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排序方式: 共有6544条查询结果,搜索用时 15 毫秒
91.
Ki Bong LeeByung Hee Chun Jae Cheol LeeChan Ho Lee Sung Hyun Kim 《Chemical engineering science》2002,57(11):1923-1929
An experimental analysis of ammonia-water absorption was performed in a plate-type absorber. The flow of water and ammonia gas was performed in the bubble mode. The experiments were made to examine the effects of solution flow rate and gas flow rate on the performance of the absorber. It was found that the increase of solution flow rate rarely affected the mass transfer, but improved the heat transfer. As the gas flow rate increased, slugging occurred in the bubble mode and influenced the thermal boundary layer. Finally, the results were converted into dimensionless numbers to elucidate physical phenomena and plotted as Sherwood number versus Reynolds number for mass transfer performance and Nusselt number versus Reynolds number for heat transfer performance. 相似文献
92.
N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTCC), a water‐soluble chitosan quaternary ammonium derivative, was used as an antimicrobial agent for cotton fabrics. HTCC has a lower minimum inhibition concentration (MIC) against Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli compared to that of chitosan; however, the imparted antimicrobial activity is lost on laundering. Thus crosslinking agents were utilized to obtain a durable antimicrobial treatment by immobilizing HTCC. Several crosslinkers such as dimethyloldihydroxyethylene urea (DMDHEU), butanetetracarboxylic acid (BTCA), and citric acid (CA) were used with HTCC to improve the laundering durability of HTCC treatment by covalent bond formation between the crosslinker, HTCC and cellulose. The polycarboxylic acid treatment was superior to the DMDHEU treatment in terms of prolonged antimicrobial activity of the treated cotton after successive laundering. Also, the cotton treated with HTCC and BTCA showed improved durable press properties without excessive deterioration in mechanical strength or whiteness when compared to the citric acid treatment. With the addition of only 0.1% HTCC to BTCA solutions, the treated fabrics showed durable antimicrobial activity up to 20 laundering cycles. The wrinkle recovery angle and strength retention of the treated fabrics were not adversely affected with the addition of HTCC. Therefore, BTCA can be used with HTCC in one bath to impart durability of antimicrobial activity along with durable press properties to cotton fabric. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1567–1572, 2003 相似文献
93.
Jinkyung Kim Dookyo Jeong Changho Son Younghee Lee Eunyong Kim Il Moon 《Korean Journal of Chemical Engineering》2007,24(6):1076-1083
Three types of unsaturated polyester resins were synthesized from the glycolysis of polyethylene terephthalate (PET) plastic
waste, considering environment, cost and properties for their applications. These synthesized unsaturated polyester resins
could be used for various construction processes and materials such as no dig pipelining (NDR-1), pultrusion (PLR-1) and polymer
concrete (PCR-1). PET was taken from common soft-drink bottles, and ethylene glycol (EG), diethylene glycol (DEG) and MPdiol
glycol mixtures were used for the depolymerization at molar ratios. The glycolyzed PET 1
st
products (oligomers) were reacted with maleic anhydride, phthalic anhydride and dicyclopentadiene (DCPD) (especially for
polymer concrete) to form unsaturated polyester resins with mixed styrene. The lab scale (1–5 kg) and pilot plant scale-up
tests (200 kg) were experimented to evaluate the processing characteristics, viscosity, acid number and curing behaviors.
The main properties such as hardness, flexural strength, tensile strength, heat distortion temperature, elongation, and chemical
resistance were determined based on the various uses of the three resins. Furthermore, the applicability and the properties
of these developed resins were verified through many real application tests. 相似文献
94.
To understand the smart (i.e., good memory) characteristics of hybrid composites of carbon fibers (CFs) and glass fibers (GFs) with epoxy resin as a matrix, the changes in the electrical resistance of composites with tension and on bending were investigated. The electrical resistance behavior of composites under tension changed with the composition of the CF/GF, as well as with the applied strain. The fractional electrical resistance increased slowly with increasing strain within a relatively low strain region. However, with further loading it increased stepwise with the strain according to the fracture of the CF layers. The strain sensitivity of the samples increased with increasing CF weight percentage, and the samples incorporating more than 40 wt % CF showed a strain sensitivity higher than 1.54 for a single CF. The changes in the fractional electrical resistance with bending were not so dominant as those with tension. This difference was attributed to the action of two cancelling effects, which are the increasing and decreasing fractional electrical resistance due to tension and compression with bending, respectively. On recovery from a large applied bending, the fractional electrical resistance decreased slowly with unloading because of the increase of contacts between the fibers that resulted from the reorganization of ruptured CFs during the recovery. Even the composites incorporating a relatively small CF content showed an irreversible electrical resistance with both tension and bending. However, the strain sensitivity being larger with tension than with bending is ascribed to the difference in their mechanical behaviors. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2447–2453, 2002 相似文献
95.
Pillai Karthik Ganesh Ramaswamy Radhakrishnan Kanthavel Ramakrishnan Dhaya Yesudhas Harold Robinson Eanoch Golden Julie Kumar Raghvendra Long Hoang Viet Son Le Hoang 《Multimedia Tools and Applications》2021,80(5):7077-7101
Multimedia Tools and Applications - Detection and clustering of commercial advertisements plays an important role in multimedia indexing also in the creation of personalized user content. In... 相似文献
96.
