Precoder Partitioning in Closed-loop MIMO Systems

We study unitary precoding for multistream MIMO systems with partial channel state information at the transmitter. We introduce a quantization scheme in which the full space of non-equivalent precoding matrices is partitioned into Grassmannian and orthogonalization parts. The Grassmannian part is used for maximizing the power after precoding and the orthogonalization part is used for removing cross talk between the data streams. We show that orthogonalization improves the attainable capacity when the receiver is linear. We give a parametrization for the non-equivalent orhogonalization matrices and a metric which measures the orthogonality of the transmission. Optimal orthogonalization codebooks for two-stream transmission are presented. When feedback is limited, the optimal partitioning of feedback bits between Grassmannian and orthogonalization parts becomes an issue. In correlated scenarios, the number of feedback bits may be significantly reduced by investing bits into the orthogonalization part.     

Determination of organic silicon compounds in biogas from wastewater treatments plants,landfills, and co-digestion plants

The study determined the organic silicon compounds in biogases from landfills, wastewater treatment plants (WWTPs), and biogas plants processing different organic material. The aim was to provide information for gas utilisation applications, as siloxanes are reported to shorten the life time of engines when biogas is used for energy production. In total, 48 samples were measured. The total concentration of organic silicon compounds in landfill and WWTP gases varied from 77 to 2460 μg/m³ while the concentrations in biogases from biogas plants varied from 24 to 820 μg/m³. The total concentration of organic silicon compounds was lowest (24 μg/m³) in the biogas plant processing grass and maize, and highest (2460 μg/m³) in one of the studied WWTP. The most common compounds in WWTPs and in biogas plants processing also sewage sludge were D4 and D5 while in landfills the most common compounds were D4 and L2 followed by trimethyl silanol. The effect of condensation of biogas on concentrations of organic silicon compounds was studied in one of the landfills and a negligible effect on concentrations was detected.     

The Potassium,Sodium, Magnesium,Calcium and Phosphate Nutrition of Sugarbeet (Beta vulgaris) Grown on Soils Containing Incorporated Straw

Between 1990 and 1992, a series of three experiments compared the effects of incorporating or removing straw from a total of five preceding cereal crops on the nutrient concentration, uptake and processing quality of sugarbeet. Incorporated straw increased K concentrations in tops and roots and increased total K uptake by c 40 kg ha^-1. Conversely, incorporated straw reduced Na concentrations and reduced total Na uptake by c 10 kg ha^-1. Straw incorporation had little effect on root processing quality, because whilst K impurities increased in the straw incorporated treatments, Na impurities were reduced. Generally, any effects of straw disposal method on concentration and uptake of phosphorus, calcium and magnesium were small and of little agronomic or economic significance. In the absence of regular soil analysis it is recommended that when straw has been incorporated that K fertiliser rates for beet are reduced by c 20 kg ha^-1. This is less than the allowance made for cereals. Also, contrary to the current cereal recommendation, there was no evidence for reducing P inputs when straw had been incorporated. © 1997 SCI.     

Influence of polymers on microstructure and adhesive strength of cementitious tile adhesive mortars

The impact of polymer modification on the physical properties of cementitious mortars is investigated using a multimethod approach. Special emphasis is put on the identification and quantification of different polymer components within the cementitious matrix. With respect to thin-bed applications, particularly tile adhesives, the spatial distributions of latex, cellulose ether (CE), polyvinyl alcohol (PVA), and cement hydration products can be quantified. It is shown that capillary forces and evaporation induce water fluxes in the interconnected part of the pore system, which transport CE, PVA, and cement ions to the mortar interfaces. In contrast, the distribution of latex remains homogeneous. In combination with results from qualitative experiments, the quantitative findings allow reconstruction of the evolution from fresh to hardened mortar, including polymer film formation, cement hydration, and water migration. The resulting microstructure and the failure modes can be correlated with the final adhesive strength of the tile adhesive. The results demonstrate that skinning prior to tile inlaying can strongly reduce wetting properties of the fresh mortar and lower final adhesive strength.     

