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排序方式: 共有555条查询结果,搜索用时 31 毫秒
1.
Antti Voss Niko Hänninen Mohammad Pour-Ghaz Marko Vauhkonen Aku Seppänen 《Materials and Structures》2018,51(3):68
The development of visualizing tools to monitor unsaturated moisture flow in cement-based materials is of great importance, as most degradation processes in cement-based materials are connected to and take place in the presence moisture. This paper investigates the ability of electrical capacitance tomography (ECT) to image two-dimensional (2D) unsaturated moisture flow in cement-based materials. In ECT, the electrical permittivity distribution within an object is reconstructed based on measured capacitances between electrodes attached on the object’s surface. In a series of experiments, mortar specimens with and without discrete cracks were imaged with ECT during a 2D moisture ingress. The results show that ECT is able to monitor the evolution of the moisture flow, and to approximate the shape and position of the moisture front. These findings indicate that ECT is a viable method for monitoring and visualizing 2D unsaturated moisture flow in cement-based materials in the presence and absence of discrete cracks. 相似文献
2.
During the process of writing a comprehensive dictionary ofFinnish dialects, a large set of maps describing the regionaldistribution of the dialect words have been compiled in electronicform. In this article, we set out to analyse this corpus ofdata in order to gain new insight on the variation of Finnishdialects. We use a wide range of multivariate data analysismethods, including principal components analysis, independentcomponents analysis, clustering, and multidimensional scaling.We explain how to preprocess the data to overcome the problemof uneven sampling caused by the way the data has been collected.We discuss the results obtained by these methods and comparethem to the traditional view of Finnish dialect groups. 相似文献
3.
S Mattila L Heikkil? J Sipponen K Verkkala K Ky?sola T Mattila A J?rvinen R Luosto L Heikkinen P Ketonen J Salo A Nemlander I Mattila MS Nieminen 《Canadian Metallurgical Quarterly》1997,86(2):113-120
BACKGROUND: Clearance of large molecules from the interstitial space is an important function of lymphatics and is affected by local pathologic changes. OBJECTIVE: To determine if the clearance rate of interstitially injected albumin is correlated to tumour characteristics and outcome in women with invasive breast cancer. METHOD: In a consecutive series of women coming to biopsy for suspected breast cancer, technetium-tagged albumin was injected into the tissue adjacent to the palpable mass. The isotope disappearance rate was measured over two hours. Also assessed were the maximum vessel density (MVD-using Factor VIII polyclonal antisera), the proliferation rate (using Ki-67 antisera), node status, tumour size, histologic and nuclear grade, mitotic rate, and p53 and c-erbB-2 oncoproteins. All patients were followed until relapse and for a minimum of 10 years. RESULTS: In multivariate analysis, an association between relapse-free survival and isotope clearance rate was suggested (p = 0.024). The best outcome was seen in patients with the least isotope clearance. Node status, size, histologic and nuclear grade, and mitotic rate correlated with survival. MVD did not correlate with survival and was inversely related to the isotope clearance rate. Tumour proliferation rate, and the c-erbB-2 and p53 oncoproteins did not relate to outcome. CONCLUSION: The role of lymphatics in breast cancer is difficult to study. Measurement of interstitial clearance may be a useful technique and could be a prognostic factor. 相似文献
4.
Antti Hukka 《Drying Technology》1996,14(7):1719-1732
A mathematical model for simulation of softwood drying also in temperatures exceeding the boiling point of water is presented. The equations are formulated in a conservative form based on the classical volume averaging technique with an addition of a pressure-driven moisture flux in the boundary condition. Numerical results using the control volume method are presented to show that this term missing in existing simulation models may account far the calculated build up of moisture at the very surface of a wood board. The possibility of neglecting the air- phase in the calculation of total gaseous pressure is investigated by means of an example. It shows that the effect of air pressure is only of very litde importance in the case of transversal flow in moderate tempertures. 相似文献
5.
Antti Valmari 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(3):180-194
This article discusses observations made when the state space of the 2 × 2 × 2 Rubik’s cube was constructed with various programs
based on various data structures, gives theoretical explanations for the observations, and uses them to develop more memory-efficient
data structures. The cube has 3,674,160 reachable states. The fastest program runs in 20 s and uses 11.1 million bytes of
memory for the state set structure. It uses a 31-bit representation of the state and also stores the rotation through which
each state was first found. Its memory consumption is remarkably small, considering that 3,674,160 × 31 bits is about 14.2
million bytes. Getting below this number was made possible by sharing common parts of states. Obviously, it is not possible
to reduce memory consumption without limit. We derive an information-theoretic hard average lower bound of 6.07 million bytes
that applies in this setting. We introduce a general-purpose variant of the data structure and end up with 8.9 million bytes
and 48 s. We also discuss the performance of BDDs and perfect state packing in this application. 相似文献
6.
