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71.
Hannu Korhonen Jukka Laakkonen Juhani Hakala Reijo Lappalainen 《Machining Science and Technology》2013,17(4):593-610
Burnishing is a cold working process that can be used to improve surface finish and surface hardness of workpieces. Conventionally, diamond or hard metal burnishing tools are used. In the present work, a novel burnishing tool was created by depositing amorphous diamond coating (AD) on a stainless steel tip. This tool was used to improve the surface finish and surface hardness of Nitronic-50 HS stainless steel workpieces. Nitronic-50 HS is used in a wide range of applications in industry. The burnishing process was carried out at different burnishing parameters (force, revolution speed, feed and number of tool passes). Burnishing parameters had a significant effect on the finishing process and they had to be optimized to achieve the best results. Remarkable improvements in surface finish (70% decrease in roughness) and hardness (25% increase) could be achieved with this tool and process in the surface finishing of Nitronic-50 stainless steel workpieces. From the tribological point of view, the AD-coated tip performed slightly better than a corresponding tip modified from a commercial polycrystalline diamond tip. AD coating seems to be very suitable for use in mechanical surface finishing tools such as a burnishing tip. 相似文献
72.
Anaerobic on-site treatment of black water and dairy parlour wastewater in UASB-septic tanks at low temperatures 总被引:2,自引:0,他引:2
Anaerobic on-site treatment of synthetic black water (BW) and dairy parlour wastewater (DPWW) was studied in two-phased upflow anaerobic sludge blanket (UASB)-septic tanks at low temperatures (10-20 degrees C). At all temperatures, total chemical oxygen demand (COD(t)) removal was above 90% with BW and above 80% with DPWW and removal of total suspended solids (TSS) above 90% with both wastewaters. Moreover, dissolved COD (COD(dis)) removal was approx. 70% with both wastewaters indicating good biological activity of the sludges. With BW, a single-phased reactor was found sufficient for good COD removals, while with DPWW, a two-phased process was required. Temperature optimum of reactor sludges was still 35 degrees C after long (398d) operation. Most of the nutrients from BW were removed with TSS, while with DPWW nutrient removal was low. In conclusion, UASB-septic tank was found feasible for (pre)treatment of BW and DPWW at low temperatures. 相似文献
73.
Coarse-grained fill or drainage layers beneath heated slab-on-ground structures are warm and moist throughout the year. According to the in situ measurements, the relative humidity of the fill layer is high at RH ≈100%. High relative humidity of the fill layer is not a sign of an un-functional drainage or capillary break layer, but a natural boundary condition for a slab structure adjacent to the moist subsoil. Due to the favourable conditions, microbe growth is very common in fill layers. Fungal or bacterial growth, in general, was detected in 98% of the test specimens taken beneath the ground slabs of heated buildings. Indicator species, either fungal or bacterial, were detected in 79% of the specimens. Yet, no moisture damage related to the ground floors was ever detected or recorded in the test buildings. The high microbe concentration in the fill layer beneath ground slabs is not a sign of moisture damage, but a natural state of the moist and warm fill layer. 相似文献
74.
The aim of this study was to monitor and characterise internal leachate quality at a Finnish municipal solid waste landfill (Lahti, Kujala, in operation for approximately 50 years) to provide information about its horizontal and vertical variation as well as effects of leachate recirculation on leachate quality. The study area (approximately 4 h) of the landfill had 14 monitoring wells for leachate quality monitoring over a 2-year period. The leachate was monitored for COD, BOD, TKN, NH4–N, Cl, pH and electric conductivity. The results showed high horizontal and vertical variability in leachate quality between monitoring wells, indicating that age and properties of waste, local conditions (e.g., water table) and degradation and dilution processes have a marked effect on local leachate quality. The mean COD values (642–8037 mg/l) and mean BOD/COD ratios (0.08–0.17) from the different monitoring wells were typical of landfills in the methanogenic phase of degradation. The leachate in the monitoring wells was notably more concentrated than the leachate effluent used for leachate recirculation. In the landfill as a whole the effects of the leachate recirculation on leachate quality, although difficult to distinguish from those caused by other factors, appeared to be minor during the study period. 相似文献
75.
Karjalainen J Riekkinen O Töyräs J Kröger H Jurvelin J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2008,55(10):2191-2197
In osteoporosis, total bone mass decreases and the thickness of the cortical layer diminishes in the shafts of the long bones. In this study, a simple ultrasonic in vivo method for determining the thickness of the cortical bone layer was applied, and the suitability of two different signal analysis techniques, i.e., envelope and cepstral methods, for measuring cortical thickness was compared. The values of cortical thickness, as determined with both techniques, showed high linear correlations (r ges 0.95) with the thickness values obtained from in vitro measurements with a caliper or in vivo measurements by peripheral quantitative CT (pQCT). No systematic errors that could be related to the cortical thickness were found. The in vivo accuracy of the measurements was 6.6% and 7.0% for the envelope and cepstral methods, respectively. Further, the in vivo precision for the envelope and cepstral methods was 0.26 mm and 0.28 mm, respectively. Although the results are similar for both of the techniques, the simplicity of the envelope method makes it more attractive for clinical applications. In conclusion, a simple ultrasound measurement provides an accurate estimate of the cortical bone thickness. The techniques investigated may have clinical potential for osteoporosis screening and therefore warrant more extensive clinical investigations with healthy and osteoporotic individuals. 相似文献
76.
