Estimation of microwave parameters of crops from radiometric measurements

A simple approach is developed to calculate the microwave characteristics of a crop canopy. The approach is based on passive microwave measurements which are acquired for at least two levels of the vegetation, during the crop development. The method is applied to estimate the optical depth and the single scattering albedo of wheat fields at C-band, from two data sets. The results are analysed for several configurations of the measurement system in terms of polarization and view angle. Application of this simple approach appears to be very useful to investigate the effect of the vegetation structure on the canopy microwave emission.     

Mixture of ε-caprolactone-lactide copolymer and tricalcium phosphate: a histological and immunohistochemical study of tissue reactions

In cranio-maxillofacial surgery, bone transplantation is needed for treatment of bony defects. An autograft, allograft or biomaterial can be used. Autogenous bone grafts are considered to be the best materials available, but there are some disadvantages in their use including donorsite morbidity, need for a second operative site and limited graft supply. A search for new bone-graft materials therefore remains necessary. We prepared a mixture of tricalcium phosphate (TCP), which is a resorbable, non-toxic, osteoconductive ceramic material and -caprolactone-lactide copolymer P(-CL/DL-LA), a resorbable polymer, and placed it in the dermis and in mandibular bone defects in 13 rabbits. Follow-up times were two, three, seven, eight, 12, 15 and 18 weeks, tissue reactions were assessed, histologically and immunohistochemically. Times of resorption of the material from tissues were reported. We found that the mixture caused a mild inflammatory reaction when placed in bone and severe inflammation when placed in dermis. No highly fluorescent layer of tenascin or fibronectin was found surrounding the implant area. The mixture was excellent to handle and very easy to place into bone defects. The results are promising and have led us to continue development of the mixture. © 1999 Kluwer Academic Publishers     

Viscoplasticity of Steamed Wood

Plasticity of steamed Spruce wood, compressed in uniaxial strain, is addressed in terms of a classical linear viscoplasticity model. The dynamic stiffness modulus increases along with compressive stress in the radial material direction, but decreases as a function of stress in the longitudinal direction. The longitudinal viscoplastic retardation time is an order of magnitude smaller than the radial retardation time, the plastic strain rate at invariant normalized overstress thus being much higher in the longitudinal direction. In the longitudinal direction, the retardation time increases along with increased compressive stress. The viscoplastic retardation time is inversely proportional to the straining rate in both material directions. Consequently, within any particular schedule of normalized overstress, the accumulation of plastic strain along with the number of loading cycles is independent of straining rate.     

A General Water Protection Plan of Lake Onega in Russia

Lake Onega is the second largest lake in Europe after Lake Ladoga. This paper is a part of the project concerning a general plan of water protection, as expressed in the Water Framework Directive. The aim of this paper was to present an investigation of the status of Lake Onega and to present steady state and dynamic modelling approach in order to assess the impacts of different loading scenarios of water quality of Lake Onega. In the project more catchment and water quality models were used but in this paper these models were chosen. The presented steady state model was the mass balance model of Vollenweider and the dynamic model is the box-type model AQUATOX. While Lake Onega preserves a good status of water as a whole, the problems with pollution and eutrophication exist in Petrozavodsk and Kondopoga Bays where anthropogenic loading is more pronounced.     

Failure Mechanisms of Thermomechanically Loaded SnAgCu/Plastic Core Solder Ball Composite Joints in Low-Temperature Co-Fired Ceramic/Printed Wiring Board Assemblies

The thermal fatigue endurance of completely lead-free 95.5Sn4Ag0.7Cu/plastic core solder ball (PCSB) composite joint structures in low-temperature Co-fired ceramic/printed wiring board (LTCC/PWB) assemblies was investigated using thermal cycling tests over the temperature ranges of −40°C–125°C and 0°C–100°C. Two separate creep/fatigue failures initiated and propagated in the joints during the tests: (1) a crack along the intermetallic compound (IMC)/solder interface on the LTCC side of the joint, which formed at the high-temperature extremes; and (2) a crack in the solder near the LTCC solder land, which formed at the low-temperature extremes. Moreover, localized recrystallization was detected at the outer edge of the joints that were tested in the harsh (−40°C–125°C) test conditions. The failure mechanism was creep/fatigue-induced mixed intergranular and transgranular cracking in the recrystallized zone, but it was dominated by transgranular thermal fatigue failure beyond the recrystallized zone. The change in the failure mechanism increased the rate of crack growth. When the lower temperature extreme was raised from −40°C to 0°C, no recrystallized zone was detected and the failure was due to intergranular cracks. (Received ...; accepted ...)     

Effects of Drying Conditions on Water Sorption and Phase Transitions of Freeze-Dried Horseradish Roots

The water sorption isotherms for freeze-dried horseradish roots (Armoracia rusticana) were determined using the interval sorption technique, and the thermal behavior of dried and rehumidified products was analyzed using differential scanning calorimetry. The hygroscopicity of the dried material increased when the surface temperature during freeze-drying was increased from 20°C to 60°C. Both sorption and thermal data showed that drying at high surface temperatures affected the physical structure of the material, resulting in increased water adsorption, decreased glass transition temperature, and increased unfreezeable water content. Water sorption isotherms and thermal data can be used to determine the proper drying and storage conditions for horseradish roots.     

Reducing size distortions of parametric stationarity tests

The use of asymptotic critical values in stationarity tests against the alternative of a unit root process is known to lead to over-rejections in finite samples when the considered process is stationary but highly persistent. We claim that, in recent parametric tests, this is caused by estimation errors which result when the autoregressive parameters used to describe the short-run dynamics of the process are replaced by estimators. We suggest a modification that corrects for these errors. Simulation results show that the modified test works reasonably well when the persistence is moderate and there is no time trend in the model but it is less effective when the model contains a time trend. An empirical illustration with inflation rate data is provided.     

Larox Pressure Filters in Filtration and Washing of Non-Ferrous Minerals Concentrates and Metallurgical Slurries

Automatic pressure filter with horizontally positioned filtration chambers and one endless filter cloth was first introduced in the late 1960s. Actual product development and process adaptation was done during the 1970s. During the next decade this type of dewatering equipment established a firm position in a wide range of applications in mining, metallurgical, and chemical industries worldwide. More than 320 of these first generation LAROX PF filters are in operation in many types of dewatering applications. The maximum unit size has been 35 m². In many cases, particularly in mining applications, the size of one unit has not been enough. For large production capacities in mining and mineral processing LAROX introduced in 1992 the big PF filter with maximum filtering area up to 144 m², the second generation PF filter. The big 144 has 24 filter plates (filter chambers) and all mechanical operations are performed hydraulicaly. The normal size PF filters (below 38 m²) are also available with hydraulic operation devices. The second generation PF and big PF filters considerably increase the application range of this type of dewatering equipment.

There are many processes in the mining, mineral and metallurgical industries, where improved efficiency in the solid/liquid separation would help achieve significant savings in energy consumption, affluent treatment costs, capital cost by simplifying the process, operation costs and especially labor costs. In most cases the efficiency can be improved by replacing the existing solid/liquid separation process with pressure filtration.