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排序方式: 共有190条查询结果,搜索用时 296 毫秒
111.
介绍了在济钢烧结厂 2× 90 m2烧结机实施的烧结厂监控系统 (SPSS) ,该系统由济钢和芬兰罗德洛基公司共同开发 ,控制范围涵盖了烧结生产的全过程 ,包括一级模型 6个 ,二级模型 5个。为配合该系统的使用 ,济钢烧结厂对工艺、检测仪表、计算机系统进行了相应的配套改造。项目于 2 0 0 3年 10月全部投入运行后 ,对稳定生产、提高烧结矿质量、降低工人劳动强度起到了重要作用。 相似文献
112.
Vaaraslahti K Ristimäki J Virtanen A Keskinen J Giechaskiel B Solla A 《Environmental science & technology》2006,40(15):4776-4781
The effect of a conventional oxidation catalyst and a novel particle oxidation catalyst (POC) on diesel particles is studied using identical methodology. Regulated particulate matter emission measurement is followed by analyzing soluble organic fraction. In addition, size distributions are measured using a partial flow sampling system with a thermodenuder as an option. A parallel ELPI-SMPS method is used to study the particle effective density and, further, the mass. Tests are conducted using a heavy duty diesel engine with a very low sulfur fuel. A decrease in particle mass was observed when using a catalyst. When using a conventional catalyst the decrease was attributed to the decrease of soluble organic fraction, while using POC the nonsoluble fraction was also found to decrease, by 8-38%. This observation is confirmed by particle number measurement, and POC was found to decrease the dry particle number concentration measured downstream of a thermodenuder by 13-28%. Further particle structure analysis indicated lower density values when using conventional catalyst or POC. The physical size of the particles was not changed noticeably over either catalyst--implying the soluble organic fraction was condensed onto the soot, filling the voids in the porous structure of soot agglomerates, when no catalyst is used. 相似文献
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Psammoma bodies in a human transitional meningioma were studied by scanning electron microscopy (SEM) of deparaffinized tissue slices and sections. The bodies, visible as round structures by light microscopy, were confirmed in SEM to have a spherical rather than tubular three-dimensional structure. They were distinctly demarcated from a surrounding cup-like wall of cells. Under high magnification, the undulating surface of the bodies was found to be covered by interwoven fibers. In cross-section the bodies had a lamellar internal structure. The lamellae consisted of a network of concentric strands and fibers with associated bead-like material. The structure of psammoma bodies seen in SEM speaks in favor of their genesis by calcification of concentrically deposited fibrillar extracellular material. 相似文献
115.
Nora Pap Eva Pongrácz Mari Jaakkola Tiina Tolonen Vesa Virtanen Auli Turkki Zsuzsanna Horváth-Hovorka Gyula Vatai Riitta L. Keiski 《Journal of food engineering》2010
Reverse osmosis process for the concentration of black currant juice was carried using AFC-99 tubular membrane at 30 °C and 45 bar. The contents of selected flavonols and anthocyanins were analyzed after centrifugation; enzyme treatment by Panzym Super E and by Rohapect berry followed by centrifugation; and ultrafiltration black currant juices and juice concentrates. The total soluble solid (TSS) content of the juices increased from the initial 17.6–17.9 °Brix to 24–24.8 °Brix in the case of the centrifuged juice in the concentration process. Similarly, it increased from 14.5–15.5 °Brix to 23.1–23.4 °Brix for the Panzym Super E treated juice, and from 16.1–16.9 °Brix to 22.5–23.1 °Brix for the Rohapect berry treated black currant juices. The ultrafiltered juice had the lowest initial TSS content between 14.1 and 14.9 °Brix and it increased to 22.1–23.1 °Brix. The average permeate fluxes during the concentration process were 7.3 L m−2 h−1 for the centrifuged juice, 11.9 L m−2 h−1 for the Panzym Super E treated juice, 9.2 and 13.1 L m−2 h−1 for the Rohapect berry treated and ultrafiltered juice, respectively. Analysis indicated that the enzymatic treatment resulted in the increase of anthocyanin and flavonol content of the juices. The centrifugation process decreased the amount of anthocyanins and flavonols to some extent. The juice clarified by ultrafiltration had significantly lower concentrations of anthocyanins and flavonols, while the juices treated by Panzym Super E had the highest levels of these flavonoids. This study recommends enzymatic pre-treatment by Panzym Super E, since it improves the permeate flux in reverse osmosis during the concentration process, and results in a juice concentrates highest in anthocyanins and flavonols. 相似文献
116.
