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Temperature Difference and Stack Plate Spacing Effects on Thermodynamic Performances of Standing-Wave Thermoacoustic Engines Driven by Cryogenic Liquids and Waste Heat

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Journal of Thermal Science 2022年第5期31卷 1434-1451页

作者： GUO Lixian ZHAO Dan BECKER sid Department of Mechanical Engineering College of EngineeringUniversity of CanterburyPrivate Bag 4800Christchurch8041New Zealand

The standing-wave thermoacoustic engines(TAE)are applied in practice to convert thermal power into acoustic one to generate electricity or to drive cooling *** there is a number of existing numerical researches that provides a design tool for predicting standing-wave TAE performances,few existing works that compare TAE driven by cryogenic liquids and waste heat,and optimize its performance by varying the stack plate *** present work is primarily concerned with the numerical investigation of the performance of TAEs driven by cryogenic liquids and waste *** this,three-dimensional(3-D)standing-wave TAE models are ***-and time-independence studies are conducted *** validations are then performed by comparing with the numerical results available in the *** validated model is then applied to simulate the standing-wave TAEs driven by the cryogenic liquids and the waste heat,as the temperature gradientΔT is *** is found that limit cycle oscillations in both systems are successfully generated and the oscillations amplitude is increased with increasedΔ*** is identified with acoustic streaming and the flow reversal occurring through the *** studied are then conducted between the cryogenic liquid-driven TAE and that driven by waste heat in the presence of the same temperature gradientΔ*** is shown that the limit cycle frequency of the cryogenic liquid system is 4.72%smaller and the critical temperatureΔT_(cri)=131 K is lower than that of the waste heat system(ΔT_(cri)=187 K).Furthermore,the acoustic power is increased by 31%and the energy conversion efficiency is found to increase by 0.42%.Finally,optimization studies on the stack plate spacing are conducted in TAE system driven by cryogenic *** is found that the limit cycle oscillation frequency is increased with the decreased ratio between the stack plate spacing and the heat penetration *** the ratio is set to between 2 and

关键词： thermoacoustic engine standing-wave cryogenic thermodynamics acoustical energy plate spacing heat transfer acoustic streaming

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SOME PROPERTIES OF m-ISOMETRIES AND m-INVERTIBLE OPERATORS ON BANACH SPACES

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Acta Mathematica Scientia 2012年第2期32卷 520-530页

作者： Ould Ahmed Mahmoud sid Ahmed Department of Mathematics College of ScienceAljouf UniversityAljouf 2014Saudi Arabia

This article has two purposes： the first is to give some structure results for the class of m-isometries, and the second purpose is to extend the notions of left and right inverses to m-left and m-right inverses resp... 详细信息

关键词： m-isometry m-left inverse m-right inverse approximate spectrum pointspectrum

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吃糖会让人快乐吗？

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广东第二课堂(下半月中学生阅读) 2024年第10期 33-33页

作者： sid

似乎每个小朋友都喜欢吃糖。我现在已经不算是小朋友了，但还是喜欢吃糖，喜欢吃各种甜品。我知道吃太多糖对身体不好，很多人都说要控糖，因此虽然喜欢，我也不敢敞开肚皮吃。我想知道，吃糖真的会让人快乐吗？—糖糖想必很多人都有这...

似乎每个小朋友都喜欢吃糖。我现在已经不算是小朋友了，但还是喜欢吃糖，喜欢吃各种甜品。我知道吃太多糖对身体不好，很多人都说要控糖，因此虽然喜欢，我也不敢敞开肚皮吃。我想知道，吃糖真的会让人快乐吗？—糖糖想必很多人都有这样的感受，当你正在为学习或生活烦恼时，喝上一口甜甜的奶茶，或者吃一口小蛋糕，过不了多久就会感觉心情变好，整个人又充满活力。这是由于，吃甜食的确会让人心情变好。

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为什么摸完硬币后，手上有一股金属味？

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广东第二课堂(下半月中学生阅读) 2024年第9期 32-32页

作者： sid 中科院物理所微信公众号答题团队

问我从小有收集硬币的习惯，前阵子把储钱罐的硬币倒出来数，数完后发现手上有一股金属味。我觉得有点奇怪，硬币明明没有味道呀，我手上的金属味从哪儿来的呢？这难道就是所谓“铜臭味”？—阿骐答正如你所说，硬币本身是没有味道的...

