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COmPARISON OF TWO mETHODS TO INCREASE TIP CLEARANCE AND ITS EFFECT ON PERFORmANCE OF TURBOCHARGER CENTRIFUGAL COmPRESSOR STAGE

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Chinese Journal of mechanical Engineering 2007年第4期20卷 60-65页

作者： syed Noman Danish School of mechanical and Vehicular Engineering Beijing Institute of TechnologyBeijing 100081China

Tip clearance between the blade tip and casing of a centrifugal compressor can be varied through two methods： by changing the blade height （mI） or by changing the casing diameter （m2）. Numerical simulations are carried out to compare these two methods and their effect on the stage and impeller performance. The impeller and diffuser are connected through rotor stator boundary using frozen rotor approach. Overall stage performance and the flow configuration have been investigated for nine tip clearance levels from no gap to 1 mm. Impeller and diffuser performances are also presented separately. It has been found that the overall and impeller performance are comparatively better for mI below tip clearance of 0.5 mm whereas m2 is found advantageous above 0.5 mm of tip clearance. Both mI and m2 show performance degradation with the increase in tip clearance. Two models have been proposed for the stage total pressure ratio and efficiency, which are found to be in agreement with experimental results. The impeller efficiency and the pressure ratio are found to be maximum at tip clearance of 0.1 mm for both the cases however minimum diffuser effectiveness is also observed at the same clearance level. Diffuser effectiveness is found to be maximum at zero gap for both cases. As it is practically impossible to have zero gap for unshrouded impellers so it is concluded that the optimum thickness is 0.5 mm onwards for mI and 0.5 mm for m2 in terms of diffuser effectiveness. mass averaged flow parameters, entropy, blade loading diagram and relative pressure fields are presented, showing the loss production within the impeller passage with tip clearance.

关键词： Centrifugal impeller Diffuser Stage Tip clearance Numerical simulation Entropy

Optimizing the Preparation Parameters of Nanocrystalline Zirconia for Catalytic Applications

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Acta metallurgica Sinica(English Letters) 2013年第5期26卷 565-573页

作者： m.m.Abd El-Latif m.S.Showman A.m.ibrahim m.m.Soliman Fabrication Technology Department Advanced Technology and New Materials Research Institute(ATNMRI) City of Scientific Research and Technological Applications (SRTA-City) Dharyya Colleges for Science and Atrs Qassim University Surface Chemistry and Catalysis Laboratory Physical Chemistry Department National Research Center Department of materials Science Institute of Graduate Studies and Research Alexandria University

Nanocrystalline zirconia powder with high surface area and high tetragonal phase percentage is prepared by the precipitation method using ammonium hydroxide as a precipitating agent. The pH of precipitation, preparation temperature and calcinations＇ temperature are *** size, specific surface area, tetragonal phase percentage and the thermal stability of the prepared samples are identified by diferent characterization tools such as X-ray difraction（XRD）, thermo gravimetric analysis（TGA）, diferential scanning calorimetry（DSC）, BET surface area, scanning electron microscopy（SEm） and transmission electron microscopy（TEm）. The optimum preparation parameters for obtaining nanocrystalline zirconia with high percentage of tetragonal phase and high surface area are pH 9, preparation temperature of 80℃ and calcinations＇ temperature of 400℃. The sample prepared under optimized conditions showed a high specific surface area of 179.2 m2/g, high tetragonal phase percentage of 81% and high catalytic activity（60%） for synthesis of butyl acetate ester.

关键词： Tetragonal zirconia Nanocrystalline zirconia Precipitation synthesis Catalytic properties of zirconia Esterification with zirconia

An efficient permutation approach for SbPN-based symmetric block ciphers

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Cybersecurity 2024年第2期7卷 113-130页

作者： mir Nazish m.Tariq Banday Insha syed Sheena Banday Department of Electronics and Instrumentation Technology University ofKashmirSrinagar 190006India

It is challenging to devise lightweight cryptographic primitives efficient in both hardware and software that can provide an optimum level of security to diverse Internet of Things applications running on low-end constrained ***,an effcient hardware design approach that requires some specific hardware resource may not be effcient if implemented in *** bit Permutation Network based ciphers such as PRESENT and GIFT are effcient,lightweight cryptographic hardware design *** ciphers introduce confusion and diffu-sion by employing a 4×4 static substitution box and bit *** bit-wise permutation is realised by sim-ple rerouting,which is most cost-effective to implement in hardware,resulting in negligible power ***,this method is highly resource-consuming in software,particularly for large block-sized ciphers,with each single-bit permutation requiring multiple *** paper proposes a novel software-based design approach for permutation operation in Substitution bit Permutation Network based ciphers using a bit-banding *** conventional permutation using bit rotation and the proposed approach have been implemented,analysed and compared for GIFT and PRESENT ciphers on ARm Cortex-m3-based LPC1768 development platform with KEIL mDK used as an Integrated Development *** real-time performance comparison between conven-tional and the proposed approaches in terms of memory(RAm/ROm)footprint,power,energy and execution time has been carried out using ULINKpro and ULINKplus debug adapters for various code and speed optimisation *** proposed approach substantially reduces execution time,energy and power consumption for both PRE-SENT and GIFT ciphers,thus demonstrating the effciency of the proposed method for Substitution bit Permutation Network based symmetric block ciphers.