Jukka Tuhkuri 《International journal for numerical methods in engineering》1997,40(16):2995-3014
A two-dimensional boundary element method for analysis of closed or partially closed cracks under normal and frictional forces is developed. The single domain dual formulation is used. As a contact problem is non-linear due to the friction phenomena at the crack interface and also because of the boundary conditions which may change during the loading, it is formulated in an incremental and iterative fashion. The stress intensity factors are calculated with the J-integral method. Also crack growth is considered. Several benchmark cases have been analysed to verify the results given by the method. The stress intensity factors and crack paths calculated are similar to those given in the literature. © 1997 John Wiley & Sons, Ltd. 相似文献
77.
Timo Hmlinen Harri Klapuri Jukka Saarinen Kimmo Kaski 《Concurrency and Computation》1997,9(9):877-896
This paper presents two parallel realizations of sparse distributed memory (SDM) on a tree-shaped computer. The original model of SDM is introduced in terms of generalized computer memory and artificial neural networks (ANNs). For parallellization purposes, addressing, storage and retrieval operations are explained in detail. Some existing implementations in various computing platforms are considered before introducing the tree-shaped parallel computer, TUTNC (Tampere University of Technology Neural Computer). Two mappings are given, each utilizing parallelism with different granularities, and compared in terms of measured execution time, task partitioning and load balancing. Performance estimates are given for a larger system. The results show that SDM can be well parallelized in TUTNC. © 1997 John Wiley & Sons, Ltd. 相似文献
78.
Accurate data about accident costs motivate top managers to improve safety in production. The problem has been, however, to specify costs reliably and easily. This article presents the computer-aided module for calculating accident costs in the TATU-Safety Information System developed by the Finnish Institute of Occupational Health. The module computes the direct costs and company-controlled total costs of accidents. The calculation is based on the accident consequence tree (ACT) method. The software provides information about accident costs to motivate accident prevention. The authors explain the system design of the software and its use in cost calculation. © 1997 John Wiley & Sons, Inc. 相似文献
79.
We have studied how different catalysts and diols affect the properties of low-molecular-weight (Mw (GPC) < 49800 g/mol) lactic-acid-based telechelic prepolymers. The catalysts and diols were tested separately in our previous studies. In this study, we used the best previously tested diols and catalysts together in order to prepare different types of telechelic prepolymers (for example, crystalline or amorphous). All condensation polymerizations were carried out in the melt, using different diols and different catalysts. The prepolymers were characterized by differential scanning calorimetry, gel permeation chromatography, titrimetric methods, and 13C nuclear magnetic resonance (13C-NMR). According to NMR, the resulting polymers contained less than 1 mol % of lactic acid monomer and less than 5.1 mol % of lactide. Dibutyltindilaurate, like tin(II)octoate, produced quite good molecular weights, but the resulting prepolymers contained exceptionally high amounts of D-lactic acid structures, and, therefore, these prepolymers were totally amorphous. Antimony(III)oxide produced a high-molecular-weight prepolymer when the diol used was aliphatic. Like DBTL, Sb2O3 produced amorphous prepolymers, which contained a lower amount of D-lactic acid structures than DBTL prepolymers. 1,8-dihydroxyanthraquinone produced a different kind of chain structure with Ti(IV)bu and Ti(IV)iso because one prepolymer had high crystallinity, and the other showed only a slight crystallinity. Sulphuric acid produced a very high-molecular-weight prepolymer with aliphatic 2-ethyl-1,3-hexanediol; and with aromatic diols, it produced quite good molecular weights, except with 1,8-dihydroxyanthraquinone. High-molecular-weight prepolymers produced with H2SO4 also showed high crystallinity; and, according to 13C-NMR, they did not contain lactide and D-lactic acid structures. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1011–1016, 1998 相似文献
80.
This article concerns the functionalization of polypropylene (PP) with oxazoline functionality by melt free radical grafting along with a low degree of degradation of PP in a batch mixer. A low volatile oxazoline, ricinoloxazoline maleinate (OXA), was used as the monomer. The grafting yield of OXA ranged from about 0.5 phr up to 1.5 phr (grams per 100 grams of PP) when its initial concentration and that of the peroxide ranged from 1.5 to 6.0 phr and 0.1 to 0.7 phr, respectively. The corresponding conversion of OXA to grafted OXA ranged from about 15 to 50%. Addition of styrene (St) as the comonomer did not enhance the grafting yield of OXA but markedly reduced the PP degradation. Also, little homo-and/or copolymers of OXA and/or St were found in the grafting system. This agrees with our finding that OXA and St did not copolymerize easily. The potential of using an OXA modified PP (PP-g-OXA) as the compatibilizer precursor in PP/PBT blends was examined as well. The presence of PP-g-OXA reduced the particle size of the dispersed phase (PBT) along with improved cohesion between the PP and PBT phases. This is consistent with a model kinetic study, which showed that the reaction between oxazoline and carboxylic functionalities was very fast. © 1996 John Wiley & Sons, Inc. 相似文献