问我从小有收集硬币的习惯，前阵子把储钱罐的硬币倒出来数，数完后发现手上有一股金属味。我觉得有点奇怪，硬币明明没有味道呀，我手上的金属味从哪儿来的呢？这难道就是所谓“铜臭味”？—阿骐答正如你所说，硬币本身是没有味道的。常用的硬币材料有铜合金、镍合金、不锈钢等，这些都是金属材料，金属原子间结合力极强，常温下不会挥发形成气体分子，所以我们直接闻硬币是闻不到味道的。

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A robust model-free controller for a three-phase grid-connected photovoltaic system based on ultra-local model

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Protection and Control of Modern Power Systems 2021年第1期6卷 538-550页

作者： Ahsene Boubakir sid-Ahmed Touil Salim Labiod Nasserdine Boudjerda LAJ Faculty of Science and TechnologyUniversity of JijelBP.98Ouled Aissa18000JijelAlgeria Department of Electrical Engineering University of JijelJijelAlgeria LER Faculty of Sciences and TechnologyUniversity of JijelBP 98Ouled Aissa18000JijelAlgeria

In this paper, a robust model-free controller for a grid-connected photovoltaic (PV) system is designed. The system consists of a PV generator connected to a three-phase grid by a DC/AC converter. The control objectives of the overall system are to extract maximum power from the PV source, to control reactive power exchange and to improve the quality of the current injected into the grid. The model-free control technique is based on the use of an ultra-local model instead of the dynamic model of the overall system. The local model is continuously updated based on a numerical differentiator using only the input–output behavior of the controlled system. The model-free controller consists of a classical feedback controller and a compensator for the effects of internal parameter changes and external disturbances. Simulation results illustrate the efficiency of the controller for grid-connected PV systems.

关键词： Photovoltaic system Maximum power point Model-free control Ultra-local model Numerical differentiator

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COVID-19 and Learning Styles: GCET as Case Study

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Computers, Materials & Continua 2021年第7期68卷 103-115页

作者： Mazhar Hussain Malik sid Ahmed Amjed Sulaiman Al Hasani Department of Computing and Information Technology Global College of Engineering and TechnologyMuscatSultanate of Oman Department of Electrical and Electronics Engineering Global College of Engineering and TechnologyMuscatSultanate of Oman

The COVID-19 pandemic has caused higher educational institutions around the world to close campus-based activities and move to online *** aim of this paper is to present the case of Global College of Engineering and Technology(GCET)and how its practices including teaching,students/staff support,assessments,and exam policies were *** paper investigates the mediating role of no detriment policy impact on students’result along with the challenges faced by the higher educational institution,recommendations and *** investigation concludes that the strategies adopted for online delivery,student support,assessments and exam policies have helped students to effectively cope with the teaching and learning challenges posed by the COVID-19 pandemic without affecting their academic *** study shows that 99%of students were able to maintain the same or better level of performance during the 1st COVID-19 *** percent of students had shown a slight decrease in their performance(about 1%–2%)with respect to their overall marks *** no detriment policy has succoured those 1%of the students to maintain their overall performance to what it used to be pre-COVID-19 ***,the paper provides the list of challenges and suggestions for smooth conduction of online education.

关键词： Higher education learning styles COVID-19 challenges and strategies no detriment policy engineering and technology modules

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IPv6 Cryptographically Generated Address:Analysis,Optimization and Protection

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Computers, Materials & Continua 2021年第7期68卷 247-265页

作者： Amjed sid Ahmed Rosilah Hassan Faizan Qamar Mazhar Malik Department of Computing and Information Technology Global College of Engineering and TechnologyRuwi112Sultanate of Oman Faculty of Information Science and Technology Center for Cyber SecurityUniversiti Kebangsaan MalaysiaBangi43600Malaysia Faculty of Information Science and Technology Universiti Kebangsaan Malaysia43600BangiMalaysia

In networking,one major difficulty that nodes suffer from is the need for their addresses to be generated and verified without relying on a third party or public authorized *** resolve this issue,the use of selfcertifying addresses have become a highly popular and standardized method,of which Cryptographically Generated Addresses(CGA)is a prime *** was primarily designed to deter the theft of IPv6 addresses by binding the generated address to a public key to prove address *** though the CGA technique is highly effective,this method is still subject to several vulnerabilities with respect to security,in addition to certain limitations in its *** this study,the authors present an intensive systematic review of the literature to explore the technical specifications of CGA,its challenges,and existing proposals to enhance the *** that CGA generation is a time-consuming process,this limitation has hampered the application of CGA in mobile environments where nodes have limited energy and *** Hash2 conditions in CGA is the heaviest and most timeconsuming part of *** improve the performance of CGA,we replaced the Secure Hash Algorithm(SHA1)with the Message Digest(MD5)hash ***,this study also analyzes the possible methods through which a CGA could be *** conducting this analysis,Denial-of-Service(DoS)attacks were identified as the main method of attack toward the CGA verification process,which compromise and threaten the privacy of ***,we propose some modifications to the CGA standard verification algorithm to mitigate DoS attacks and to make CGA more security conscious.

