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1.
The objective of this work is to calculate the pressures, stresses, and strains induced into moist concrete during freezing and thawing. The applied theory is based on thermodynamics and the linear theory of elasticity. If no additional salts are dissolved in the pore water the inputs needed in the theory are relative humidity and temperature measured in the sample chamber and inside concrete and evaporable water amount in the pore structure. Theoretical results were compared with the test results made with two concretes cured under water or at 96% relative humidity. One of the concretes was air entrained and in the comparison concrete no air-entraining agents were used. In the test cylinders cured under water the largest tensional stresses in freezing occurred on the surface of the test cylinders both in the axial and tangential direction. The largest tensional stress was 2.2 MPa, both in air-entrained and in non air-entrained concretes. The largest tensional stresses in the warming phase took place at the end of the thawing period when the chamber temperature was around +5 °C. Then the maximum tension occurred in the middle of the concrete cylinder in the axial direction of the cylinder. This maximum tensional stress was over 2.5 MPa in the air-entrained concrete cured in the relative humidity of 96%. The thermodynamic pumping effect at the end of the thawing phase in every cycle can increase the pore water amount remarkably if free water or moisture is available on the surface of the structure or in the environment vapor. The thermodynamic pumping effect seems to be remarkably greater and more dangerous in air-entrained concretes. 相似文献
2.
This paper describes a validation study performed by comparing the Climate-SAF Surface Albedo Product (SAL) to ground truth observations over Greenland and the ice-covered Arctic Ocean. We compare Advanced Very High Resolution Radiometer (AVHRR)-based albedo retrievals to data from the Greenland Climate Network (GCN) weather stations and the floating ice station Tara for polar summer 2007. The AVHRR dataset consists of 2755 overpasses. The overpasses are matched to in situ observations spatially and temporally. The SAL algorithm presented here derives the surface broadband albedo from AVHRR channels 1 and 2 using an atmospheric correction, temporal sampling of an empirical Bidirectional Reflectance Distribution Function (BRDF), and a narrow-to-broadband conversion algorithm. The satellite product contains algorithms for snow, sea ice, vegetation, bare soil, and water albedo. At the Summit and DYE-2 stations on the Greenland ice sheet, instantaneous SAL RMSE is 0.073. The heterogeneous surface conditions at satellite pixel scale over the stations near the Greenland west coast increase RMSE to > 0.12. Over Tara, the instantaneous SAL RMSE is 0.069. The BRDF sampling approach reduces RMSE over the ice sheet to 0.053, and to 0.045 over Tara. Taking into account various sources of uncertainty for both satellite retrievals and in situ observations, we conclude that SAL agrees with in situ observations within their limits of accuracy and spatial representativeness. 相似文献
3.
Vesa Halava Tero Harju Tomi Kärki Patrice Séébold 《Theoretical computer science》2009,410(8-10):943-948
We prove that there exist infinitely many infinite overlap-free binary partial words containing at least one hole. Moreover, we show that these words cannot contain more than one hole and the only hole must occur either in the first or in the second position. We define that a partial word is -overlap-free if it does not contain a factor of the form where the length of is at least . We prove that there exist infinitely many 2-overlap-free binary partial words containing an infinite number of holes. 相似文献
4.
Vesa Halava Tero Harju Juhani Karhumki Michel Latteux 《Theoretical computer science》2007,380(3):355-362
In the Post Correspondence Problem (PCP) an instance (h,g) consists of two morphisms h and g, and the problem is to determine whether or not there exists a nonempty word w such that h(w)=g(w). Here we prove that the PCP is decidable for instances with unique blocks using the decidability of the marked PCP. Also, we show that it is decidable whether an instance satisfying the uniqueness condition for continuations has an infinite solution. These results establish a new and larger class of decidable instances of the PCP, including the class of marked instances. 相似文献
5.
Jouni Isoaho Vesa Köppä Jarkko Oksala Pasi OjalaAuthor vitae 《Microprocessors and Microsystems》1997,20(10):2330-615
The BOAR emulation system is targeted to hardware/software (HW/SW) codevelopment of advanced embedded DSP and telecom systems. The challenge of the BOAR system is efficient customization of programmable hardware, and dedicated partitioning routine to target applications and structures, which allows quite high overall system performance. The system allows multiple configurations for communication between processors and field programmable gate arrays (FPGAs) making the BOAR system an efficient tool for real-time HW/SW coverification. The reprogrammable hardware of the emulation tool is based on four Xilinx 4000-series devices, two Texas TMS320C50 signal processors and one Motorola MC68302 microcontroller. With current devices the BOAR hardware provides approximately 40–70 kgates of logic capacity in DSP applications. The emulation capacity can be expanded by connecting several similar boards in chain. The system has also a versatile internal reprogrammable test environment for test bench development, performance evaluations and design debugging. The logic development environment is based on the Synopsys synthesis tools and an automatic design management software, which performs resource mapping and performance-driven design partitioning between FPGAs. The emulation hardware is currently connected to logic and software development environments via an RS-232C bus. The BOAR emulation system has been found a very efficient platform for real-life prototyping of different types of DSP algorithms and systems, and validating correct functionality of a VHDL macro library. 相似文献
6.
