The avalanche monitoring system av mount Pizzac

The monitoring system of Mount Pizzac has been created in order to study the avalanche dynamics and the effect of its impact on the structures. In its extreme dimensions the monitored avalanche gets off at 2200 meters and stops at 1745 meters, thus following a trajectory of 836 meters with an average gradient of 310. The necessary structures for monitoring have been installed in the track of the gully between the above limit of the flowing zone and the central track of the accumulation zone, for a whole length of 418 meters. They allow to observe the development of the event, thus recording continuously: pressures, speed and geometric variations of the body of the avalanche. In particular six steel poles, each one fitted out with n. 8 pressure measuring devices (each one with an area of 7850 mm") allow to determine the profile of the pressures continually with a resolution of 50 em up to a maximum height of 5 m. Moreover, five of the six poles placed along the flowing zone of the avalanche are fitted out with measuring devices able to check the flow height, allowing the recreation both in time and space. A small-sized wedge-shaped obstacle (area 1 m-) allows to estimate the influence of the form and area over the power of the avalanche impact. Furthermore, knowing the time when the avalanche flow passes by means of sections placed at known distances, it is possible to determine the average speed of the front in 14 tracks of the flow line. The monitoring system has three cameras which permit to record the event automatically. 15 events have been recorded since 1993, when the monitoring system was first installed. The avalanches which occured most frequently were wet snow flowing avalanches in springtime and dry snow flowing avalanches in wintertime, with average volumes of 2000 m", Particularly for average speeds of the avalanche front ranging from 2.5 to 23 m/s, the pressures have recorded variable readings going from 5 to 175 kPa

¿Cómo medir el subsidio soviético a la economía cubana? Una nueva propuesta

Trade between the former Soviet Union (USSR) and Cuba during the period before the collapse of the Socialist bloc has been the subject of many studies, which have attempted to quantify that commerce in US dollars without taking into account the peculiarities of the relations between the Socialist countries that were members of the Council for Mutual Economic Assistance (CMEA). This research has drawn on official sources (from the Office of Statistics and the Banco Nacional de Cuba) to remedy the methodological errors that result from overlooking those peculiarities, and proposes a new metric for the aid received by Cuba from the USSR.El comercio entre la ex Unión Soviética (URSS) y Cuba hasta el derrumbe del campo socialista, ha sido objeto de numerosos estudios que lo han tratado de medir en dólares estadounidenses, sin tomar en cuenta las peculiaridades de las relaciones entre los países socialistas miembros del CAME (Consejo de Ayuda Mutua Económica). En este trabajo, utilizando fuentes oficiales (de la oficina de estadística y del Banco Nacional de Cuba), tratamos de subsanar los errores metodológicos cometidos, proponiendo una nueva medición de la ayuda soviética a Cuba

Looking beyond the powder/dense flow avalanche dichotomy

Köhler et al. (2018) deploy a high spatial and temporal resolution GEODAR radar system to reveal the inside of snow avalanches over the entire slope. They detect a rich variety of longitudinal and slope normal flow structures across a data set of 77 avalanches recorded over 6 years. Distinctive features in the radar signatures permit the definition of seven flow regimes and three distinct stopping signatures, illustrating behaviours much richer than the conventional dichotomy between dense flow avalanches and powder snow avalanches. This presents modellers with the challenge of exploring the physics of these regimes, the transitions between them and their relationship with the surrounding conditions

