of available film configurations (it is then able to change its surface profile) change the stability behavior qualitatively. We furthermore present results regarding the dependence of the instability on several other parameters, namely, the Reynolds number, the Surface tension number and the ratio of the typical velocities of convective and diffusive transport.Comment: Published in Physics of Fluic

Large wind energy converter: Growian 3 MW

The main features of the Growian wind energy converter are presented. Energy yield, environmental impact, and construction of the energy converter are discussed. Reliability of the windpowered system is assessed

Seminar on the production, management and marketing of berryfruit

Seminar held by the Dept. of Horticulture in conjunction with the New Zealand Berryfruit Grower's Federation.The papers presented in this bulletin were delivered during a two day course for berryfruit growers preceding the annual conference of Growers' Federation and at a production and management field day Research Area, Lincoln College, the following day

Apple monitoring in Germany & the Netherlands: A whole systems approach to grower education & research

Twenty one Jonagold orchards in three regions of Germany and one in The Netherlands were monitored during the 1989 season for a range of biological, economic and management factors. Most orchards were 8 years old on MIX stock. Tree numbers varied between 1250 - 3472/ha and the selected orchards covered single and double row planting as well as 4, 5 and 6 row beds. Flower numbers varied between 0.95m and 5.27m/ha but often orchards with high flower numbers set a lower percentage of fruit. Fruit set varied between 7.5 and 34.1 %. Average fruit number/tree varied between 105 and 330. Average fruit weight on an orchard basis varied between 140 and 280g. Highest extrapolated yield was 92.2t/ha and the lowest 19t/ha. Gross margins varied markedly between districts mainly because of average price. The highest gross margin recorded was DM 62,000 per ha and the lowest DM 9800. Harvesting and marketing costs represented about 20% of total returns but chemical costs were less significant in the range 3.0 - 3.3% of total returns. Market prices on average were highest in the south of Germany (DM 0.82/kg) and lowest in The Netherlands (DM 0.48/kg). Detailed appendices are included setting out individual grower's spray and fertiliser programmes and labour and machinery inputs. Data is recorded on a per tree basis with the trees divided into 3 levels. The harvest data includes yield, fruit size, fruit colour, and rejects. Some data is supplied on terminal and lateral positions of the flower buds and subsequent fruiting. Analyses is given of various relationships, such as fruit number versus fruit size, and reasons for differences identified. The paper provides a basis for further development of this monitoring work to allow growers to improve their profitability by making management changes. It also identifies areas of research which are still needed to allow reliable predictive and explanatory apple tree models to be developed

Driving Rydberg-Rydberg transitions from a co-planar microwave waveguide

The coherent interaction between ensembles of helium Rydberg atoms and microwave fields in the vicinity of a solid-state co-planar waveguide is reported. Rydberg-Rydberg transitions, at frequencies between 25 GHz and 38 GHz, have been studied for states with principal quantum numbers in the range 30 - 35 by selective electric-field ionization. An experimental apparatus cooled to 100 K was used to reduce effects of blackbody radiation. Inhomogeneous, stray electric fields emanating from the surface of the waveguide have been characterized in frequency- and time-resolved measurements and coherence times of the Rydberg atoms on the order of 250 ns have been determined.Comment: 5 pages, 5 figure

Imaging electric fields in the vicinity of cryogenic surfaces using Rydberg atoms

The ability to characterize static and time-dependent electric fields in situ is an important prerequisite for quantum-optics experiments with atoms close to surfaces. Especially in experiments which aim at coupling Rydberg atoms to the near field of superconducting circuits, the identification and subsequent elimination of sources of stray fields is crucial. We present a technique that allows the determination of stray-electric-field distributions $(F^\text{str}_\text{x}(\vec{r}),F^\text{str}_\text{y}(\vec{r}),F^\text{str}_\text{z}(\vec{r}))$ at distances of less than $2~\text{mm}$ from (cryogenic) surfaces using coherent Rydberg-Stark spectroscopy in a pulsed supersonic beam of metastable $1\text{s}^12\text{s}^1~{}^{1}S_{0}$ helium atoms. We demonstrate the capabilities of this technique by characterizing the electric stray field emanating from a structured superconducting surface. Exploiting coherent population transfer with microwave radiation from a coplanar waveguide, the same technique allows the characterization of the microwave-field distribution above the surface.Comment: 6 pages, 4 figure

Management information systems for the horticultural firm

The development of micro computers has highlighted the need for accurate information at a property level in order to have suitable input data for planning and decision making. This review reveals limited research in developing horticultural information systems and a disappointing response from the farming community in various countries to a generalised recording scheme. Attempts to impose formalised recording schemes have suffered from lack of involvement of growers in the planning stage and limited · contact between advisers and growers after the information has been collated and returned. The Horticultural Management Information System developed by Carlsson and his co-workers in Sweden has received ready acceptance by growers. It seems that Calrsson is succeeding because he has compiled his information system with a close and frequent consultancy approach. The conclusions drawn in this review suggest that the simple intimate approach to information systems initially, lead to grower interest and increasing enthusiasm