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[en] This paper presents the results of the three-dimensional (3D) discrete element method (DEM) simulations of undrained axisymmetric/triaxial tests on loose assemblies of polydisperse spheres with and without preshearing history using a periodic cell. Undrained tests are modelled by deforming the samples under constant volume conditions. The simulations show that the preshearing process will not induce initial structural anisotropy, and that the presheared and unpresheared samples follow the same initial stress path along a unique limiting boundary in the q–p space, as observed in the published experimental literature, which was not crossed over by any of the stress paths of the presheared samples. It is also shown that the presheared samples are denser compared with the original unpresheared one, and therefore exhibit higher resistance to (temporary) liquefaction. At the grain scale, such higher resistance is found to be attributed to the evolution of a redundancy factor, a microscopic definition of liquefaction (temporary liquefaction). The Lade instability (peak deviator stress) is found to correspond to a unique mechanical coordination number of 4.5, independent of preshearing history. It is also found that the onset of liquefaction (temporary liquefaction) in terms of the redundancy factor lags behind the onset of macroscopic strain softening in terms of the Lade instability for the presheared and unpresheared samples under undrained conditions. (paper)
[en] Maintenance involves maintaining and securing the equipment and systems in, or restoring them to, a state in which they can perform the required functions. The challenge for maintenance planning is to identify appropriate objects and tasks for preventive maintenance and ensure that there are adequate resources for the repair actions. In this paper we will present a maintenance planning approach, called value-driven maintenance planning (VDMP), to emphasise the fact that the objectives of the plant are the reference points for specifying functional requirements for the equipment locations and equipment. The three basic phases of the VDMP planning approach are: (i)the definition of the fundamental, strategic and maintenance (means) objectives of the production plant, (ii)the classification of equipment locations (including one or several equipment items) into maintenance classes, each associated with a functional requirement specification, and (iii)the selection of maintenance strategies and maintenance tasks (including timing) for equipment assigned to the equipment locations. Feedback of the operational experience is crucial for the application of the maintenance planning approach. As a consequence, the approach is developed to support the continuous improvement of the cost effectiveness of maintenance rather than planning of the initial maintenance programme of a new plant. Analysis techniques are presented and challenges of application are discussed. The application of the VDMP approach to a gasification plant in Finland is also presented
[en] Efficient use of ohmic heating in the drying zone of the plasma shaft furnace for gasification of organic and technogenic wastes is studied. It is shown that by using ohmic heating in the drying zone, energy release takes place in the filling along the entire zone. (paper)
[en] Highlights: • Novel study to evaluate the effect of food waste liquefaction on biodegradability. • Energy efficiency of 11.1 kg SCOD/kWh was optimum for combinative liquefaction. • Cost spent to attain 20–40% liquefaction was very low compared to others. • No significant difference in biodegradability for samples with 40–60% liquefaction. • Achievement of 40% liquefaction was beneficial in terms of energy and cost. - Abstract: In the present study, a new and novel attempt was made to investigate the effect of liquefaction (20–60%) on energy efficient gaseous biofuel recovery and cost during chemo thermo disperser liquefaction of food waste (CTDL). The outcome of the study revealed that rpm (10,000), specific energy input (174 kJ/kg TS), disintegration time (5 min) and energy efficiency of about 11.1 kg SCOD/KWh were considered as optimum in terms of energy and cost. The cost incurred to achieve 20–40% liquefaction was estimated to be 0.0132–0.0168 USD and found to be comparatively very low than the cost incurred (0.0367–0.0547) to achieve 50–60% liquefaction. The biodegradability results showed that a significant increment in biodegradability was achieved (from 0.26 gCOD/gCOD to 0.8 gCOD/gCOD) when the liquefaction was increased from 30 to 40% and an insignificant increment in biodegradability (from 0.8 gCOD/gCOD to 0.84 gCOD/gCOD) was achieved when the liquefaction was increased from 40 to 60%, respectively. The impact of liquefaction on energy balance and cost at tonnage level revealed that 40% liquefaction was considered to be profitable with energy ratio and net profit of about 1.12 and 93 USD/Ton, respectively.