Janne Halme Minna Toivola Antti Tolvanen Peter Lund 《Solar Energy Materials & Solar Cells》2006,90(7-8):872-886
Electrochemical impedance spectroscopy was used to determine the effective charge transfer resistances of porous dye-sensitized solar cell counter electrodes prepared by low-temperature spray deposition and compression of conductive carbon and platinized Sb-doped SnO2 powders on indium tin oxide-coated plastic substrates. The charge transfer resistances were 0.5–2 and 8–13 Ω cm2, respectively, when using 3-methoxypropionitrile as the electrolyte solvent. The manufacturing method used lends itself to produce mechanically stable and even-quality electrodes in an easy and fast manner. 相似文献
7.
A microelectromechanical system (MEMS) sound waveguide is considered as a transmission line for RF signals. We analyze a device geometry of a straight one-dimensional microsize silicon rod, where a longitudinal acoustic wave is generated and detected using capacitive transducers. Linear, isotropic, and nondispersive acoustic-wave propagation is assumed. Based on the calculation of the electromechanical impedance, an electrical equivalent model is derived for the acoustic transmission line. A numerical example and a comparison to measured properties of a MEMS-transmission-line resonator shows that the characteristic impedance level of the waveguide is typically high, which causes challenges for matched termination. Solutions to overcome the matching problems are discussed. 相似文献
8.
A prospective clinical trial comparing adverse postmyelographic effects and myelographic quality of metrizamide and iohexol was conducted. Using a predetermined, randomized assignment, 24 horses exhibiting neurologic signs were administered either metrizamide (180 mgl/ml) or iohexol (180 mgl/ml) via cerebellomedullary puncture. Each horse was evaluated postmyelographically for adverse effects. Myelographic quality was assessed by a numerical scoring method. Adverse effects were observed more frequently with metrizamide (21) compared with iohexol (6) myelography (p < 0.05). Seizures, intensification of preexisting neurologic signs and prolonged anesthetic recovery were the most common complications after myelography. There was no difference in myelographic quality (p > 0.05). We conclude that iohexol is safer than metrizamide for equine myelography and that quality myelograms can be obtained with either contrast medium. 相似文献
9.
Antti Oulasvirta Tye Rattenbury Lingyi Ma Eeva Raita 《Personal and Ubiquitous Computing》2012,16(1):105-114
Examining several sources of data on smartphone use, this paper presents evidence for the popular conjecture that mobile devices
are “habit-forming.” The form of habits we identified is called a checking habit: brief, repetitive inspection of dynamic content quickly accessible on the device. We describe findings on kinds and frequencies
of checking behaviors in three studies. We found that checking habits occasionally spur users to do other things with the
device and may increase usage overall. Data from a controlled field experiment show that checking behaviors emerge and are
reinforced by informational “rewards” that are very quickly accessible. Qualitative data suggest that although repetitive
habitual use is frequent, it is experienced more as an annoyance than an addiction. We conclude that supporting habit-formation
is an opportunity for making smartphones more “personal” and “pervasive.” 相似文献
10.
Veronique Demers-Mathieu Ciera DaPra Gabrielle Mathijssen David A. Sela Kirsi M. Jrvinen Antti Seppo Shawn Fels Elena Medo 《International journal of molecular sciences》2021,22(4)
Background: Preexisting immunity to SARS-CoV-2 could be related to cross-reactive antibodies to common human-coronaviruses (HCoVs). This study aimed to evaluate whether human milk antibodies against to S1 and S2 subunits SARS-CoV-2 are cross-reactive to S1 and S2 subunits HCoV-OC43 and HCoV-229E in mothers with a confirmed COVID-19 PCR test, in mothers with previous viral symptoms during COVID-19 pandemic, and in unexposed mothers; Methods: The levels of secretory IgA (SIgA)/IgA, secretory IgM (SIgM)/IgM, and IgG specific to S1 and S2 SARS-CoV-2, and reactive to S1 + S2 HCoV-OC43, and HCoV-229E were measured in milk from 7 mothers with a confirmed COVID-19 PCR test, 20 mothers with viral symptoms, and unexposed mothers (6 Ctl1-2018 and 16 Ctl2-2018) using ELISA; Results: The S2 SARS-CoV-2 IgG levels were higher in the COVID-19 PCR (p = 0.014) and viral symptom (p = 0.040) groups than in the Ctl1-2018 group. We detected a higher number of positive correlations between the antigens and secretory antibodies in the COVID-19 PCR group than in the viral symptom and Ctl-2018 groups. S1 + S2 HCoV-OC43-reactive IgG was higher in the COVID-19 group than in the control group (p = 0.002) but did not differ for the other antibodies; Conclusions: Mothers with a confirmed COVID-19 PCR and mothers with previous viral symptoms had preexisting human milk antibodies against S2 subunit SARS-CoV-2. Human milk IgG were more specific to S2 subunit SARS-CoV-2 than other antibodies, whereas SIgA and SIgM were polyreactive and cross-reactive to S1 or S2 subunit SARS-CoV-2. 相似文献