Sang Chul Seo Hyun Jung Kim Byung Ho Park Kwang Suk Son Sung Keun Lee Sun Bae Kang Donggyu Kim 《Metals and Materials International》2006,12(3):273-277
In a continuous casting steelmaking operation, the surface of a slab is under a condition that can be characterized as high-temperature,
low-cycle fatigue in which the tensile and compressive stress is repeatedly developed. For this reason, for the evaluation
of the hot ductility of a slab, considering the fatigue deformation is more feasible before a tensile or compressive test.
In this study, the effects of low-cycle fatigue on the hot ductility of steels with a carbon content of 0.06–0.8 wt.% are
investigated at various temperatures. For a carbon content of 0.06%, there were no significant differences between the RA
values from a simple tensile test and those from a tensile test after fatigue deformation. The tendency of ductility deterioration
with fatigue deformation is evident in 0.1 %C steel, and is due to the deformation-induced ferrite film that forms around
the prior austenite grain. Conversely, high carbon steel containing 0.8 %C did not show a recovery of hot ductility in a low
temperature region, and the specimen on which the tensile was measured after fatigue showed a higher hot ductility in the
low temperature region, which is thought to result from the pearlite refinement effects. As the results obtained in this work
showed noticeable differences in the hot ductility of carbon steel through the test conditions, it is suggested that for more
accurate data, fatigue deformation be adopted in which the temperature range in an unbending operation is determined in the
steelmaking factory. 相似文献
97.
Jae?H.?KimEmail author Jung?M.?Lee Ho?C.?Shin Young?H.?Paik 《Metals and Materials International》2003,9(6):593-597
It is known that oxide inclusions in liquid metal carry mostly positive charges on their surfaces. In an electrostatic field,
therefore, such charged particles suspended in a liquid metal experience forces and accumulate in the region of the negatively
charged surface, resulting in the separation of oxide inclusions from the liquid metal. In this study, this principle was
experimentally demonstrated for the case of a capacitor cell by the imposition of a d.c. potential on electrodes. The capacitor
cell consisted of a dielectric container of Pyrex tube, a high voltage d.c. source, and two electrodes, which were symmetrically
attached onto the outer surface of the Pyrex. tube. Experiments were carried out for suspensions of liquid tin/metal oxides,
such as SnO2, WO3, and PbO under an applied potential of up to 12 kV. All experimental results were in good agreement with the theoretical
prediction and showed that the degree of separation was significantly increased with the applied potential. 相似文献
98.
Gate location design in injection molding of an automobile junction box with integral hinges 总被引:5,自引:0,他引:5
Polymers such as polypropylene or polyethylene offer a unique feature of producing an integral or living hinge for automobiles, which can flex over a million times without causing a failure. However, due to increased fluidity resistance at hinges during molding, several defects such as short shot or premature failure can occur with the improper selection of gate locations. In this paper, a design guideline was induced by investigating resin flow patterns depending on several gate positions obtained by numerical analyses of a simple strip with a hinge. The analyses of the simple strip part showed that the resin at the hinge did not flow until the other side of the strip was filled. Once the resin at the hinge did not flow for a long time enough to be solidified, defects such as short shots or hesitation marks formed. For a practical application of the design guideline determined, four gate systems for an automobile junction box were designed. It was found that the properly determined gate location leads to better resin flow and shorter hesitation time. Finally, injection molding tryouts using a mold that was designed by one of the proposed gate systems were conducted. The experiments showed that hinges without defects could be produced by using the designed gate location to assure the induced design guideline to be reasonable. 相似文献
99.
In the conventional metallothermic reduction (MR) process used to obtain tantalum powder in batch-type operation, it is difficult
to control the morphology and location of the tantalum deposits. In contrast, an electronically mediated reaction (EMR) process
is capable of overcoming this difficulty. It has the advantage of being a continuous process, but has the disadvantage of
a poor reduction yield. A process known as the MR-EMR combination process is able to overcome the shortcomings of the MR and
EMR processes. In this study, an MR-EMR combination process is applied to the production of tantalum powder via sodium reduction
of K2TaF7. In the MR-EMR combination process, the total charge passed through an external circuit and the average particle size (FSSS)
increase as the reduction temperature increases. In addition, the proportion of fine particles (−325 mesh) decreases as the
reduction temperature increasess. The tantalum yield improved from 65 to 74% as the reduction temperature increased. Taking
into account the charge, impurities, morphology, particle size and yield, a reduction temperature of 1123 K was found to be
optimum for the MR-EMR combination process. 相似文献
100.
Jae Woong Choi Gil Ho Hwang Won Kyu Han Sung Goon Kang 《Metals and Materials International》2006,12(1):75-80
Ni−B film of 1 μm thickness was electrolessly deposited on an electroplated Cu bus electrode. The film, which encapsulates
the Cu bus electrodes, prevents Cu oxidation and serves as a diffusion barrier against Cu contamination of the transparent
dielectric layer in a plasma display during the firing process at 580 °C. The microstructure of theas-deposited barrier film was amorphous phase and crystallized to Ni and Ni3B after annealing at 300 °C. The good barrier properties observed here can be explained by Ni3B precipitates at the grain boundaries acting as a fast diffusion path via pre-annealing at 300 °C before the firing process
at 580 °C. 相似文献