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排序方式: 共有468条查询结果,搜索用时 140 毫秒
461.
Various factors, including starch granule channels, have been suggested to contribute to the control of sorghum starch digestibility for animal feed. Isolated starch from two normal sorghum lines (P721N, IS6986) and one high protein digestibility (HPD) mutant line (111) that differed in starch granule morphology were selected to study the influence of these factors on starch digestibility. Scanning electron micrographs were taken of raw and digested starches. Microscopy results confirmed that in all three sorghum lines channels in starch granules are the main route of enzyme penetration and the central cavity area is the starting point of enzyme digestion. Channel density was more pronounced in the HPD sorghum mutant line than in normal lines, which may have been responsible for its relatively high digestibility. Micrographs of IS6986 showed unique starch granule morphology with a collapsed ”doughnut‐shaped” structure in a portion of the granules. These unusual granules were rapidly digested and, unlike normal spherical granules, totally disappeared after 30 min of digestion. Amylases appeared to have fast access to the collapsed‐appearing starch granules. Digestion profiles, following incubation with pepsin and α‐amylase, showed that IS6986 and the HPD mutant (111) had the highest initial rate of starch digestion, followed by P721N. These findings provide insight as to how new sorghum cultivars might be developed with high starch digestibility for animal feed use. 相似文献
462.
Rabah Ouchikh Thierry Chonavel Abdeldjalil Aïssa-El-Bey Mustapha Djeddou 《International Journal of Communication Systems》2023,36(16):e5579
This paper proposes a new pilot pattern in the delay-Doppler (DD) domain for the orthogonal time frequency space (OTFS) system. In contrast to the embedded-pilot schemes, guard intervals are not used so as increase the spectral efficiency. Also, compared to the superimposed design where data symbols and pilots are arranged on the entire DD grid, in the proposed rearrangement, the number of pilots used is only spread over a subgrid of the DD grid. Hence, the interference of pilots with data symbols is reduced. Afterwards, an algorithm for channel estimation (CE) and symbol detection in the DD domain benefiting from the sparsity of the DD channel is designed. The sparse CE step is formulated as a specific marginalization of the maximum a posteriori (MAP) criterion by providing a Bayesian approach via the mean-field approximation that involves the variational Bayesian expectation maximization (VB-EM) algorithm. Detection of data symbols is done using a low complexity MP algorithm. We also propose an interference cancellation (IC) scheme to mitigate contamination of data by pilots that is run after each CE step. To achieve a high CE accuracy, based on the mean mutual incoherence property (MIP), a pilot optimization problem for OTFS is formulated and develop a simulated annealing-based algorithm to solve it. Finally, simulation results show that the proposed scheme achieves a good compromise between spectral efficiency, complexity, and performance in terms of bit error rate (BER) and normalized mean square error (NMSE) when compared to literature benchmarks. 相似文献
463.
Yang Wang Xiang Luo Li Chen Abdullateef Taiye Mustapha Xiaojie Yu Cunshan Zhou Clinton Emeka Okonkwo 《Comprehensive Reviews in Food Science and Food Safety》2023,22(1):615-642
For health and safety concerns, traditional high-calorie sweeteners and artificial sweeteners are gradually replaced in food industries by natural and low-calorie sweeteners. As a natural and high-quality sugar substitute, steviol glycosides (SvGls) are continually scrutinized regarding their safety and application. Recently, the cultivation of organic stevia has been increasing in many parts of Europe and Asia, and it is obvious that there is a vast market for sugar substitutes in the future. Rebaudioside A, the main component of SvGls, is gradually accepted by consumers due to its safe, zero calories, clear, and sweet taste with no significant undesirable characteristics. Hence, it can be used in various foods or dietary supplements as a sweetener. In addition, rebaudioside A has been demonstrated to have many physiological functions, such as antihypertension, anti-diabetes, and anticaries. But so far, there are few comprehensive reviews of rebaudioside A. In this review article, we discuss the physicochemical properties, metabolic process, safety, regulatory, health benefits, and biosynthetic pathway of rebaudioside A and summarize the modification methods and state-of-the-art production and purification techniques of rebaudioside A. Furthermore, the current problems hindering the future production and application of rebaudioside A are analyzed, and suggestions are provided. 相似文献
464.
Leszek Szczecinski Fatou‐Kin Diop Mustapha Benjillali 《Wireless Communications and Mobile Computing》2008,8(7):963-972
Hybrid ARQ with packet combining for high‐order modulations (such as 16‐QAM) may be significantly enhanced if the bits‐to‐symbols mappings are appropriately changed throughout the transmissions. In this paper, we analyze the relationship between such mapping diversity and channel coding. We calculate the capacity of the popular bit‐interleaved‐coded modulation (BICM) to draw qualitative and approximate quantitative conclusions that are valid for strong codes approaching the capacity limits. We conclude that the choice/design of the appropriate mapping depends on the targeted spectral efficiency and we demonstrate that certain forms of mapping diversity may be counterproductive. We also show that iterative demapping may be successfully applied to significantly reduce (by more than 1 dB) the gap between the BICM and coded modulations (CM) capacities. The analysis is illustrated with results obtained when the mapping diversity is combined with practical turbo codes. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
465.
Nayad Abdallah Hasnaoui Ali Hadouch Youness Fkhar Lahcen Idouhli Rachid Abdessalam Abouelfida Mehdi Ahmad Dikici Burak Mezzane Daoud Firdoussi Larbi El Ait Ali Mustapha 《SILICON》2023,15(1):321-335
Silicon - Silicon is one of the most used materials in semiconductors and electronic devices. Its miniaturization in two-dimensional (2D) scale is now a great challenge to improve and/or extend its... 相似文献
466.
Marjaoui Adil Ait Tamerd Mohamed Diani Mustapha El Kasmi Achraf Zanouni Mohamed 《Journal of Computational Electronics》2022,21(3):582-589
Journal of Computational Electronics - Two-dimensional materials offer the potential to attain nanoscale optoelectronic and thermoelectric devices. In this paper, the electronic structure and... 相似文献
467.
468.
Mohamed Saad Abdelmadjid Maali Mohamed Salah Azzaz Mustapha Benssalah 《International Journal of Communication Systems》2023,36(11):e5510
The work presented in this paper aims to develop a low-cost ultra-wideband (UWB) radar system that has the capability to image through the wall of a human target. The proposed radar system relies heavily on a field-programmable gate array (FPGA) platform. The Xilinx FPGA Kintex-7 (KC705) board is employed to integrate the main functionalities of the radar system, such as the generation and acquisition of a UWB signal. The generated signal is a monocycle signal, which has an ultra-wide bandwidth. Due to the UWB nature of this signal, the radar system achieves better penetration ability, as well as high imaging resolution. However, the major challenge of a UWB radar system lies in the stage of digitization, as it requires a high sampling rate analog-to-digital converter (ADC). In fact, such a chip is very expensive. Hence, to reach a high sampling resolution using a low-cost and low-speed ADC, an efficient sampling strategy is implemented. In contrast to other UWB sampling methods, which require a hardware delay line chip, the new sampling scheme depends only on the FPGA firmware to realize a combination of real-time and equivalent-time sampling, which provides better jitter performance. Finally, to demonstrate the imaging capability, experimental tests are conducted in an indoor environment while human targets are located in different places. The measurement results revealed that the proposed radar system has the ability to provide 2D images that accurately determine the location of the target. 相似文献