Single-Change Circular Covering Designs

A single-change circular covering design (scccd) based on the set [v] = {1, . . . ,v} with block size k is an ordered collection of b blocks, B = {B1, . . . ,Bb}, each Bi ⊂ [v], which obey: (1) each block differs from the previous block by a single element, as does the last from the first, and, (2) every pair of [v] is covered by some Bi. The object is to minimize b for a fixed v and k. We present some minimal constructions of scccds for arbitrary v when k = 2 and 3, and for arbitrary k when k+1 ≤ v ≤ 2k. Tight designs are those in which each pair is covered exactly once. Start-Finish arrays are used to construct tight designs when v \u3e 2k; there are 2 non-isomorphic tight designs with (v, k) = (9, 4), and 12 with (v, k) = (10, 4). Some non-existence results for tight designs, and standardized, element-regular, perfect, and column-regular designs are also considered

Linear and Circular Single Change Covering Designs Re-visited

A \textbf{single change covering design} is a $v$-set $X$ and an ordered list \cL of $b$ blocks of size $k$ where every $t$-set must occur in at least one block. Each pair of consecutive blocks differs by exactly one element. A single change covering design is circular when the first and last blocks also differ by one element. A single change covering design is minimum if no other smaller design can be constructed for a given $v, k$. In this paper we use a new recursive construction to solve the existence of circular \sccd($v,4,b$) for all $v$ and three residue classes of circular \sccd($v,5,b$) modulo 16. We solve the existence of three residue classes of \sccd$(v,5,b)$ modulo 16. We prove the existence of circular \sccd$(2c(k-1)+1,k,c^2(2k-2)+c)$, for all $c\geq 1, k\geq2$, using difference methods.Comment: 23 pages, 15 Table

Solar stills:a comprehensive review of designs, performance and material advances

The demand for fresh water production is growing day by day with the increase in world population and with industrial growth. Use of desalination technology is increasing to meet this demand. Among desalination technologies, solar stills require low maintenance and are readily affordable; however their productivity is limited. This paper aims to give a detailed review about the various types of solar stills, covering passive and active designs, single- and multi-effect types, and the various modifications for improved productivity including reflectors, heat storage, fins, collectors, condensers, and mechanisms for enhancing heat and mass transfer. Photovoltaic-thermal and greenhouse type solar stills are also covered. Material advances in the area of phase change materials and nanocomposites are very promising to enhance further performance; future research should be carried out in these and other areas for the greater uptake of solar still technology

Integrating photovoltaic cells into decorative architectural glass using traditonal glasspainting techniques and fluorescent dyes

Photovoltaic cells can be integrated into decorative glass, providing a showcase for this renewable technology, whilst assisting in the creation of sustainable architecture through generation of electricity from the building surface. However, traditional, opaque, square, crystalline-silicon solar cells contrast strongly with their surroundings when incorporated into translucent, coloured glazing. Methods of blending photovoltaic cells into their surroundings were developed, using traditional glass painting techniques. A design was created in which opaque paint was applied to the areas of glass around underlying photovoltaic cells. Translucent, platinum paint was used on the glass behind the photovoltaic cells. This covered the grey cell backs whilst reflecting light and movement. The platinum paint was shown to cause a slight increase in power produced by photovoltaic cells placed above it. To add colour, very small amounts of Lumogen F dye (BASF) were incorporated into a silicone encapsulant (Dow Corning, Sylgard 184), which was then used hold photovoltaic cells in place between sheets of painted glass. Lumogen dyes selectively absorb and emit light, giving a good balance between colour addition and electricity production from underlying photovoltaic cells. When making sufficient quantities of dyed encapsulant for a 600 x 450 mm test piece, the brightness of the dye colours faded, and fluorescence decreased, although some colour was retained. Improvement of the method, including testing of alternative encapsulant materials, is required, to ensure that the dyes continue to fluoresce within the encapsulant. In contrast, the methods of adding opacity variation to glass, through use of glass painting, are straightforward to develop for use in a wide variety of photovoltaic installations. Improvement of these methods opens up a wide variety of architectural glass design opportunities with integrated photovoltaics, providing an example of one new medium to make eco-architecture more aesthetically pleasing, whilst generating electricity

Mechanically tunable optofluidic distributed feedback dye laser

A continuously tunable optofluidic distributed feedback (DFB) dye laser was demonstrated on a monolithic replica molded poly(dimethylsiloxane) (PDMS) chip. The optical feedback was provided by a phase-shifted higher order Bragg grating embedded in the liquid core of a single mode buried channel waveguide. Due to the soft elastomeric nature of PDMS, the laser frequency could be tuned by mechanically stretching the grating period. In principle, the mechanical tuning range is only limited by the gain bandwidth. A tuning range of nearly 60nm was demonstrated from a single dye laser chip by combining two common dye molecules Rhodamine 6G and Rhodamine 101. Single-mode operation was maintained with less than 0.1nm linewidth. Because of the higher order grating, a single laser, when operated with different dye solutions, can provide tunable light output covering the entire spectrum from near UV to near IR in which efficient laser dyes are available. An array of five DFB dye lasers with different grating periods was also demonstrated on a chip. Such tunable integrated laser arrays are expected to become key components in inexpensive advanced spectroscopy chips

Mission Concept for the Single Aperture Far-Infrared (SAFIR) Observatory

The Single Aperture Far-InfraRed (SAFIR) Observatory's science goals are driven by the fact that the earliest stages of almost all phenomena in the universe are shrouded in absorption by and emission from cool dust and gas that emits strongly in the far-infrared and submillimeter. Over the past several years, there has been an increasing recognition of the critical importance of this spectral region to addressing fundamental astrophysical problems, ranging from cosmological questions to understanding how our own Solar System came into being. The development of large, far-infrared telescopes in space has become more feasible with the combination of developments for the James Webb Space Telescope and of enabling breakthroughs in detector technology. We have developed a preliminary but comprehensive mission concept for SAFIR, as a 10 m-class far-infrared and submillimeter observatory that would begin development later in this decade to meet the needs outlined above. Its operating temperature (<4K) and instrument complement would be optimized to reach the natural sky confusion limit in the far-infrared with diffraction-limited peformance down to at least 40 microns. This would provide a point source sensitivity improvement of several orders of magnitude over that of Spitzer or Herschel, with finer angular resolution, enabling imaging and spectroscopic studies of individual galaxies in the early universe. We have considered many aspects of the SAFIR mission, including the telescope technology, detector needs and technologies, cooling method and required technology developments, attitude and pointing, power systems, launch vehicle, and mission operations. The most challenging requirements for this mission are operating temperature and aperture size of the telescope, and the development of detector arrays.Comment: 36 page

Home and community based parenting support programmes and interventions: report of Workpackage 2 of the DataPrev project

The last decade has witnessed an increasing interest in the promotion of mental health and wellbeing because of its importance for health and social functioning at the individual level and for the social and economic wellbeing of societies. Recent research from a range of disciplines has highlighted the importance of the quality of the parent-child relationships and parenting on children‟s emotional and social development, and on adult mental health and wellbeing. Intervention studies involving children of all age groups have shown that if parenting can be influenced for the better outcomes can be changed. The DataPrev project was funded by the 6th Framework of the European Community Research Programme under Policy-Orientated Research with the aim of establishing a database of evidence-based programmes in Europe that promote mental health and wellbeing and prevent mental illness throughout the life course. This is the report of the Workpackage 2 describing the international evidence base on programmes to support parenting, including home and community based programmes