关键词： IPv6 GCA SEND DoS attacks RSA SHA-1

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Robust direct power control based on the Lyapunov theory of a grid-connected brushless doubly fed induction generator

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Frontiers in Energy 2016年第3期10卷 298-307页

作者： M. Abdelbasset MAHBOUB Said DRID M. A. sid Ridha CHEIKH LSPIE Laboratory of Propulsion-Induction Electromagnetic Department Electrical Engineering University of Bama Batna 05000 Algeria LAS Laboratory Department of Electrical Engineering Setif UniversitySetif 19000 Algeria LGEB Laboratory Department of Electrical Engineering Biskra University Biskra 07000 Algeria UDES Unit6 de Drveloppement des Equipement Solaires Centre de eveloppement des Energies Renouvelables Tipaza 42415 Algeria

This paper deals with robust direct power control of a grid-connected bmshless doubly-fed induction generator（BDFIG）. Using a nonlinear feedback lineariza- tion strategy, an attempt is made to improve the desired performances by controlling the generated stator active and reactive power in a linear and decoupled manner. There- fore, to achieve this objective, the Lyapunov approach is used associated with a sliding mode control to guarantee the global asymptotical stability. Thus, an optimal operation of the BDFIG in sub-synchronous operation is obtained as well as the stator power flows with the possibility of keeping stator power factor at a unity. The proposed method is tested with the Matlab/Simulink software. Simulation results illustrate the performances and the feasibility of the designed control.

关键词： brushless doubly fed induction generator(BDFIG) vector control Lyapunov theory power factor unity active and reactive power

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Effects of Maternal Linseed Oil Supplementation on Metabolic Parameters in Cafeteria Diet-induced Obese Rats

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Biomedical and Environmental Sciences 2015年第4期28卷 298-302页

作者： BENAISSA Nawel MERZOUK Hafida MERZOUK sid Ahmed NARCE Michel Laboratory of Physiology and Biochemistry of Nutrition Department of Biology Faculty of Natural and Life SciencesEarth and Universe University Abou-Bekr Belka?d Department of technical Sciences Faculty of Engineering University Abou-Bekr Belka?d INSERM UMR 866 ‘Lipids Nutrition Cancer’ University of Burgundy Faculty of Sciences 6 Boulevard Gabriel Dijon 21000 France

Because linseed oil may influence maternal and fetal metabolisms, we investigated its role in the modulation of lipid metabolism in cafeteria diet-induced obese rats and their offspring. Female Wistar rats were fed control or cafeteria food, which were either supplemented or not supplemented with linseed oil （5%） for I month before and during gestation. At parturition, serum and tissue lipids and enzyme activities were analyzed. Cafeteria diet induced adverse metabolic alterations in both mothers and offspring. Linseed oil improved metabolic status. In conclusion, linseed oil displayed health benefits by modulating tissue enzyme activities in both obese mothers and their newborns.

关键词： OB Effects of Maternal Linseed Oil Supplementation on Metabolic Parameters in Cafeteria Diet-induced Obese Rats

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Blood Oxidant/Antioxidant Status in overfed Aging Rats: Comparative Effects of Sunflower and Olive-Linseed Mixture Oil Rich Diets

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Biomedical and Environmental Sciences 2013年第9期26卷 765-768页

作者： AYAD Amina MERZOUK Hafida MERZOUK sid Ahmed NARCE Michel Laboratory of Physiology and Biochemistry of Nutrition Department of Biology Faculty of Natural and Life SciencesEarth and Universe University Abou-Bekr Belkad Department of technical sciences Faculty of Engineering University Abou-Bekr Belkad INSERM UMR 866 "Lipids Nutrition Cancer"University of Burgundy Faculty of Sciences 6 Boulevard Gabriel

Obesity, one of the most common health problems, is associated with glucose and lipid metabolism abnormalities, increased cardiovascular risk and oxidative stressI1}. Aging is also associated with an increase in oxidative stress[2]. Considering that older adults are already at risk for oxidant stress, the additional metabolic perturbations of obesity aggravated the susceptibility to oxidant stress. Modulating age-related oxidative stress via dietary interventions could reduce free radical production and significantly improve health in aging.

关键词： Comparative Effects of Sunflower and Olive-Linseed Mixture Oil Rich Diets Blood Oxidant/Antioxidant Status in overfed Aging Rats CAF PUFA

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