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排序方式: 共有219条查询结果,搜索用时 62 毫秒
1.
The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the
minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed
fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The
carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in
palm oil were also isolated into their respective components, α-tocopherol, α-tocotrienol, γ-tocopherol, γ-tocotrienol, and
δ-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was
carried out and was found to be comparable to those analyzed by other established analytical methods. 相似文献
2.
Sit-Foon?Cheng Yuen-May?ChooEmail author Ah-Ngan?Ma Cheng-Hock?Chuah 《Journal of the American Oil Chemists' Society》2005,82(11):791-795
Rapid synthesis of high-purity MAG from refined, bleached, and deodorized palm stearin (RBDPS) via chemical glycerolysis in the presence of pyridine was developed to obviate the conventional molecular distillation in the
production of pure MAG. The optimal reaction for the sodium methoxide-catalyzed glycerolyis of RBDPS was recorded at 110°C
using a 3 wt% catalyst concentration based on the weight of RBDPS, with an RBDPS/glycerol ratio of 1∶2 and an RBDPS/pyridine
ratio of 1∶4. High yields of over 99% were achieved rapidly in 15 min, and increases in DAG and FFA were observed after a
prolonged reaction time. 相似文献
3.
C. S. Lee T. L. Ooi C. H. Chuah S. Ahmad 《Journal of the American Oil Chemists' Society》2007,84(12):1161-1167
A new type of rigid polyurethane foam was produced by incorporating oxazolidone heterocyclic rings on to polyurethane backbones.
Epoxidized diethanolamides were synthesized by reacting palm oil blends of epoxidized palm olein and refined bleached deodorized
palm kernel olein with diethanolamine to produce rigid polyurethane foams. Epoxides, retained in the diethanolamides, reacted
with isocyanate during foam production in the presence of AlCl3–THF complex catalyst to form oxazolidone linkages in the polyurethane network. The carbonyl stretch of oxazolidone was identified
at 1,750 cm−1 through Fourier Transform Infra Red analysis. Chemical modifications of the polyurethane network also improved the thermal
and mechanical properties of the foams. In addition, isocyanate index 1.4 was determined to be the most suitable in the production
of foams from this newly synthesized epoxidized diethanolamides. 相似文献
4.
Guanyao Huang Ashwin Lall Chen-Nee Chuah Jun Xu 《Journal of Network and Systems Management》2011,19(1):84-110
Discovering icebergs in distributed streams of data is an important problem for a number of applications in networking and
databases. While previous work has concentrated on measuring these icebergs in the non-distributed streaming case or in the
non-streaming distributed case, we present a general framework that allows for distributed processing across multiple streams
of data. We compare several of the state-of-the-art streaming algorithms for estimating local elephants in the individual
streams. However, since an iceberg may be hidden by being distributed across many different streams, we add a sampling component
to handle such cases. We provide a novel taxonomy of current sketches and perform a thorough analysis of the strengths and
weaknesses of each scheme under various QoS metrics, using both real and synthetic Internet trace data. We summarize their
performance and discuss the implications for the future design of sketches. 相似文献
5.
Image interpolation is one of the key technologies in image/video processing. In this study, a new adaptive image interpolation algorithm is proposed. The objective of the proposed approach is to recover up-sampled image frames from the corresponding decimated (low-resolution) image frames. In the proposed approach, within each iteration, two proposed nonlinear filters are utilized to iteratively generate high-frequency components lost within the decimation procedure. Finally, a post-processing procedure is adopted to reduce the blocking artifacts within the interpolated images. Based on the experimental results obtained in this study, in terms of the average PSNRp (peak signal-to-noise ratio) in dB and subjective measure of the quality of the interpolated images, the interpolation results by the proposed approach are better than that by three existing interpolation approaches for comparison. 相似文献
6.
Effect of Multi-Wall Carbon Nanotubes on the Mechanical Properties of Natural Rubber 总被引:1,自引:0,他引:1
Muataz Ali Atieh Nazlia Girun El-Sadig Mahdi Hairani Tahir Chuah Teong Guan Maan Fahmi Alkhatib Fakhru'l-Razi Ahmadun Dayang Radia Baik 《Fullerenes, Nanotubes and Carbon Nanostructures》2006,14(4):641-649
Multi-walled carbon nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/NR nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, elongation at break and hardness were studied. Mechanical test results show an increase in the initial modulus for up to 12 times in relation to pure NR. In addition to mechanical testing, the dispersion state of the MWNTs into NR studied by Transmission Electron Microscopy (TEM) in order to understand the morphology of the resulting system 相似文献
7.
In this paper, we propose to use the autoregressive (AR)-based interpolator with Wiener filter and apply the idea to scanning electron microscope (SEM) images. The concept for combining the AR-based interpolator with Wiener filtering comes from the essential requirement of Wiener filtering for accurate and consistent estimation of the power of the noise in images prior to filter implementation. The resultant filter is called AR-Wiener filter. The proposed filter is embedded onto the frame grabber card of the scanning electron microscope (SEM) for real-time image processing. Different images are captured using SEM and used to compare the performances of the conventional Wiener and the proposed AR-Wiener technique. 相似文献
8.
9.
Carlos Colman-Meixner Ferhat Dikbiyik M. Farhan Habib Massimo Tornatore Chen-Nee Chuah Biswanath Mukherjee 《Photonic Network Communications》2014,27(3):141-153
Cloud-computing services are provided to consumers through a network of servers and network equipment. Cloud-network (CN) providers virtualize resources [e.g., virtual machine (VM) and virtual network (VN)] for efficient and secure resource allocation. Disasters are one of the worst threats for CNs as they can cause massive disruptions and CN disconnection. A disaster may also induce post-disaster correlated, cascading failures which can disconnect more CNs. Survivable virtual-network embedding (SVNE) approaches have been studied to protect VNs against single physical-link/-node and dual physical-link failures in communication infrastructure, but massive disruptions due to a disaster and their consequences can make SVNE approaches insufficient to guarantee cloud-computing survivability. In this work, we study the problem of survivable CN mapping from disaster. We consider risk assessment, VM backup location, and post-disaster survivability to reduce the risk of failure and probability of CN disconnection and the penalty paid by operators due to loss of capacity. We formulate the proposed approach as an integer linear program and study two scenarios: a natural disaster, e.g., earthquake and a human-made disaster, e.g., weapons-of-mass-destruction attack. Our illustrative examples show that our approach reduces the risk of CN disconnection and penalty up to 90 % compared with a baseline CN mapping approach and increases the CN survivability up to 100 % in both scenarios. 相似文献
10.