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921.
An adaptable die is one that not only produces the correct geometrical shape, but also is designed through an adaptable method to impart other desirable properties to the product or process. In this first part of a series of papers, six kinematically admissible velocity fields are developed for use in upper bound models for axisymmetric extrusion through various dies, including extrusion through adaptable dies. Three base velocity fields are presented:
- (1) assuming proportional angles in the deformation zone,
- (2) assuming proportional areas in the deformation zone, or
- (3) assuming proportional distances from the centerline in the deformation zone.
922.
Cunsheng Ding Niederreiter H. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(6):2274-2277
In this correspondence, two classes of cyclotomic linear codes over GF(q) of order 3 are constructed and their weight distributions are determined. The two classes are two-weight codes and contain optimal codes. They are not equivalent to irreducible cyclic codes in general when q > 2. 相似文献
923.
El-Husseini M.H. Venet P. Rojat G. Joubert C. 《Industry Applications, IEEE Transactions on》2002,38(3):713-718
In this paper, the authors use an analytical model to calculate the losses in the metallized polypropylene film capacitors. The model is validated experimentally for capacitors having the same capacitance but different geometry. For each group of capacitors, a temperature distribution in the roll is assumed with the aim of optimizing its thermal performance. It appears that the heating of a long capacitor is higher than that of an equivalent flat capacitor subjected to the same electric stresses 相似文献
924.
PROCESSING AND QUALITY EVALUATION OF WHOLE CANNED 'DWARF' GOLDEN APPLES (SPONDIAS CYTHEREA) 总被引:1,自引:0,他引:1
DAVID RAMSUNDAR EDWARD COMISSIONG NEELA BADRIE GAIL S.H. BACCUS-TAYLOR JOHN SPENCE 《Journal of food quality》2002,25(1):13-25
‘Dwarf’ golden apples (Spondias cytherea) were canned in sucrose syrup of either 30 d?Brix (L) or 40 d?Brix (H). Processing was either by hot filling (HF) of syrup at 92C in filled cans or by steam‐exhausting (SE) of the filled cans at 85C for 12–14 min, followed by processing at 100C for 20 min (W20) or 30 min (W30). Sensory evaluation of commercial sterile products, SE‐LW30 and SE‐LW30 indicated there were no differences (P < 0.05) in appearance, color, taste, aroma and texture. Overall scores indicated that fruits in syrup were liked definitely to like slightly. Panelists indicated that they might or definitely will purchase the products. Fruits in 40 d?Brix syrup were firmer than in 30 d?Brix syrup. By week 8 of storage at 28–30C, pH was stable between 3.6–3.7, and ‘cut‐out’d?Brix of syrup for LW30 and HW30 products was 24.0 – 24.5 and 28.5, respectively. 相似文献
925.
926.
H. Safiri M. Ahmadi G.A. Jullien W.C. Miller 《The Journal of VLSI Signal Processing》2002,31(2):91-100
A new algorithm based on Genetic Programming (GP) for the problem of optimization of Multiple constant Multiplication (MCM) by Common Subexpression Elimination(CSE) is developed. This method is used for hardware optimization for DSP systems. A solution based on Genetic Programming is shown in this paper. The performance of the technique is demonstrated in one- and multi-dimensional digital filters with constant coefficients. 相似文献
927.
Pressure-volume-temperature (PVT) properties are critical to reservoir as well as production engineers, in particular. PVT properties could be determined experimentally. But, experiments are time consuming and costly. Moreover, laboratory PVT analysis does not consider the variations of PVT properties with respect to temperature since they are measured at reservoir temperature at the time of sampling. For that matter, the data is not benefitable. But, even if experimental analysis is done, it is difficult to obtain representative results to develop a new field. To tackle the above and other related problems, relying on sound PVT emperical correlations would be the ultimate solution. In this work, the intent is to develop stochastic models for PVT properties pertaining to Omani crude oils since it is believed that such correlations are scarce and not very precise. The empirical equations are developed for saturated Omani crude oils. The correlations are tested and validated. The empirical equations evaluation and assessment are done against existent experimental data and published correlations. 相似文献
928.
S. Abiraman H. K. Varma T. V. Kumari P. R. Umashankar Annie John 《Bulletin of Materials Science》2002,25(5):419-429
This study investigates quantitatively and qualitatively the sol-gel derived bioactive glass-ceramic system (BGS)—apatite-wollastonite
(AW) type granules in the size range of 0.5–1 mm, as an effective graft material for bone augmentation and restoration. Scanning
electron micrographs (SEM) of the sintered granules revealed the rough material surface with micropores in the range 10–30
μm. X-ray diffraction (XRD) pattern of the granules revealed the presence of crystalline phases of the hydroxyapatite and
wollastonite, and the functional groups of the silicate and phosphates were identified by Fourier transform infrared spectroscopy
(FT-IR). Thein vitro cell culture studies with L929 mouse fibroblast cell line showed very few cells adhered on the BGS disc after 24 h. This
could be due to the highly reactive surface of the disc concomitant with the crystallization but not due to the cytotoxicity
of the material, since the cellular viability (MTT assay) with the material was 80‰ Cytotoxicity and cytocompatibility studies
proved that the material was non-toxic and biocompatible. After 12 weeks of implantation of the BGS granules in the tibia
bone of New Zealand white rabbits, the granules were found to be well osteointegrated, as observed in the radiographs. Angiogram
with barium sulphate and Indian ink after 12 weeks showed the presence of microcapillaries in the vicinity of the implant
site implicating high vascularity. Gross observation of the implant site did not show any inflammation or necrosis. SEM of
the implanted site after 24 weeks revealed good osteointegration of the material with the newly formed bone and host bone.
New bone was also observed within the material, which was degrading. Histological evaluation of the bone healing with the
BGS granules in the tibial defect at all time intervals was without inflammation or fibrous tissue encapsulation. After 2
weeks the new bone was observed as a trabeculae network around the granules, and by 6 weeks the defect was completely closed
with immature woven bone. By 12 weeks mature woven bone was observed, and new immature woven bone was seen within the cracks
of the granules. After 24 weeks the defect was completely healed with lamellar bone and the size of the granules decreased.
Histomorphometrically the area percentage of new bone formed was 67.77% after 12 weeks and 63.37% after 24 weeks. Less bone
formation after 24 weeks was due to an increased implant surface area contributed by the material degradation and active bone
remodeling. The osteostimulative and osteoconductive potential of the BGS granules was established by tetracycline labelling
of the mineralizing areas by 2 and 6 weeks. This sol-gel derived BGS granules proved to be bioactive and resorbable which
in turn encouraged active bone formation. 相似文献
929.
930.
Developing competency-based methods for near-real-time air combat problem solving assessment 总被引:1,自引:0,他引:1
Air combat scenarios present unique problems where the solution is not obvious. An advanced networked simulation environment can be used to train high-level cognitive air combat skills such as problem solving. A problem in the development of principled and construct oriented assessment is related to determining the level of specificity of the assessment. We present a detailed discussion of the definition of critical competencies associated with combat mission problem solving performance, and we describe our approach to develop and implement an embedded performance assessment system that maps outcomes to these competencies. Finally, we discuss the implications for our approach for comprehensive assessment and discuss our goals for an evaluation of the competency-based approach to assessment. 相似文献