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排序方式: 共有360条查询结果,搜索用时 265 毫秒
321.
322.
D. B. Kupranycz M. A. Amer B. E. Baker 《Journal of the American Oil Chemists' Society》1986,63(3):332-337
To evaluate the thermal oxidative behavior of butterfat in comparison to selected vegetable oils, samples of winter and summer
butterfat, liquid and solid butterfat fractions, and selected vegetable oils were heated at 185 C in the presence of air (30
ml/min) for 8 and 16 hr. The resultant heated fats and oils, as well as the methyl esters of their fatty acids, were examined
by gel permeation chromatography. The results indicated that butterfat is much more stable to thermal oxidation than canola,
sunflower and soybean oils. This was evidenced by a substantially higher content of both dimeric and higher oligomeric triglycerides
in the vegetable oils than in any of the butterfat samples after both 8 and 16 hr of heating. The corn oil also exhibited
a high degree of stability to thermal oxidation after 8 hr of heating. The 16 hr corn oil data, however, was less certain
due to the presence of a very viscous and dark colored material which could not be removed from the oxidation flask; this
was believed to contain highly polymerized oil and was not observed with any of the other samples. There were some differences
in the inter- and intramolecular polymerization of the butterfat fractions compared with each other and with whole butterfat.
With the winter butterfat samples, after 8 hr of thermal oxidation, both the solid and liquid butterfat fractions exhibited
more stability toward intermolecular polymerization than did the whole butterfat. After 16 hr of heating the ratio of trimeric
and higher oligomeric triglycerides to dimeric triglycerides increased with increasing degree of unsaturation of the butterfat
and with increased time of heating. Similar trends were observed with regard to the degree of intramolecular polymerization.
Presented at the AOCS meeting in Philadelphia in May 1985. 相似文献
323.
Amer Hassanein Hamed Iyer Ravishankar Krishnan 《Reliability, IEEE Transactions on》1986,35(4):377-379
This paper investigates the effect of uncertainty in chip failure rates on memory system reliability. It is shown, using real data on memory failures, that the dispersion in failure rates can be as large as 80%. An important consequence is to increase the unreliability of a memory system by up to 65%. Two simple models are proposed to evaluate the variability in memory reliability. The first is a worst case estimate and the second is a probabilistic model which needs only the mean and the standard deviation of the chip failure rate. With high failure rates, the maximum uncertainty in reliability occurs in the early system lifetime; with low failure rates, this effect is reversed. 相似文献
324.
In this paper, we suggested and studied the inverse length biased Maxell distribution (ILBMD) as a new continuous distribution of one parameter. The ILBMD is obtained by considering the inverse transformation technique of the Maxwell length biased distribution. Statistical characteristics of the ILBMD such as the moments, moment generating function, mode, quantile function, the coefficient of variation, coefficient of skewness, Moors and Bowley measures of kurtosis and skewness , stochastic ordering, stress-strength reliability, and mean deviations are obtained. In addition, the Bonferroni and Lorenz curves, Gini index, the reliability function, the hazard rate function, the reverse hazard rate function, the odds function, and the distributions of order statistics for the ILBMD, are presented. The ILBMD parameter is estimated using the maximum likelihood method, the method of moments, the maximum product of spacing technique, the ordinary and weight least square procedures, and the Cramer-Von-Mises methods. The Fishers information, as well as the Rényi and q-entropies, are derived. To investigate the usefulness of the proposed lifetime distribution and to illustrate the purpose of the study, a real dataset of the relief times of 20 patients receiving an analgesic is used. 相似文献
325.
The Globus Replica Location Service: Design and Experience 总被引:1,自引:0,他引:1
Chervenak Ann L. Schuler Robert Ripeanu Matei Amer Muhammad Ali Bharathi Shishir Foster Ian Iamnitchi Adriana Kesselman Carl 《Parallel and Distributed Systems, IEEE Transactions on》2009,20(9):1260-1272
Distributed computing systems employ replication to improve overall system robustness, scalability, and performance. A Replica Location Service (RLS) offers a mechanism to maintain and provide information about physical locations of replicas. This paper defines a design framework for RLSs that supports a variety of deployment options. We describe the RLS implementation that is distributed with the Globus Toolkit and is in production use in several Grid deployments. Features of our modular implementation include the use of soft-state protocols to populate a distributed index and Bloom filter compression to reduce overheads for distribution of index information. Our performance evaluation demonstrates that the RLS implementation scales well for individual servers with millions of entries and up to 100 clients. We describe the characteristics of existing RLS deployments and discuss how RLS has been integrated with higher-level data management services. 相似文献
326.