Crisis del modelo neoliberal y perspectivas para la economía mexicana

Hace más de 2 décadas en México se empezó a dar un cambio radical en el modelo económico. La economía mexicana, que se había caracterizado en la década de los 70 por un bajo grado de apertura, se convirtió entre los años 80 y 90 en una de las  economías más abiertas de la OCDE, como consecuencia del ingreso del país al GATT (1986), y de la entrada en vigordel TLCAN (1994). Asi mismo una economía muy controlada por el estado por medio de una gran cantidad de empresas paraestatales, se transformó en una economía de mercado casi “pura”, por efecto de un masivo proceso de privatización1 , a raíz del cual solo quedan dos grandes empresas públicas, ambas en el sector energético (PEMEX y CFE). Los resultados no son tan alentadores: la tasa de crecimiento real del PIB en los últimos 20años ha sido netamente inferior a la de las dos décadas anteriores, las diferencias sociales siguen enormes, los indicadores de justicia distributiva no han mejorado de manera significativa así como los índices de pobreza.En los últimos años se han agudizado algunos desequilibrios, tanto internos como externos, que obligan a una reflexión sobre los cambios necesarios en el modelo económico. En esesentido México se enfrenta a una encrucijada, donde se vislumbran dos posibles escenarios: el primero es el de las reformas estructurales, entendidas como agudización del modelo neoliberal dominante, el segundo es el de un cambio de modelo o de una sustancial modificación del actual

The dynamics of surges in the 3 February 2015 avalanches in Vallee de la Sionne

Five avalanches were artificially released at the Vallée de la Sionne test site in the west of Switzerland on 3 February 2015 and recorded by the GEOphysical flow dynamics using pulsed Doppler radAR Mark 3 radar system. The radar beam penetrates the dilute powder cloud and measures reflections from the underlying denser avalanche features allowing the tracking of the flow at 111 Hz with 0.75 m downslope resolution. The data show that the avalanches contain many internal surges. The large or “major” surges originate from the secondary release of slabs. These slabs can each contain more mass than the initial release, and thus can greatly affect the flow dynamics, by unevenly distributing the mass. The small or “minor” surges appear to be a roll wave-like instability, and these can greatly influence the front dynamics as they can repeatedly overtake the leading edge. We analyzed the friction acting on the fronts of minor surges using a Voellmy-like, simple one-dimensional model with frictional resistance and velocity-squared drag. This model fits the data of the overall velocity, but it cannot capture the dynamics and especially the slowing of the minor surges, which requires dramatically varying effective friction. Our findings suggest that current avalanche models based on Voellmy-like friction laws do not accurately describe the physics of the intermittent frontal region of large mixed avalanches. We suggest that these data can only be explained by changes in the snow surface, such as the entrainment of the upper snow layers and the smoothing by earlier flow fronts

Regional evaluation of three day snow depth for avalanche hazard mapping in Switzerland

The distribution of the maximum annual three day snow fall depth <i>H<sub>72</sub></i>, used for avalanche hazard mapping according to the Swiss procedure (<i>Sp</i>), is investigated for a network of 124 stations in the Alpine part of Switzerland, using a data set dating back to 1931. Stationarity in time is investigated, showing in practice no significant trend for the considered period. Building on previous studies about climatology of Switzerland and using an iterative approach based on statistical tests for regional homogeneity and scaling of <i>H<sub>72</sub></i> with altitude, seven homogenous regions are identified. A regional approach based on the index value is then developed to estimate the <i>T</i>-years return period quantiles of <i>H<sub>72</sub></i> at each single site <i>i</i>, <i>H<sub>72i</sub>(T)</i>. The index value is the single site sample average μ<sub><i>H<sub>72i</sub></i></sub>. The dimensionless values of <i>H<sup>*</sup><sub>72i</sub>=H<sub>72i</sub> / μ<sub>H<sub>72i</sub></sub></i> are grouped in one sample for each region and their frequency of occurrence is accommodated by a General Extreme Value, GEV, probability distribution, including Gumbel. The proposed distributions, valid in each site of the homogeneous regions, can be used to assess the <i>T</i>-years return period quantiles of <i>H<sup>*</sup><sub>72i</sub></i>. It is shown that the value of <i>H<sub>72i</sub>(T)</i> estimated with the regional approach is more accurate than that calculated by single site distribution fitting, particularly for high return periods. A sampling strategy based on accuracy is also suggested to estimate the single site index value, i.e. the sample average μ<sub><i>H<sub>72i</sub></i></sub>, critical for the evaluation of the distribution of <i>H<sub>72i</sub></i>. The proposed regional approach is valuable because it gives more accurate snow depth input to dynamics models than the present procedure based on single site analysis, so decreasing uncertainty in hazard mapping procedure

