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排序方式: 共有182条查询结果,搜索用时 15 毫秒
31.
Liyun Yang Ke Lu Mikael Forsman Kaj Lindecrantz Fernando Seoane Örjan Ekblom 《Ergonomics》2019,62(5):694-705
Work metabolism (WM) can be accurately estimated by oxygen consumption (VO2), which is commonly assessed by heart rate (HR) in field studies. However, the VO2–HR relationship is influenced by individual capacity and activity characteristics. The purpose of this study was to evaluate three models for estimating WM compared with indirect calorimetry, during simulated work activities. The techniques were: the HR-Flex model; HR branched model, combining HR with hip-worn accelerometers (ACC); and HR?+?arm-leg ACC model, combining HR with wrist- and thigh-worn ACC. Twelve participants performed five simulated work activities and three submaximal tests. The HR?+?arm-leg ACC model had the overall best performance with limits of agreement (LoA) of ?3.94 and 2.00?mL/min/kg, while the HR-Flex model had ?5.01 and 5.36?mL/min/kg and the branched model, ?6.71 and 1.52?mL/min/kg. In conclusion, the HR?+?arm-leg ACC model should, when feasible, be preferred in wearable systems for WM estimation.
Practitioner Summary: Work with high energy demand can impair employees’ health and life quality. Three models were evaluated for estimating work metabolism during simulated tasks. The model combining heart rate, wrist- and thigh-worn accelerometers showed the best accuracy. This is, when feasible, suggested for wearable systems to assess work metabolism. 相似文献
32.
Kimmo Nurmi Vladimir Ossipov Erkki Haukioja Kalevi Pihlaja 《Journal of chemical ecology》1996,22(11):2023-2040
We studied seasonal and between-tree variation in the composition and content of total and individual low-molecular-weight phenolics (LMWP) in leaves of mountain birch trees (Betula pubescens ssp.tortuosa). The major phenolic compounds were chlorogenic acid, quercetin-3-O--D-glucuronopyranoside, myricetin-3-O-(5-acetyl)-L-rhamnopyranoside, and 1-O-galloyl--D-(2-O-acetyl)-glucopyranose. The content of total phenolics, as well as the sum of individual LMWP, varied only slightly among trees while variation in contents of individual LMWP was large. Concentrations of almost all phenolics decreased during the growing season but pairwise correlations between individual phenolics remained similar over the whole season indicating tree-specific LMWP profiles over the season. Among flavonoids, the between-tree component of variation was 2.6 times as large as the seasonal component, while for variation of nonflavonoids the between-tree component was larger than the seasonal one. To explain the significant correlations within both flavonoid and nonflavonoid compounds, we discuss the biogenesis of LMWP in birch leaves, as well as their ecological role. 相似文献
33.
Underground space in land-use planning 总被引:3,自引:0,他引:3
Kimmo Rnk Jouko Ritola Kari Rauhala 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》1998,13(1):39
In 1988, the Finnish Ministry of the Environment appointed a committee to review existing planning systems for underground construction. In its report in spring 1990, the committee concluded that current legislation and planning procedures were unsatisfactory. In response, a study on “Underground Space in the Planning and Land Use” was launched in June 1994, and was completed in summer 1996. The study formed part of Finland's Rock Engineering 2000 programme. The study reviewed the present situation in underground planning; examined current uses of underground facilities; created a basic method for the classifying the building potential of rock areas, identified the various methods currently available for assessing the environmental impacts of underground construction on the basis of the legislation in force (EIA); to developed methods for assessing the costs to the urban community of underground space, particularly in comparison with equivalent costs of space aboveground; and drafted a proposal concerning planning of different level and permit procedures for underground space. This paper discusses each aspect of the study. 相似文献
34.
Mäkelä E Mäkelä EA Partio EK Juutilainen T Lähteenkorva K Törmälä P Rokkanen P 《Journal of materials science. Materials in medicine》2008,19(3):1061-1067
Self-reinforced polylactide–polyglycolide (80/20) composite rods, 2 mm in diameter and 36 mm in length, were implanted into
the dorsal subcutaneous tissue of 20 rabbits. Osteotomies of the distal femur were fixed with these rods (2 × 15 mm) in the
rabbits. The follow-up times varied from 3 to 104 weeks. After sacrifice, three-point bending and shear tests and molecular
weight measurements were performed for subcutaneously placed rods. Radiological, histological, microradiographic, oxytetracycline-fluorescence,
and histomorphometrical studies of the osteotomized and intact control femora were performed. After 6 weeks the mechanical
properties had decreased significantly, but osteotomies had healed uneventfully. The present investigation showed that the
mechanical strength and fixation properties of SR-Polylactide–glycolide (80/20) rods are suitable for fixation of cancellous
bone osteotomies in rabbits provided that the operative technique is correct. The present article is the first report on the
application of these rods for fixation of cancellous bone osteotomies. 相似文献
35.