Similar to TCP and UDP, the stream control transmission protocol (SCTP) is a transport protocol providing end-to-end communication. SCTP was originally designed within the IETF Signaling Transport (SIGTRAN) working group to address TCP's shortcomings relating to telephony signaling over IP networks. SCTP has since evolved into a general-purpose IETF transport protocol with kernel implementations on various platforms. Similar to TCP, SCTP provides a connection-oriented, reliable, full- duplex, congestion and flow-controlled layer 4 channel. Unlike both TCP and UDP, however, SCTP offers new delivery options that better match diverse applications' needs. Here, we introduce SCTP, discuss its innovative services, and outline ongoing SCTP-related research and standardization activities. 相似文献
327.
Noor Hafizah Amer Hairi Zamzuri Khisbullah Hudha Zulkiffli Abdul Kadir 《Journal of Intelligent and Robotic Systems》2017,86(2):225-254
Autonomous vehicle field of study has seen considerable researches within three decades. In the last decade particularly, interests in this field has undergone tremendous improvement. One of the main aspects in autonomous vehicle is the path tracking control, focusing on the vehicle control in lateral and longitudinal direction in order to follow a specified path or trajectory. In this paper, path tracking control is reviewed in terms of the basic vehicle model usually used; the control strategies usually employed in path tracking control, and the performance criteria used to evaluate the controller’s performance. Vehicle model is categorised into several types depending on its linearity and the type of behaviour it simulates, while path tracking control is categorised depending on its approach. This paper provides critical review of each of these aspects in terms of its usage and disadvantages/advantages. Each aspect is summarised for better overall understanding. Based on the critical reviews, main challenges in the field of path tracking control is identified and future research direction is proposed. Several promising advancement is proposed with the main prospect is focused on adaptive geometric controller developed on a nonlinear vehicle model and tested with hardware-in-the-loop (HIL). It is hoped that this review can be treated as preliminary insight into the choice of controllers in path tracking control development for an autonomous ground vehicle. 相似文献
328.
O. M. Hemeda M. A. Amer S. A. Olofa M. M. Mosaad 《Journal of Materials Science: Materials in Electronics》1994,5(5):284-286
A series of samples of the system Co0.6Zn0.4Cu
x
Fe2 –x
O4 (x=0, 0.2, 0.4, 0.6 and 0.8) were prepared by the usual ceramic technique, X-ray analysis showed that the samples were cubic spinels (single phase). The lattice parameter, the theoretical density,D
x, the bulk density,D, and the porosity, p, were measured for the samples. The lattice parameter increased with the increase in Cu. Increases in the population of Fe2+ ions in octahedral sites with the introduction of Cu2+ resulted in increases in the lattice parameter. Differential thermal analysis (DTA) traces showed that there were exothermic peaks for the samples in the temperature range 120–190 C. 相似文献
329.
Taha A. Elwi Daniya Amer Jassim Hayder Hassan Mohammed 《International Journal of Communication Systems》2020,33(6)
This paper presents a design of an ultra‐wideband (UWB) cylindrical metamaterial (MTM) antenna for radio frequency (RF) energy harvesting to suit the fields of Internet of Things (IoT) applications. The patch circuitry is based on 3×5 Hilbert‐shaped MTM unit cells array to enhance the antenna bandwidth. While, the antenna ground plane is defected with an electromagnetic band gap structure to enhance the gain. The antenna is mounted on a polytetrafluoroethylene cylindrical substrate of an outer diameter of 15 mm and length of 32 mm with 1 mm in thickness. The substrate relative permittivity is 2.04, and the loss tangent is 0.0002. The antenna patch and the ground plane structures are printed with silver nanoparticles ink using a 2.5D CNC plotter machine. The fabricated prototype provides an UWB over the frequency range from 3.77 up to 13.89 GHz with a first separate resonant mode at 3 GHz. The antenna performance is tested numerically using two different software packages of CST MWS and HFSS. Then, an experimental validation is conducted to realize the performance of the proposed antenna in harvesting the RF energy. Excellent conversion efficiency, about 90%, is achieved at 5.8 GHz. Finally, the antenna radiation patterns and S11 spectrum are measured and compared against their simulated results to achieve good agreements. 相似文献
330.
Neural Processing Letters - Capsule network (CapsNet) was introduced as an enhancement over convolutional neural networks, supplementing the latter’s invariance properties with equivariance... 相似文献