Damiana-Maria Vulturar Maria Adriana Neag tefan Cristian Vesa Anca-Diana Maierean Diana Gherman Anca Dana Buzoianu Olga Hilda Orsan Doina-Adina Todea 《International journal of molecular sciences》2022,23(22)
The infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) generated many challenges to find an effective drug combination for hospitalized patients with severe forms of coronavirus disease 2019 (COVID-19) pneumonia. We conducted a retrospective cohort study, including 182 patients with severe COVID-19 pneumonia hospitalized between March and October 2021 in a Pneumology Hospital from Cluj-Napoca, Romania. Among patients treated with standard of care, 100 patients received remdesivir (R group) and 82 patients received the combination of remdesivir plus tocilizumab (RT group). We compared the clinical outcomes, the inflammatory markers, superinfections, oxygen requirement, intensive care unit (ICU) admission and mortality rate before drug administration and 7 days after in R group and RT group. Borg score and oxygen support showed an improvement in the R group (p < 0.005). Neutrophiles, C-reactive protein (CRP) and serum ferritin levels decreased significantly in RT group but with a higher rate of superinfection in this group. ICU admission and death did not differ significantly between groups. The combination of remdesivir plus tocilizumab led to a significantly improvement in the inflammatory markers and a decrease in the oxygen requirement. Although the superinfection rate was higher in RT group than in R group, no significant difference was found in the ICU admission and mortality rate between the groups. 相似文献
7.
Raine Mäntysalo Johanna Tuomisaari Kaisa Granqvist Vesa Kanninen 《Planning Theory & Practice》2013,14(4):555-572
ABSTRACTThe city of Lahti, Finland, has developed a unique policy of combining city strategy work with strategic master planning in an iterative process. It thereby offers insights to research on strategic spatial planning, exemplifying how institutional frameworks of statutory planning can be utilized as resources in strategic planning. Three lessons from the Lahti case are drawn: (1) utilize the moments of opportunity in the institutional environment of statutory planning, (2) shift the focus from the level of ‘strategic plans’ to the policy level of strategy work, (3) develop strategic planning as a platform for diverse ‘languages’. 相似文献
8.
The value and volumes of industrial stump fuel supply are increasing for energy production. Accurate estimates of aboveground and belowground biomass of trees are important when estimating the potential of stumps as a bioenergy source. In this study two stump biomass equations were adapted and tested using them as calibrated stump biomass models computed as the cumulative sum by a local stand. In addition, variables derived from stem measurements of the forest harvester data were examined to predict stump biomass of a stand by applying regression analysis. The true stump yield (dry weight) was used as the reference data in the study. Both biomass models performed well (adjusted R2 ˜ 0.84) and no advance was found in using other stem dimensions as independent variables in the model. The stand-level model can be used in innovative stump biomass prediction tools for increasing efficiency of energy wood procurement planning to stands within a certain area. In practice, wood procurement managers would need to adapt developed system and decide whether the degree of accuracy/precision provided by the models is acceptable in their local stand harvesting conditions. 相似文献
9.
C Llado Carbonell O Arango Toro J Vesa Llanes O Bielsa Gali A Gelabert Mas 《Canadian Metallurgical Quarterly》1996,6(2):292-296
Initially thought to act as tissue replacement, cultured epithelial allografts are now known to work by providing a potent stimulus for healing. In a similar fashion, we believe that traditional autografts may also provide a stimulus to help heal chronic wounds, thus acting as pharmacological agents for healing. We attempted to assess the possibility of augmenting the stimulatory properties of donor skin by initiating the healing process in the donor region prior to grafting. This was accomplished by pre-wounding the donor area 3 days prior to harvesting the donor skin. We compared these 'pre-wounded' grafts to those harvested immediately. Two patients underwent punch grafting for chronic leg ulceration. Half of the ulcer was grafted with donor skin harvested from an area that was pre-wounded and the other half from freshly harvested skin. We evaluated each for improvement of granulation tissue and degree of edge effect (migration of the previously dormant wound edges). All the grafts did well. There was marked improvement in granulation tissue in the ulcer bed after grafting, and the obvious presence of an edge effect. The edge effect was increased on the site where the pre-wounded grafts were placed. It may be possible to augment the growth stimulatory properties of donor skin. This may offer therapeutic options in patients with chronic wounds. 相似文献
10.
We consider equality sets of prefix morphisms, that is, sets E(g1,g2)={w|g1(w)=g2(w)}, where g1 and g2 are prefix morphisms. Recall that a morphism g is prefix if, for all different letters a and b, g(a) is not a prefix of g(b). We prove a rather surprising equality on families of languages, namely, that the family of regular star languages coincides with the family of languages of form πA(E(g1,g2)) for some prefix morphisms g1 and g2, and a projection πA which deletes the letters not in A. 相似文献