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Software has been developed for digital control of WDW series testing machine and the measurement of fracture toughness by modularized design. Development of the software makes use of multi-thread and serial communication techniques, which can accurately control the testing machine and measure the fracture toughness in real-time. Three-point bending specimens were used in the measurement. The software operates stably and reliably, expanding the function of WDW series testing machine. 相似文献
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1 Introduction Withtherapiddevelopmentofcomputertechnology,digitalcontrolsystemsarewidelyusedinengineeringandresearch.InsomedigitalcontroldevicessuchasaGermanmadeWDWtestingmachineequippedwiththeDOLIsystem,however,duetoproblemsinsoftwareupdatingandlocalization,thefunctionareinsufficient.Forexample,thesystemsoftwareislimitedtothemeasurementofconventionalmechanicalproperty,incapableofmeasuringfracturetoughnessKICofmaterials.Asfracturetoughnessofmaterialsisanimportantparameterformaterialsev… 相似文献
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ZHANG Chun-jie QIAN Rui-rui 《浙江大学学报(A卷英文版)》2007,8(12):2037-2040
In this paper, we shall prove that the Marcinkiewicz integral operator #n, when its kernel Ω satisfies the L^1-Dini condition, is bounded on the Triehel-Lizorkin spaces. It is well known that the Triehel-Lizorkin spaces are generalizations of many familiar spaces such as the Lehesgue spaces and the Soholev spaces. Therefore, our result extends many known theorems on the Marcinkiewicz integral operator. Our method is to regard the Marcinkiewicz integral operator as a vector valued singular integral. We also use another characterization of the Triehel-Lizorkin space which makes our approach more clear. 相似文献
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Supersaturated solid solutions Fe1-xCx （0≤x≤0.9 ） of wide composition range have been prepared by mechanical alloying process. Nanocrystalline phase was formed for 0 ≤ x ≤ 0.67 and a large grain phase for 0.75 ≤ x ≤ 0.9. The large fraction of graphite volume puts off formation of nanocrystalline phase for high carbon content. In the large grain phase, magnetization follows simple magnetic dilution, and eoereivity He is mainly due to dissolution of carbon at grain boundaries. In the nanocrystalline phase the alloying effect of carbon is revealed by a distinct reduction of average magnetic moment. The increasing lattice constant with increasing carbon content is observed for x ≤ 0.5, suggesting that the high carbon concentration may enhance diffusion of carbon into the Fe lattice. It shows a discontinuity in the Hc variation with a grain size D of nanocrystalline phase. For small grain D below the critical value, Hc increases with D. For a large grain D, Hc decreases with increasing D. The solubility limit of carbon in a-Fe extended by nanocry- stalline phase formation is discussed. 相似文献
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Ｉｎ 1935 ,Ｐ .Ｅｒｄ¨ｏｓａｎｄＧＳｚｅｋｅｒｅｓｏｂｔａｉｎｅｄｔｈｅｃｌａｓｓｉｃａｌｉｎｅｑｕａｌｉｔｙＲ (ｍ ,ｎ)≤Ｒ (ｍ - 1,ｎ) Ｒ(ｍ ,ｎ - 1) . Ｉｎ 196 8,Ｋ .ＷａｌｋｅｒｐｒｏｖｅｄｔｈａｔＲ(ｎ ,ｎ)≤ 4Ｒ(ｎ- 2 ,ｎ) 2 . Ｉｎ 1998,ＨｕａｎｇＹ .Ｒ .ａｎｄＺｈａｎｇＫ .Ｍ .[1,2 ] ｐｒｏｖｅｄｔｈａｔＲ(ｍ ,ｎ)≤ 12 (β 3γ 5 ) 12 γ(4α 2 β - 3γ 6 ) (β 1) 2 Ｉｎｔｈｉｓｐａｐｅｒ ,ｗｅｏｂｔａｉｎｓｏｍｅｎｅｗｕｐｐｅｒｂｏｕｎｄｓｆｏｒＲ(ｍ ,ｎ ,ｌ)ａｎｄＲ(ｍ … 相似文献
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ZHAO Li-li 《浙江大学学报(A卷英文版)》2007,8(6):957-962
In this paper, we consider some polynomial (α,β)-metrics, and discuss the sufficient and necessary conditions for a Finsler metric in the form F=α a1β a2β2/α a4β4/α3 to be projectively flat, where ai (i=1,2,4) are constants with a1≠0, α is a Riemannian metric and β is a 1-form. By analyzing the geodesic coefficients and the divisibility of certain polynomials, we obtain that there are only five projectively flat cases for metrics of this type. This gives a classification for such kind of Finsler metrics. 相似文献
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The nonlinear Riemann problems were converted into nonlinear singular integral equations and the existence of the solution for the problem was proved by means of contract principle. 相似文献
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Andrea English 《Zeitschrift für Erziehungswissenschaft》2005,8(1):28-37
Zusammenfassung
Negativit?t und das Neue in John Deweys Theorie vom Lernen und der Demokratie — Für einen erneuten Blick auf Lernkulturen
Die Rolle des Neuen in Lernprozessen bezieht sich auf die grundlegende Frage, wie Lernen überhaupt m?glich ist und wo es beginnt.
In diesem Beitrag wird zun?chst John Deweys Lernkonzeption als Basis für die Analyse entwickelt. Dann wird die Beziehung zwischen
Negativit?t und dem Neuen erarbeitet. Beim übergang vom Alten zum Neuen und vom Gewussten zum Ungewussten entstehen Verwirrungen
und Schwierigkeiten, die in diesem Papier als Negativit?t im Lernprozess untersucht werden. Au?erdem vermittelt der Beitrag
Einsichten in praktische p?dagogische Probleme, etwa bezüglich der Frage, wie Lehrer und andere Erzieher Lernprozesse f?rdern
und wie Lernkulturen als besondere Lernumwelten Lehr-Lern-Prozesse unterstützen k?nnen.
Negativity and the new in John Dewey’s theory of learning and democracy Toward a renewed look at learning cultures
Summary The role of the New in learning processes relates to basic questions of how learning is possible, and where learning begins. Using John Dewey’s concept of learning as the basis for analysis, this inquiry looks into the relation between Negativity and the New and seeks to uncover the negativity in learning processes associated with the perplexities and difficulties which arise in the transitions from Old to New and Known to Unknown. Furthermore, it offers insight into practical pedagogical issues, such as how teachers and educators can support learning processes and how learning cultures, as particular environments for learning, can assist processes of teaching and learning.相似文献
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Study of the SISO mixedH
2/l1 problem for discrete time systems showed that there exists a unique optimal solution which can be approximated within any
prescribed missing error bound inl
2 norm with solvable suboptimal solutions and solvable superoptimal solutions.
Project supported by the National Natural Science Foundation of China (No. 60174026) and the Scientific Research Foundation
for Returned Overseas Chinese Scholars of Zhejiang Province (No. J20020546) 相似文献
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