Campus Ciudad Juarez

This work examines whether stepwise discriminant function analysis of a suite of craniodental variables enables feeding behaviour and habitat preferences to be identi®ed in fossil ungulates. There are several morphological features of the ungulate skull, mandible and dentition that are well correlated with dietary adaptations, and thus can be used for estimating the feeding ecology of extinct taxa. However, most studies have followed an univariate approach for characterizing the relationship between diet and craniodental structure in extant ungulates (but see Pe Ârez-Barberia & Gordon, 2001), even though such a relationship has been revealed to be complex because of functional, phylogenetic and biomechanical constraints. In this paper a multivariate perspective is followed, developing quadratic discriminant functions for pairwise comparisons of dietary/habitat groups in modern species. Given that the stepwise method for selecting the morphological variables to be included in the algorithms was used, alternative discriminant functions are provided. Results obtained show that these algorithms reclassify correctly the species according to their feeding and habitat ecology, and thus may be useful for obtaining reliable palaeoautecological inferences (i.e. those related to the life style of extinct species, such as feeding ecology and habitat preferences) when applied to extinct ungulate taxa.

Questions: Are different types of terrestrial mammalian-dominated ecosystems characterized by specific taxon-free patterns in the trophic structure of the mammalian community? If so, are these patterns an intrinsic property of the ecosystems? If this is indeed true, the trophic structure of present-day mammalian communities can be used for the synecological reconstruction of past terrestrial mammalian-dominated communities. Data: 110 Recent large mammal communities, 86 from Africa and 24 from Asia, and one large mammal assemblage from the early Pleistocene locality at Venta Micena (Guadix-Baza Basin, southeast Spain). Search method: Stepwise discriminant analysis generated mathematical algorithms that characterize definite patterns in the trophic structure of the mammalian communities from each type of ecosystem. Algorithms adjusted with African communities were applied to the Asian and Pleistocene ones, whose species are completely different from those of Africa, to test if these patterns are independent of specific historical circumstances and taxonomic composition. Conclusions: Terrestrial mammalian-dominated ecosystems are characterized by definite taxon-free patterns in the trophic structure of the mammalian community. These patterns are an intrinsic property of the ecosystems, independent of their specific historical circumstances and taxonomic composition. Therefore, the trophic structure of present-day mammalian communities can be used for the synecological reconstruction of past ones. The sedimentologic and taphonomic information for the early Pleistocene community of Venta Micena is indicative of a wooded savanna; this type of ecosystem is also indicated by the trophic structure of the mammalian community. This congruence supports the hypothesis that the ecological patterns identified here are an intrinsic property of past ecosystems, at least as far as Pleistocene land mammal-dominated communities are concerned.

Estimating the body mass of extinct ungulates: a study on ... M. Mendoza1,2, CM Janis1 & P. Palmqvist2 ... 1 Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA 2 Departamento de Ecologıa y Geologıa, Facultad de Ciencias, ...

The main objective of this thesis is the characterization of a horizontal ground heat pump system. The characterization consists on (a) the design of a real-time and continuous coefficient of performance (COP) and energy efficiency rate (EER) calculation model, (b) the determination of the heat rejected to the ground (total and per pipe length unit) and (c) the 2D ground temperature profile determination. One instrumentation methodology and five programs were developed in order to meet these objectives as shown in the next figure. A ground source heat pump system has been installed and tested at the Research Group on Sustainable Edification & Low Temperature Geothermic Studies test room (Escamilla’s Field Igloo), Tecnológico de Monterrey, Monterrey campus, Mexico. The models developed for the construction of the programs, the results obtained and the experimental validation of these results are presented and discussed. The performance parameters were compared statistically versus an analytical model that calculates the four thermodynamic states of the system using characteristic data inputs. The heat rejection to the ground and the temperature profile routines were programmed using a horizontal numerical model solved using a simplified finite difference approximation. It was observed that the complete characterization meets the experimental results.

Greenhouse structures have demonstrated success enhancing crop yields in farmlands, but the energy for thermal control and lighting make them impractical in cold weather locations because traditional greenhouse construction techniques result in a trade-off between light transmission and thermal insulation. The objective of the project described in this dissertation was to conceptualize, design and test a practical solution to the light transmission and thermal insulation trade-off challenge. The system that was developed is a variable light valve system that can be switched between two states – in one state the system acts as a sunlight transparent window and the other state the system acts as a highly thermally insulated ceiling capable of keeping the structure warm in cold weather conditions. Switching between the two states requires only a simple, low-cost rotation mechanism. The possibility of extending the hours of operation for the light valve system by adjusting the angular position of its light valve elements was also explored.
The light valve system when in its highly thermally insulated state, demonstrated a thermal insulation value above 3.33 m²K/W and 70% light transmittance when in its light transmissive state. In order to achieve this thermal insulation value, air mass transfer losses through the light valve structure were reduced by the implementation of low pressure seal. The experimental devices used to test the light valve system demonstrated it can be constructed using inexpensive and readily available materials. The project described in this dissertation has successfully confirmed a practical solution to reduce the energy use for heating in cold climate greenhouses while maintaining appropriate sunlight transmittance through their structure. The light valve system may represent a practical alternative for cold climate greenhouse horticulture.

Greenhouse structures are widely used to enable sheltered plant growth. However, traditional transparent greenhouse structures are generally only used in moderate climates because the cost of the energy required for heating in cold climates is prohibitively high. This paper describes a new approach to the design trade-off between light transmission and thermal insulation in greenhouse structures. Here, a low power variable insulation system combining sunlight-concentrating structures and low cost thermal insulation is shown to be a potentially practical solution. Experimental devices have achieved thermal insulation values exceeding 3.33 m 2 K/W (compared to 0.42 m 2 K/W for triple layer polycarbonate greenhouses) while also maintaining light transmittance values greater than 70%.

This paper describes a solar tracking system designed to operate at the specified coordinates in the methodology used to calculate the position of the sun, which can be changed to make the system work at any desired location, These data are used to program the solar tracker which remain oriented a concentration photovoltaic solar cell at 90° with respect to the position of the sun, this to increase the amount of sunlight captured by the system, thus increased the efficiency of the system, the proposed solar tracking system is a system based in the solar passive design, and do not use photovoltaic sensor, but a database in which are contained the calculated positions of the sun for each hour of the day, for each day of the year this database is contained in a programmable microcontroller which directs the solar panel through motors to the desired position the system data are compared against a motionless solar cell of the same characteristics, obtaining higher voltages in the system with the solar tracker.

Header Files.-Son las librerías, es decir, son archivos donde especifican para que sirvan los comandos que usas. Por ejemplo, en la librería conio.h viene como funciona el clrscr.. si no pones la librería entonces cuando usas clrscr no funciona el programa, pues no está asociada dicha instrucción.