8,290 research outputs found
The down operator and expansions of near rectangular k-Schur functions
We prove that the Lam-Shimozono "down operator" on the affine Weyl group
induces a derivation of the affine Fomin-Stanley subalgebra of the affine
nilCoxeter algebra. We use this to verify a conjecture of Berg, Bergeron, Pon
and Zabrocki describing the expansion of k-Schur functions of "near rectangles"
in the affine nilCoxeter algebra. Consequently, we obtain a combinatorial
interpretation of the corresponding k-Littlewood--Richardson coefficients
Partial Classification of Lorenz Knots: Syllable Permutations of Torus Knots Words
We define families of aperiodic words associated to Lorenz knots that arise
naturally as syllable permutations of symbolic words corresponding to torus
knots. An algorithm to construct symbolic words of satellite Lorenz knots is
defined. We prove, subject to the validity of a previous conjecture, that
Lorenz knots coded by some of these families of words are hyperbolic, by
showing that they are neither satellites nor torus knots and making use of
Thurston's theorem. Infinite families of hyperbolic Lorenz knots are generated
in this way, to our knowledge, for the first time. The techniques used can be
generalized to study other families of Lorenz knots
Web Acceptance and Usage Model: A Comparison between Goal-directed and Experiential Web Users
In this paper we analyse the Web acceptance and usage between goal-directed users and experiential users, incorporating intrinsic motives to improve the particular and explanatory TAM value –traditionally related to extrinsic motives-. A field study was conducted to validate measures used to operationalize model variables and to test the hypothesised network of relationships. The data analysis method used was Partial Least Squares (PLS).The empirical results provided strong support for the hypotheses, highlighting the roles of flow, ease of use and usefulness in determining the actual use of the Web among experiential and goal-directed users. In contrast with previous research that suggests that flow would be more likely to occur during experiential activities than goal-directed activities, we found clear evidence of flow for goal-directed activities. In particular the study findings indicate that flow might play a powerfulrole in determining the attitude towards usage,intention to useand, in turn,actual Web use among experiential and goal-directed users
Refrigeration Capacity and Effect of Ageing on the Operation of Cellulose Evaporative Cooling Pads, by Wind Tunnel Analysis
This study investigates the temperature reduction capacity and water consumption of a
fan-pad system installed in a greenhouse located in the coastal regions of AlmerÃa. The suitability
of this system for coastal zones with high environmental humidity during the summer is analyzed.
Historical temperature and relative humidity series are studied, obtaining the thermal difference and
maximum, medium, and minimum monthly water consumption of the pads based on the operation
data of the pads. Despite the high relative humidity of the air in the hottest hours of the day, a
decrease of 5.92 ºC in the mean temperature and a water consumption of 13.55 l/h per square meter
of an evaporative cooling pad are obtained in the month of August. Additionally, the operation of a
cellulose evaporative cooling pad installed for 3 years in a greenhouse is analyzed in a wind tunnel
and compared with that of a new pad of the same model. Over time and with low maintenance,
the porosity of the pad decreases due to salt incrustation. The salt incrustation makes airflow more
difficult in the pad, increasing the pressure drop by 170.04%; however, the air saturation efficiency of
the pad increases by 6.6% due to the greater contact time between the air and the waterMinisterio de EconomÃa y Competitividad de España AGL2015-68050-RUnión Europea (FEDER) AGL2015-68050-
Assessment of the cooling potential of an indoor living wall using different substrates in a warm climate
The use of vertical greenery systems in buildings is becoming very popular as they provide several benefits. In this work, the influence of an indoor living wall on the temperature and humidity in a hall inside the School of Agricultural Engineering (University of Seville) was studied. Four different substrates, Geotextile, Epiweb, Xaxim and coconut fibre, were used to grow the plants in order to assess their performance. Several parameters such as temperature, humidity, plant growth or water consumption were monitored and analyzed during a 4-month period. The cooling effect of the living wall was proven, with an average reduction of 4°C over the room temperature though maximum decrements of 6°C have been observed in warmer conditions. Higher air humidity levels were experienced near the living wall, increasing the overall humidity in the room. All the substrates tested were suitable for plant growing and their behaviour was similar. Geotextile showed the best cooling capacity but higher water consumption, coconut fibre presented degradation problems and Epiweb performance was the poorest. Therefore, these systems have been proven to be very useful and interesting for warm indoor environments due to the cooling effect observed in addition to their bio-filtration capacity and the aesthetic component
- …