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141.
本文介绍了笔者设计并实现的一种新型的面向对象的程序设计语言,着重讨论了在设计过程中采用的新的概念,并和其它类似语言作了比较. 相似文献
142.
Present-day computer-aided design (CAD) packages play only a small part in the area of mechanical engineering design, which involves the synthesis and embodiment of physical components to perform a pre-determined function without unwanted side effects. The computer cannot properly help the designer in this task until it is able to capture and process the function requirements of the design. This paper describes the computer system being developed for this purpose at the Engineering Design Centre at Cambridge University Engineering Department. The paper also explores some of the geometrical and programming implications raised. 相似文献
143.
144.
C. A. Pineda P. Wenzl J. Mayer J. Mesjasz-Przybylowicz W. J. Przybylowicz V. M. Prozesky 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1997,130(1-4):362-367
A Brachiaria breeding project is being conducted at CIAT, Colombia to combine acid soil adaptation of B. decumbens with other favourable traits of Brachiaria species that are less adapted to acid soils. Micro-PIXE was applied to investigate nutrient uptake and distribution in root tips of different species grown in hydroponic culture under control and simulated acid soil stress conditions. Different sample measurement approaches were evaluated, including: (1) linear scans with single point measurements along the root axis; (2) mapping of whole root tips; and (3) mapping of root cross sections. Different tissue types could be distinguished on the base of differences in nutrient concentrations and/or Al stress. Al, if supplied under nutrient stress conditions, increased P accumulation in the central vascular tissue of the meristematic and elongation zone of B. decumbens and B. brizantha. Furthermore, a negative correlation was found between Al and Cl accumulation in the root cap of B. decumbens. 相似文献
145.
The paper describes a prototype system called HiSQL (Historical SQL) which extends the functionality of SQL in manipulating
historical data, by providing functions for spatial and temporal processing. Conceptually the paper is divided into three
parts: the first part deals with the design and architecture of the system; the second part introduces a case study (the defters);
and the third part describes specific functions for spatial and temporal processing of serial documents. The paper concludes
with a comparison between HiSQL and SQL and suggestions for further work.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
146.
147.
The behaviour of hydrogen permeation and diffusion in amorphous alloy Ni68Cr7Si8B14Fe3 hasbeen investigated by an ultrahigh vacuum gas permeation technique. A comparison experimentwas carried out between the as-quenched and annealed States (400℃/2h) of the amorphousalloy. The results show that, for both states of the amorphous alloy in the temperature rangeof 200~350℃, the diffusivity and permeability of hydrogen are in agreement with Arrheniusrelationship, there does not exist H-trapping effect, and the activation energies of diffusion andpermeation almost keep the same. 相似文献
148.
In this paper the results are presented of a test program on the energy absorption of composite cylinders loaded in compression. The influence of the laminate lay-up and of the trigger configuration were determined. Two different failure modes for the different laminates and triggers were observed: a splaying mode and a fragmentation mode. The splaying mode is more efficient in absorbing energy. The failure mode did not change during the crushing process. 相似文献
149.
Crystals of mixed NdLa heptamolybdates (max. size0.75×0.75×0.75 mm3) grown by silica gel technique were characterized using EDAX, IR, optical and scanning electron micrscopies.X-ray as well as electrn diffraction. The composition of the crystals was determined as (Nd1/2 La1/2 )2 Mo7O24·35H2O.The crystals exhibit varied morpholgies including square and octagonal platelets, cuboids, multifaceted crystal in coalesced and aggregated forms and spherulites.The XRD results indicate crystallinity of the grown material. Electron diffraction results suggest thermal instability of the material. IR results show the presence of peaks due to water and metal-oxygen bonds 相似文献
150.
Exchange and oxidation of C16O were investigated at 450°C on 18O-predosed Rh and Pt catalysts supported on A12O3, CeO2 and CeO2-Al2O3. In all cases, a rapid exchange of C16O with the surface can be observed. CO oxidation leads to C16O2, C16O18O and C18O2. Significant formation of C16O2 is due to the relatively high 16O coverage in reaction resulting from the C16O exchange and from an exchange between O surface species and 16O internal atoms. Hydrogen is also formed via a water-gas shift reaction (CO + surface OH) in higher proportion on CeO2-containing catalysts than on A12O3. Chlorine inhibits all the reactions (exchange, oxidation and WGS) and particularly the internal exchange. 相似文献