[en] The post liquefaction behavior of buried conduits is analyzed and sensitivity analysis is conducted to investigate the damage potential of the forces induced in the buried lifelines following seismically induced liquefaction of the surrounding soil. Various lifeline configurations and loading conditions are considered. The loading conditions considered are: buoyancy forces and permanent ground displacements parallel to the lifeline axis. Pertinent parameters for the soil-lifeline interaction following liquefaction are identified. (author)
[en] Full text: The field of cryogenics deals with the study of low temperature processes. For the analysis of these processes there are used both the methods and laws of thermodynamics of macroscopic systems and the methods and laws which are at the basis of magneto-caloric phenomena in certain substances and in certain physical conditions of mass of those substances and of the environment. The most important elements which have to be taken into consideration when talking about this field are: liquefactors or cryogenerators, energy and safety. The project C43 represents a continuation of the work done previously by several institutions in the field of cryogenics and of material behaviour at cryogenic temperatures and has as the main objective the creation of an integrated platform for the study of cryogenic processes. The studies will be performed both from the point of view of installations, cryogenic cycles and direct use of cryogenic products and for the obtaining of experimental data at interdisciplinary level. The project C43 generated a complex integrated system (institutes, laboratories, equipment and experimental bench) for testing/characterisation of a material at cryogenic temperatures. (authors)
[en] After the Haiti quake of 2010 an initiative started to better understand shaking effects in the Dominican Republic after natural earthquakes, in particular in the city of Santiago de los Caballeros, the second city in the country as far as inhabitants and economic wealth are concerned. Santiago has suffered several devastating earthquakes; in 1562 the city was rebuilt on a new site (the current location) further south from the responsible fault. It is well known that damage caused by an earthquake occurs associated to a number of factors, ground acceleration is one of them and is usually considered as the key to explain most of the damage. Ground acceleration varies from one point to another depending mainly on: distance to the source of the rupture, soil properties and topography. Regarding the distance, the further from the source the less acceleration is expected due to distance attenuation. On the other hand, different soil properties and different topographies will produce different responses to the propagating wave. Within the range of a few kilometres, the effect of distance attenuation might be far less relevant than the effect of the varying properties of soils. This paper gathers together results obtained from the seismic hazard and microzonation studies developed in the city of Santiago: i) quantification of regional seismic hazard dominated by the Septentrional fault, ii) a new geological mapping of superficial formations, and iii) mapping of zones of homogeneous seismic response and liquefaction susceptibility.
[es]Tras el terremoto de Haití de 2010 dio comienzo una iniciativa para tratar de entender mejor los efectos de los terremotos en la República Dominicana, en particular en la ciudad de Santiago de los Caballeros, segunda más importante del país. Santiago ha sufrido varios terremotos devastadores, en 1562 la ciudad fue reconstruida en un nuevo sitio al sur de la falla responsable. El daño debido a un terremoto ocurre asociado a un conjunto de factores, entre ellos, la aceleración del suelo, que por lo general se señala como el principal o como la clave para explicar la mayor parte de los efectos. La aceleración del suelo varía dependiendo principalmente de la distancia al epicentro, de las propiedades del suelo y de la topografía. En cuanto a la distancia, es de esperar menor aceleración conforme aumenta la distancia al epicentro. De otra parte, suelos con diferentes características dan lugar a diferentes respuestas. Los efectos de la topografía aún no se comprenden bien. El efecto de la atenuación de la distancia en un radio de unos pocos kilómetros suele ser mucho menos relevante que el efecto de la variación en las propiedades de los suelos. Este artículo recoge los resultados obtenidos de los estudios de peligro sísmico y Microzonificación sísmica en la ciudad de Santiago de los Caballeros: i) cuantificación del peligro sísmico regional debido a la falla septentrional; ii) un nuevo mapa geológico y iii) la cartografía de zonas de respuesta sísmica homogénea y susceptibilidad a la licuefacción
[en] A new dilatometer for in-situ soil testing has been developed which uses a rigid piston to load the soil. The new dilatometer 'called the Newcastle Dilatometer (NDMT)' uses a Hall effect transducer and a magnet system to measure the penetration of the piston during loading of the soil. The pressure required to penetrate the piston is recorded using a pressure transducer. The two transducers together can produce applied pressure-displacement curves for obtaining soil parameters which can be more reliable than those obtained based on just one or two contact pressures values as in the Marchetti dilatometer. Since the NDMT allows more control during in-situ testing, the same was carried out employing two test procedures, 'the stress increment controlled' and 'the constant rate of stress' at a site consisting of firm to stiff clay. This paper presents a comparison of the data obtained from the two test procedures and the effect the test procedure has on the various soil properties, in general and the shear strength, in particular. (author)
[en] We have considered that N. P. O., cathartic(castor oil) enema, which had been commonly used, as methods of removal of intraluminal gas for preparation of abdominal roentgenologic study, are not complete. So we reached follow conclusion, using combination of D. M. P. S. and castor oil. In 20 patients of all observation objects, 80 patients, we used D. M. P. S. and castor oil, and were able to get scout film with good quality on over 85 percent. However, rest of films, 15 percent were never thought to be failure. We are anxious for investigation of new chemicals which are able to eliminate the intraluminal gas by liquefaction, in a similar way of which gas foaming agent make the gas by gasification