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101.
Dr. Evert A. Dijksman 《Forschung im Ingenieurwesen》1987,53(6):169-184
Zusammenfassung Die vorliegende Abhandlung untersucht symmetrische ∇-f?rmige und 8-f?rmige Koppelkurven, die wenigstens zwei Wendepunkte enthalten.
Dabei werden auch die Sonderf?lle berücksichtigt. Au?er Hinweisen auf konstruktive Ma?nahmen finden sich ausführliche Berechnungsanleitungen
für die Gelenkvierecke, die solche Kurven erzeugen. Als besonders praktische erweist es sich, da? man in allen F?llen mit
zwei voneinander unabh?ngigen Parametern auskommt, welche auch die natürlichen Vorgaben für eine solche Konstruktion sind.
Es handelt sich hierbei zum einen um den Winkel 2τ, der von den beiden n?herungsweise geraden Bahnabschnitten eingeschlossen
wird, zum anderen um α0/π, den auf einen ganzen Zyklus bezogenen Kurbelwinkel zwischen den zwei symmetrisch zueinander, liegenden Wendepunktslagen.
Die besten (d.h. die übertragungsgünstigsten) Gelenkvierecke mit ∇-und 8-f?rmigen Koppelkurven k?nnen aus Diagrammen entnommen
werden. Zus?tzlich erleichtern Tabellen das Auffinden besonders guter Geradführungen. Mit diesen Hilfsmitteln ist es für den
Konstrukteur einfach geworden, ein seinen Anforderungen genügendes Getriebe auszuw?hlen. Die vorgestellten Getriebe sind u.a.
sehr gut zum Antrieb eines Malteserkreuzes geeignet. Weitere Anwendungen findet man in der Richtlinie VDI 2728.
Herrn It.A.T.J.M. Smals, Dozent für Automatisierung der Fertigung an der Fakult?t des Maschinenwesens der Technische Universit?t Eindhoven, Niederlande,
ist der Autor sehr verbunden für das von ihm weiterentwickelte Computerprogramm, dessen Ergebnisse in diesem Aufsatz benutzt
worden sind. Herrn Dipl.-Math.P. Tolle, im Fachgebiet Maschinenelemente und Getriebetechnik der Universit?t der Bundeswehr Hamburg, Bundesrepublik Deutschland,
dankt der Autor für die von ihm vorgeschlagenen Verbesserungen des Textes der vorliegenden Abhandlung. Schlie?lich dankt der
Autor seiner Ehefrau,M. Dijksman-Margarit, für die sch?nen Ausarbeitungen der Zeichnungen. 相似文献
102.
Rakovan J Reeder RJ Elzinga EJ Cherniak DJ Tait CD Morriss DE 《Environmental science & technology》2002,36(14):3114-3117
X-ray absorption spectroscopy was used to determine the local structure of U(VI) within synthetic fluorapatite at a concentration of 2.3 wt %. Extended X-ray absorption fine structure indicates that U(VI) substitutes into the Ca1 site. To accommodate this substitution the apatite structure significantly distorts such that the Ca1 site approximates octahedral coordination, with six uniform U-0 distances of 2.06A. An X-ray adsorption edge structure, with two inflection points, and optical emission spectra are consistent with 6d orbital crystal field splitting. These results indicate that significant amounts of U(VI) can be accommodated in the apatite structure but with an unexpected coordination, which may bear on the ultimate development of apatite-hosted nuclear-waste forms. 相似文献
103.
The effectiveness of prophylactic vitamin administration to schoolchildren in the Arctic region was evaluated in the biochemical investigation of schoolchildren by the assay of vitamins C, A, E, B1, B2, B6, B12 and folic acid in their blood serum before and after "Undevitum" intake. Deficiency of a number of vitamins was detected. It was shown that regular consumption of multivitamin "Undevitum" produced a positive effect on the parameters of their physical activity, the highest effect was observed in children with the normotensive reaction to loading, and it was less expressed in those with pathological hemodynamic reactions to the loading. 相似文献
104.
105.
