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91.
The performance of communications networks can be monitored intrusively by transmitting test packets on the network links being tested. The delays experienced by these test packets and the number of test packets lost or duplicated may provide an indication of the performance of the links being monitored. Intrusive network monitoring, even at modest sampling rates, generates a significantly large amount of primitive data. This data needs to be summarised appropriately to address the required network performance analysis operations. These operations are generally iterative in nature, where the results of initial processing and analysis generate requirements for further processing and analysis. This paper describes the architecture of a database that can assist in efficient analysis of network performance by reusing the information derived at various stages. 相似文献
92.
A simple and low-cost process was devised to eliminate etch damage resulting from oxide etching on the seed-hole surface prior to selective epitaxial growth (SEG) of silicon. The process consists of a low power C 2F6 RIE step which was performed right after the oxide etch step in the same etch reactor. The use of this step excluded the need of a conventional sacrificial oxide to remove damaged silicon regions and residual polymers. The n-p diodes resulting from n-type SEG grown on p-type substrate were used to evaluate the quality of the silicon surface prior to SEG 相似文献
93.
VSb oxides diluted with Mg, Al and Zr displayed substantially higher selectivity for propane ammoxidation to acrylonitrile
than their bulk and supported analogues. Diluted catalysts were found to consist of oxide compounds of antimony with diluent
element, such as AlSbO4 or MgSb2O6, and small amounts of individual oxides of antimony and diluent element. No VSbO4 phase was detected in their body in contrast with bulk and supported catalysts. It appears that better isolation of vanadium
and antimony entities in the structure of diluted oxides was responsible for their enhanced catalytic behavior. Tungsten loaded
to the surface of diluted catalysts further improved their selectivity through tuning the surface acidity. 相似文献
94.
Shahid Bashir Philippe Taupin Stephen D. Antolovich 《Metallurgical and Materials Transactions A》1979,10(10):1481-1490
The continuous cycling and hold time low cycle fatigue properties of the Ni base superalloy René 95 were studied at 649°C
using powder products (−60 mesh) in the as-HIP and HIP + forged conditions. It was shown that cracks were initiated by pores,
by ceramic particles and by a classical stage I mechanism for both materials and for both cycle characters. For the continuously
cycled as-HIP material, deformation was restricted to well defined bands at low strains and became homogeneous as the strain
level increased. The total energy to fracture increased abruptly in the low strain regime and this was also reflected by a
break in the Coffin-Manson plot. In all cases cracks initiated at pores. The hold time specimens exhibited an extremely high
dislocation density and surface connected initiation yet without a significant life reduction. The observations were essentially
similar for the HIP + forged material except that deformation tended to be confined to well defined slip bands even at high
strains and to some extent even for the hold time tests. This behavior was attributed to the fact that theγ′ were smaller, more coherent and more readily sheared by dislocations which were strongly paired. There was a marked tendency
for crack propagation to change from transgranular to intergranular (also observed for the as-HIP material) at a unique combination
of crack length and plastic strain. The transition occurred at shorter crack lengths for the HIP + forged material except
when crack initiation was subsurface. In this case the transition was delayed and the life was greatly enhanced, indicating
that the environment plays a major role in determining the fatigue life.
PHILIPPE TAUPIN formerly Research Associate, Department of Materials Science, University of Cincinnati. 相似文献
95.
The most common cause for gastrointestinal bleeding of small bowel origin is angiodysplasia, followed by tumors of the small intestine, and various other causes, including small bowel ulcers and aortienteric fistulas. With the advent of improved diagnostic tests, including push and sonde enteroscopy, timely endoscopic diagnosis of these rare small bowel lesions has become possible, enabling the clinician to make better therapeutic decisions. This article focuses on the rare small bowel sources of intermittent and chronic gastrointestinal blood loss. 相似文献
96.
Parent material composition, particle disintegration by glaciers and lacustrine environment govern the geological development
and engineering characteristics of clay deposits in southern Saskatchewan. The pre-existing expansive clay minerals were preserved
due to the restrained leaching in the Regina Lake and the prevalent aridity in the area. The main objective of this paper
was to develop a fundamental understanding of the clay deposit for the use in the design and construction of civil infrastructure.
The results indicated the presence of expansive clay minerals in the deposit, with smectite accounting for 35% of the material.
The major exchangeable cation was found to be Ca2+ which accounted for more than half of the total measured cation exchange capacity of 40 (cmol(+)/kg). The most likely exchange
complex governing water adsorption of the clay was determined to be Ca2+-smectite. Alongside a high initial saturation (86%), this complex resulted in moderate volume changes in the clay. The swelling
pressure was fully developed within the first hour of the constant volume test. The corrected swelling pressure was determined
to be 120 kPa leading to an estimated heave of 36 mm in the surface layer of the deposit. The compression index and the swelling
index were found to be 0.25 and 0.08, respectively. 相似文献
97.
Norshahirah Mohamad Saidi Hong Ming Ng Fatin Saiha Omar Shahid Bashir K. Ramesh S. Ramesh 《应用聚合物科学杂志》2019,136(32):47810
New gel polymer electrolytes (GPEs) were prepared via the blending of a polyacrylonitrile polymer and a poly(1-vinyl pyrrolidone-co-vinyl acetate) copolymer. The sodium iodide (NaI) salt concentration was varied for each GPE sample. From ionic conductivity (σ) studies, we observed that the sample with a 40 wt % NaI salt content (N40) showed the highest σ of 3.54 × 10−3 ± 0.05 S/cm at room temperature, and all of the GPE samples obeyed Arrhenius behavior. The dielectric properties of the GPE samples were also analyzed to study the electrical polarization of the materials. The developed GPE samples were also characterized with X-ray diffraction and Fourier transform infrared spectroscopy. We also then used the developed GPE samples for the fabrication of dye-sensitized solar cells by sandwiching them between a photoanode and Pt counter electrode for photovoltaic studies. The highest photovoltaic performance was achieved by N40, with an efficiency of 3.04%. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47810. 相似文献
98.
99.
100.
Shabnum Shaheen Muhammad Asaf Khan Muhammad Afzal Naeem Muhammad Naveed Shahid Mehwish Jaffer Hanan Mukhtar 《Microscopy research and technique》2022,85(3):1194-1198
The anatomical variations of two plants from the Nyctaginaceae family, Bougainvillea spectabilis and Bougainvillea glabra, were studied using light and scanning electron microscopy methods in this work. Bougainvillea is a dicotyledonous with defensive traits that can withstand extreme (hot and dry) settings; according to the findings, crystal inclusions in cells, woody spines, and an abnormal development pattern are all features that help them survive against predators and are unique to this species. The Bougainvillea plant's leaves are arranged in simple pattern, alternate to each other along stem having an undulate leaves edge and an oval form. The xylem and phloem, palisade, parenchyma midrib, spongy mesophyll, raphide crystal bundles, and trichomes were all visible when bracts and leaves were transversally sectioned and dyed with toluidine blue O (TBO). The presence of crystals was confirmed by a detailed examination of the transverse leaves by using bright-field and cross-polarizing microscopy. Dissecting microscopic examination showed that all the leaves revealed leaves venation pattern that had midvein, lateral veins areoles, and trichomes. Although trichomes have been identified on both sides, a closer look at a cleaned leaf dyed with TBO showed multicellular abundant trichomes on adaxial surface. Stomata complexes were typically found on the abaxial surface of the leaf according to epidermal peels. Present studies also showed that on adaxial side, stomata were lesser in number or were absent and also showed that the morphologies of the pavement cells on the adaxial and abaxial sides of the leaf differed. 相似文献