Hygienic level and surface contamination in fresh-cut vegetable production plants

The number of vegetable processing plants has increased during recent years in many countries. At the same time, fresh vegetable products have been implicated by epidemiologic investigations as sources of infection. Fresh vegetables are susceptible to microbial contamination after harvest due to their high water and nutrient contents. Contamination may occur at all stages during production. The aim of this study was to determine the level of surface contamination after cleaning in several fresh-cut vegetable processing plants, and to identify the critical points in the processes and operating rooms. Surface and environmental samples were taken from the plants after cleaning of the processing devices and surfaces. The levels of surface and air hygiene in the vegetable processing factories were determined with different rapid hygiene monitoring methods. The amounts of total aerobic bacteria, Enterobacteriaceae and β-glucuronidase-positive bacteria, yeasts and moulds on surfaces were measured using Hygicult^® contact plates. ATP bioluminescence was measured luminometrically with an HY-LiTE^®2 equipment. The number of microbes in air was measured with an MAS-100 sampler. The highest levels of total aerobic bacteria, yeasts, Enterobacteriaceae and β-glucuronidase-positive bacteria were detected on machines (cutters, peeling machines etc.). High mean values of ATP were detected e.g. on packaging surfaces (due to high values of wooden boxes) and on cutters. Most of the bacterial counts measured on the surfaces were unacceptable when using the Finnish surface hygiene guidelines as criteria. However, the results should be examined in the context of the type of production and the stage of operation also must be taken into account. Different hygiene areas (FDA, 2008) should be separate enough to allow maintenance of good hygiene in cleaner areas while accepting lower hygiene levels e.g. in primary (early) washing steps. Despite this, the results show that there is a clear need to improve cleaning and hygiene practices in vegetable production. Several practical recommendations were given e.g. concerning cleaning, design of production areas, training of employees and self monitoring of surface hygiene. The information obtained will be used for improvement of practices in the cleaning of vegetable processing factories.     

How woodcocks produce the most brilliant white plumage patches among the birds

Until recently, and when compared with diurnal birds that use contrasting plumage patches and complex feather structures to convey visual information, communication in nocturnal and crepuscular species was considered to follow acoustic and chemical channels. However, many birds that are active in low-light environments have evolved intensely white plumage patches within otherwise inconspicuous plumages. We used spectrophotometry, electron microscopy, and optical modelling to explain the mechanisms producing bright white tail feather tips of the Eurasian woodcock Scolopax rusticola. Their diffuse reflectance was approximately 30% higher than any previously measured feather. This intense reflectance is the result of incoherent light scattering from a disordered nanostructure composed of keratin and air within the barb rami. In addition, the flattening, thickening and arrangement of those barbs create a Venetian-blind-like macrostructure that enhances the surface area for light reflection. We suggest that the woodcocks have evolved these bright white feather patches for long-range visual communication in dimly lit environments.     

Developing Cross-Cultural Communication Skills

Engineers have traditionally focused on hard-skill knowledge acquisition, but the increasingly multicultural work practices of professional engineers now demand better soft-skill proficiency, such as foreign language ability, communication confidence, and cross-cultural experience. Students and staff within a university engineering department were surveyed to identify how cross-cultural language use potentially impacted academic and communication performance. The results indicate that engineering faculties may be concentrating on subject content at the expense of facilitating the development of soft skills. The findings suggest that students do experience problems with communication skills that may be exacerbated when studying in a second language. Lecturers need to become more energized to introduce innovative curriculum schemes, more proactive in developing challenging learning approaches, and more willing to integrate cross-cultural, language, and communication skills training into traditional engineering contexts. This case study has implications for any university engineering department where students are taught either partially or solely in a second language and where issues of communication and culture are recognized as impacting the professional development of engineers for the global workplace.     

Square-matrix embeddable space-time block codes for complex signalconstellations

Space-time block codes for providing transmit diversity in wireless communication systems are considered. Based on the principles of linearity and unitarity, a complete classification of linear codes is given in the case when the symbol constellations are complex, and the code is based on a square matrix or restriction of such by deleting columns (antennas). Maximal rate delay optimal codes are constructed within this category. The maximal rates allowed by linearity and unitarity fall off exponentially with the number of transmit antennas     

Social support and the quality of parenting under economic pressure and workload in Finland: The role of family structure and parental gender.

This study focused on how factors outside the home affect the quality of mothering and fathering. Economic pressure and workload were evaluated along with the compensating role of social support on parenting. Information was gathered from 842 mothers and 573 fathers including 139 single-mother and 21 single-father families. The results showed that the nature of the strains, together with parental gender and family structure, influenced their effects on parenting. The results further revealed some gender- and strain-specific protective functions of social support on parenting. For example, economic pressure was related to increased punitive parenting, which was compensated by instrumental and emotional support among the mothers. Workload was related to less authoritative single fathering, which was compensated by instrumental support. (PsycINFO Database Record (c) 2010 APA, all rights reserved)