Elovainio Marko; Kivim?ki Mika; Vahtera Jussi; Keltikangas-J?rvinen Liisa; Virtanen Marianna 《Canadian Metallurgical Quarterly》2003,22(3):287
The aim of this longitudinal cohort study was to investigate whether sleeping problems and health behaviors (smoking, alcohol consumption, and sedentary lifestyle) mediate the association between organizational justice and employee health. Health indicators were minor psychiatric morbidity, as assessed by the General Health Questionnaire (U. Werneke, D. P. Goldberg, 1. Yalcin, & B. T. Ustun, 2000), and poor self-rated health status. The results of logistic regression analysis of data for 416 male and 3,357 female hospital employees working during the 1998-2000 period in 10 Finnish hospitals suggest that sleeping problems are one of the underlying factors causing the adverse health effects of low organizational justice at work. No support for a mediating role of health behaviors between low organizational justice and health problems was obtained. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Teemu Valtonen Erkko Sointu Jari Kukkonen Kati Mkitalo Nhi Hoang Pivi Hkkinen Sanna Jrvel Piia Nykki Anne Virtanen Susanna Pntinen Emma Kostiainen Jo Tondeur 《Journal of Computer Assisted Learning》2019,35(4):491-502
The aim of this study is to outline the development and changes in pre‐service teachers' technological pedagogical content knowledge (TPACK) assessments during the first 3 years in teacher education. Specifically, research was conducted at three measurement points over a 3‐year teacher education period. The target group consisted of pre‐service teachers (N = 148) from three Finnish universities. Results indicate a growth in confidence related to all TPACK areas during the research period. The strongest gains were in pedagogical content knowledge. In addition, the gains were larger in other areas related to pedagogical knowledge than areas related to technology or content knowledge. In areas without pedagogical knowledge, the changes were more moderate. In the discussion section, recommendations are provided on the potential of longitudinal use of the TPACK model to study and improve the development of pre‐service teachers' TPACK. 相似文献
119.
AbstractThe sensitivity of NASA-TLX scale, modified Cooper–Harper (MCH) scale and the mean inter-beat interval (IBI) of successive heart beats, as measures of pilot mental workload (MWL), were evaluated in a flight training device (FTD). Operational F/A-18C pilots flew instrument approaches with varying task loads. Pilots’ performance, subjective MWL ratings and IBI were measured. Based on the pilots’ performance, three performance categories were formed; high-, medium- and low-performance. Values of the subjective rating scales and IBI were compared between categories. It was found that all measures were able to differentiate most task conditions and there was a strong, positive correlation between NASA-TLX and MCH scale. An explicit link between IBI, NASA-TLX, MCH and performance was demonstrated. While NASA-TLX, MCH and IBI have all been previously used to measure MWL, this study is the first one to investigate their association in a modern FTD, using a realistic flying mission and operational pilots.Practitioner summary: NASA-TLX scale, MCH scale and the IBI were evaluated in a flight training device. All measures were able to differentiate most task conditions and there was a positive correlation between NASA-TLX and MCH scale. An explicit link between IBI, NASA-TLX, MCH and performance was demonstrated.Abbreviations: ANOVA: Analysis of Variance; ECG: Electrocardiograph; F/A: fighter/attack; ft: feet; FTD: flight training device; G: Gravity; km: kilometer; m: meter; m/s: meters per second; MWL: mental workload; MCH: modified cooper-harper; NASA-TLX: NASA Task Load Index; NM: Nautical Mile; NN: normal-to-normal; IBI: inter-beat interval; ILS: Instrument Landing System; RR: R-Wave to R-Wave; SD: standard deviation; TTP: tactics, techniques and procedures; WTSAT: Weapon Tactics and Situation Awareness Trainer 相似文献
120.