High-resolution radar measurements of snow avalanches

Two snow avalanches that occurred in the winter 2010-2011 at Vallée de la Sionne, Switzerland, are studied using a new phased array FMCW radar system with unprecedented spatial resolution. The 5.3 GHz radar penetrates through the powder cloud and reflects off the underlying denser core. Data are recorded at 50 Hz and have a range resolution better than 1 m over the entire avalanche track. We are able to demonstrate good agreement between the radar results and existing measurement systems that record at particular points on the avalanche track. The radar data reveal a wealth of structure in the avalanche and allow the tracking of individual fronts and surges down the slope for the first time. Key Points Validation between our radar results and existing point measurement systems High-resolution radar allows tracking of fronts and surges from start to finish Velocity linked with topography may be used to measure rheology of snow ©2013. American Geophysical Union. All Rights Reserved

Taking Into Account Wet Avalanche Load for the Design of Pylon-like Structures.

Wet snow avalanches interact with infrastructures around the world but their significance on the structure design is frequently neglected due to the low velocity, which characterize the flow and thus the expected low impact pressures. Recent pressure measurements performed at the Swiss Vallée de la Sionne full-scale test site show that wet avalanche pressures, measured on a 20 m high tower, are considerably higher than those predicted by conventional avalanche engineering guidelines, thus potentially becoming relevant for the design of tower-like structures. In order to understand under which circumstances wet avalanches can become more relevant than their dry counter part and in order to establish simple rules to evaluate the pressure the avalanche exerts on a tower-like object, we analyse pressure and velocity data collected at the Vallée the la Sionne on obstacles of different shape and dimension

La reforma energética y el problema petrolero en México

After the Mexican oil expropriation, Petróleos Mexicanos (PEMEX) initially experienced the take-off of the industrial sector; but, since the 1970s, the company has mainly served two purposes: to make a profit and to contribute to fund government spending through taxes. Today, this oil company is facing a deep crisis. The aim of this study is to shed light on the origins of the current energy crisis of the country and propose different possibilities to address it. Using official data provided by the INEGI and PEMEX, we found that, in recent decades, the public finances in Mexico have greatly depended on oil revenue and, as a consequence, PEMEX has not been able to carry out the investment projects needed to maintain or increase their production. This has contributed to further the production decline, creating the right circumstances for an energy reform that attracts private investors to this sector. We conclude that a possible alternative to avoid the privatization of such a strategic natural resource as oil is passing a tax reform that increases non-oil-related tax revenue, thus enabling PEMEX to fund the investments needed to tackle the production decline.Desde la expropiación petrolera, y durante varias décadas, Petróleos Mexicanos (PEMEX) venía soportando el despegue del sector industrial. Así, a partir de los años 70 ha cumplido principalmente con dos funciones: generar divisa y contribuir en la financiación del gasto público a través del pago de impuestos. Hoy, sin embargo, la empresa petrolera enfrenta una crisis profunda. El objetivo de este trabajo es aclarar cómo se produjo la actual crisis energética por la que atraviesa el país, e indicar otros posibles caminos para afrontarla.  Utilizando datos oficiales del Instituto Nacional de Estadística y Geografía y de PEMEX se encuentra que en las últimas décadas las finanzas públicas han dependido, en gran medida, de los ingresos petroleros y, como consecuencia, PEMEX no ha podido llevar a cabo los proyectos de inversión necesarios para mantener o incrementar la producción. Como resultado, se ha exacerbado el declive de la producción, lo que ha creado las condiciones para la reforma energética a fin de atraer la inversión privada en este sector. Se concluye que una posible alternativa para evitar la privatización de un recurso natural tan estratégico como el petróleo sería aprobar una reforma fiscal que aumente los ingresos tributarios no petroleros, permitiéndole a PEMEX financiar la inversión necesaria para contrarrestar la caída de la producción