Frits K. van Evert Joost Samsom Gerrit Polder Marcel Vijn Hendrik‐Jan van Dooren Arjan Lamaker Gerie W.A.M. van der Heijden Corné Kempenaar Ton van der Zalm Lambertus A.P. Lotz 《野外机器人技术杂志》2011,28(2):264-277
Broad‐leaved dock is a common and troublesome grassland weed with a wide geographic distribution. In conventional farming the weed is normally controlled by using a selective herbicide, but in organic farming manual removal is the best option to control this weed. The objective of our work was to develop a robot that can navigate a pasture, detect broad‐leaved dock, and remove any weeds found. A prototype robot was constructed that navigates by following a predefined path using centimeter‐precision global positioning system (GPS). Broad‐leaved dock is detected using a camera and image processing. Once detected, weeds are destroyed by a cutting device. Tests of aspects of the system showed that path following accuracy is adequate but could be improved through tuning of the controller or adoption of a dynamic vehicle model, that the success rate of weed detection is highest when the grass is short and when the broad‐leaved dock plants are in rosette form, and that 75% of weeds removed did not grow back. An on‐farm field test of the complete system resulted in detection of 124 weeds of 134 encountered (93%), while a weed removal action was performed eight times without a weed being present. Effective weed control is considered to be achieved when the center of the weeder is positioned within 0.1 m of the taproot of the weed—this occurred in 73% of the cases. We conclude that the robot is an effective instrument to detect and control broad‐leaved dock under the conditions encountered on a commercial farm. © 2010 Wiley Periodicals, Inc. 相似文献
106.
Throughout Europe, policy-makers recognize the development potentials of regions in which multiple cities are located close to each other. However, developing synergies among these cities requires networking to optimize the critical mass and exploit complementarities. Much is expected of spatial planning in terms of fostering networks. However, little is known about the actual contribution planning may have in developing city networks, in particular, since it involves planning on a new scale and based upon new starting points and objectives. Exemplary is the territorial development strategy (1990s) of the Basque country aimed at developing the networking among its three main cities (Bilbao, San Sebastian and Vitoria) to develop a Basque ‘Global City’. We find that the leverage of this planning strategy has been poor, due to strong local identities and the lack of regional organizing capacity. This also appears to be common for other polycentric regions. 相似文献
107.
108.
Background
Coffee oil potently raises serum cholesterol levels in humans. The diterpenes cafestol and kahweol are responsible for this elevation. Coffee oil also causes elevation of liver enzyme levels in serum. It has been suggested that cafestol is mainly responsible for the effect on serum cholesterol levels and that kahweol is mainly responsible for the effect on liver enzyme levels. The objective of this study was to investigate whether coffee oil that only contains a minute amount of kahweol indeed does not cause elevation of liver enzyme levels. 相似文献109.
110.
Maria Bubb Anna-Sophia Lieselott Beyer Pooja Dasgupta Daniel Kaemmerer Jrg Snger Katja Evert Ralph M. Wirtz Stefan Schulz Amelie Lupp 《International journal of molecular sciences》2022,23(9)
In addition to the classical oestrogen receptors, ERα and ERβ, a G protein-coupled oestrogen receptor (GPER) has been identified that primarily mediates the rapid, non-genomic signalling of oestrogens. Data on GPER expression at the protein level are contradictory; therefore, the present study was conducted to re-evaluate GPER expression by immunohistochemistry to obtain broad GPER expression profiles in human non-neoplastic and neoplastic tissues, especially those not investigated in this respect so far. We developed and thoroughly characterised a novel rabbit monoclonal anti-human GPER antibody, 20H15L21, using Western blot analyses and immunocytochemistry. The antibody was then applied to a large series of formalin-fixed, paraffin-embedded human tissue samples. In normal tissue, GPER was identified in distinct cell populations of the cortex and the anterior pituitary; islets and pancreatic ducts; fundic glands of the stomach; the epithelium of the duodenum and gallbladder; hepatocytes; proximal tubules of the kidney; the adrenal medulla; and syncytiotrophoblasts and decidua cells of the placenta. GPER was also expressed in hepatocellular, pancreatic, renal, and endometrial cancers, pancreatic neuroendocrine tumours, and pheochromocytomas. The novel antibody 20H15L21 will serve as a valuable tool for basic research and the identification of GPER-expressing tumours during histopathological examinations. 相似文献