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
36.
37.
Kokkonen K Meltaus J Pensala T Kaivola M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(3):557-559
Acoustic wave fields in a thin-film bulk acoustic wave resonator are studied using a heterodyne laser interferometer. The measurement area is extended outside the active electrode region of the resonator, so that wave fields in both the active and surrounding regions can be characterized. At frequencies at which the region surrounding the resonator does not support laterally propagating acoustic waves, the analysis of the measurement data shows exponentially decaying amplitude fields outside the active resonator area, as suggested by theory. The magnitude of the imaginary wave vectors is determined by fitting an exponential function to the measured amplitude data, and thereby the experimentally determined dispersion diagram is extended into the region of imaginary wave numbers. 相似文献
38.
Kimmo Lahtinen Petri Johansson Tommi Kääriäinen David C. Cameron 《Polymer Engineering and Science》2012,52(9):1985-1990
Adhesion of extrusion‐coated polymer sealing layers on an atomic layer deposited (ALD) aluminum oxide (Al2O3) surface coating was investigated with a view to gain information on the applicability of ALD deposited barrier layers in fiber‐based packaging materials. The polymers used for the sealing layer were low density polyethylene (LDPE), polyethylene terephthalate (PET), and polylactide (PLA). They were extrusion‐coated onto the ceramic side of paper/PET/Al2O3 substrates, where the Al2O3 layer was a few tens of nanometers thick. According to the results, good adhesion was obtained for LDPE coating, whereas the other coatings showed a considerable lack of adhesion. Presumably, the oxidation faced by LDPE in the air gap of the extrusion‐coating process was able to create an extensive number of reactive sites that strongly bonded with the hydroxyl groups on the oxide surface of the substrate. With the PET and PLA coatings, such oxidation did not occur and the adhesion obtained remained at a relatively poor level. With all of the coatings, the adhesion levels were improved using corona discharge equipment as a pretreatment prior to the extrusion‐coating process. POLYM. ENG. SCI., 52:1985–1990, 2012. © 2012 Society of Plastics Engineers 相似文献
39.
An effective wet digestion procedure for the determination of total iodine contents in milk powder samples was developed utilizing a high-pressure asher technique. The optimized method based on a two-stage digestion procedure. In the first stage, 500 mg samples were digested at 300 °C for 2 h using 15.2 mol L?1 HNO3 (5 mL) and 30 % H2O2 (3 mL). After the first digestion stage, digestion vessels were allowed to cool down and 1.2 mL of 20 % (w/v) Na2S2O8 solution was added as an additional oxidizing agent to the samples. After that, the vessels were closed, and they were heated at 100 °C for 30 min, resulting in clear and colorless sample solutions. Iodine concentrations in the digested samples were measured with inductively coupled plasma mass spectrometry. The accuracy of the optimized method was confirmed by analyzing milk powder reference material (BCR-151, milk powder). The obtained value for iodine (5.29?±?0.37 mg kg?1, n?=?6) was in good agreement with the certified value (5.35?±?0.14 mg kg?1). Furthermore, the results obtained for reference material showed that the developed method can be applied also for the determination of other elements, e.g., copper, iron, and lead in the digested milk powder samples. 相似文献
40.
Kimmo Lahtinen Philipp MaydannikPetri Johansson Tommi KääriäinenDavid C. Cameron Jurkka Kuusipalo 《Surface & coatings technology》2011,205(15):3916-3922
The feasibility of a novel continuous atomic layer deposition process in improving the barrier properties of extrusion-coated papers was investigated. The polymer coatings on paper were low-density polyethylene, polypropylene, polyethylene terephtalate and polylactide. The new method was tested by depositing 100 nm aluminium oxide layers on the polymer side of the structures. According to test results, the aluminium oxide layer produced significant barrier improvements. The water vapour and oxygen transmission rates measured were approximately 3-5 times lower than those of the untreated samples. Even better improvements were found for the water vapour transmission rates of polyethylene terephtalate and polylactide coated papers being over 10 times lower than for the untreated structures. It is proposed that the better water vapour barrier improvements were found because of these polymers' disposition to water sorption in the non-processed samples. The continuous atomic layer deposition process caused also considerable changes in the topography and morphology of some polymers, which reduced the barrier properties and applicability of the structures. Further research is needed to enable the use of lower process temperatures in the continuous atomic layer deposition process, which would improve the feasibility of the new method. 相似文献