关键词： Lightweight cryptography PRESENT GIFT SbPN Cortex-m LPC1768 Bit-band memory

Characterization and separation of pyrite from Abu Tartur black shale

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International Journal of mining Science and Technology 2015年第4期25卷 565-571页

作者： ibrahim S.S. El Kammar A.m. Guda A.m. Central metallurgical R&D Institute CMRDI Geology Dept. Faculty of Science National Research Astronomical & Geophysical Institute NRIAG

This work aimed for pyrite separation from Abu Tartur black shale as a source of sulfur to be an added economic value of Abu Tartur area. The considered samples in the present work were collected from a core drilled in Abu Tartur plateau representing the pyrite-rich black shale of the U. Cretaceous age, Sample characterization was carried out using petrographic microscope, XRD, DTA/DTG, C/S and XRF techniques. Clay minerals, silt-sized quartz, calcite, and hematite were the main minerals associating pyr- ite （5.34g）. Liberation behavior of the sample was about 80% below 5 μm. Sample processing was achieved through one-day soaking followed by classification using I inch mozley hydro-cyclone where about 35.5% by weight went to underflow and 64.5% went to overflow. The underflow product was subjected to an advanced gravity separation process using SB-40 Falcon Concentrator through a CCD statistical design prepared by Design-Expert 6.0 software proposed to opti- mize the separation process through a study for the effects of frequency （Hz） and water pressure （Psi） on both assay and recovery of the sulfur-rich heavy fraction. A heavy concentrate weighed 10.90% with inorganic sulfur content reached 11.37% （21.24% pyrite） with overall recovery （50.01%） was obtained after two cleaning at the optimum conditions.

关键词： Abu Tartur plateau Black shale Pyrite Falcon Concentrator

HLR-Net: A Hybrid Lip-Reading model Based on Deep Convolutional Neural Networks

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Computers, materials & Continua 2021年第8期68卷 1531-1549页

作者： Amany m.Sarhan Nada m.Elshennawy Dina m.ibrahim Department of Computers and Control Engineering Faculty of EngineeringTanta UniversityTanta37133Egypt Department of Information Technology College of ComputerQassim UniversityBuraydah51452Saudi Arabia

Lip reading is typically regarded as visually interpreting the speaker’s lip movements during the *** is a task of decoding the text from the speaker’s mouth *** paper proposes a lip-reading model that helps deaf people and persons with hearing problems to understand a speaker by capturing a video of the speaker and inputting it into the proposed model to obtain the corresponding *** deep learning technologies makes it easier for users to extract a large number of different features,which can then be converted to probabilities of letters to obtain accurate *** proposed methods for lip reading are based on sequence-to-sequence architectures that are designed for natural machine translation and audio speech ***,in this paper,a deep convolutional neural network model called the hybrid lip-reading(HLR-Net)model is developed for lip reading from a *** proposed model includes three stages,namely,preprocessing,encoder,and decoder stages,which produce the output *** inception,gradient,and bidirectional GRU layers are used to build the encoder,and the attention,fully-connected,activation function layers are used to build the decoder,which performs the connectionist temporal classification(CTC).In comparison with the three recent models,namely,the LipNet model,the lip-reading model with cascaded attention(LCANet),and attention-CTC(A-ACA)model,on the GRID corpus dataset,the proposed HLR-Net model can achieve significant improvements,achieving the CER of 4.9%,WER of 9.7%,and Bleu score of 92%in the case of unseen speakers,and the CER of 1.4%,WER of 3.3%,and Bleu score of 99%in the case of overlapped speakers.

关键词： lip-reading visual speech recognition deep neural network connectionist temporal classification

multitarget therapeutic strategies for Alzheimer's disease

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Neural Regeneration Research 2019年第3期14卷 437-440页

作者： mostafa m.ibrahim moustafa T.Gabr Department of Pharmacognosy Faculty of Pharmacy Mansoura University Department of Basic Pharmaceutical and Toxicological Sciences College of Pharmacy University of Louisiana at Monroe Department of medicinal Chemistry Faculty of Pharmacy Mansoura University Department of Chemistry University of Iowa

Neurodegenerative diseases such as Alzheimer's, Huntington's and Parkinson's diseases have multifaceted nature because of the different factors contributing to their progression. The complex nature of neurodegenerative diseases has developed a pressing need to design multitarget-directed ligands to address the complementary pathways involved in these diseases. The major enzyme targets for development of therapeutics for Alzheimer's disease are cholinesterase and β-secretase enzymes. In this review, we discuss recent advances in profiling single target inhibitors based on these enzymes to multitarget-directed ligands as potential therapeutics for this devastating disease. In addition, therapeutics based on iron chelation strategy are discussed as well.

关键词： multitarget-directed ligands acetylcholinesterase β-secretase Alzheimer's disease hybridization neurodegenerative diseases tacrine brain permeability

Numerical investigation on the heat transfer enhancement using a confined slot impinging jet with nanofluid

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Propulsion and Power Research 2019年第4期8卷 351-361页

作者： ibrahim K.Alabdaly m.A.Ahmed Department of mechanical Engineering College of EngineeringUniversity of AnbarRamadiAnbarIraq

In this article,laminar convective heat transfer of a confined slot impinging jet with nanofluid has been numerically investigated over Reynolds number ranges of *** circular ribs are mounted on the lower-target surface:one rib located right the stagnation point and another one located on the left of the stagnation ***2-water nanofluid with nanoparticles volume fraction ranging from 0 to 4%and nanoparticles diameters of 30 nm has been *** two-dimensional governing continuity,momentum and energy equations have been solved using finite volume method based on SImPLE *** effect of Reynolds number,nanoparticles volume fraction,rib height and rib location on the flow and thermal characteristics are presented and *** showed that the average Nusselt number,performance factor,total entropy generation as well as friction factor increase with increasing nanoparticles volume *** addition,it is found that the best thermal-hydraulic performance factor is around 1.89 which is obtained at Reynolds number of 1000,nanoparticles volume fraction of 4%,the rib height of 0.1 and the rib location of 2.

关键词： Jet impingement Nanofluid Entropy generation Thermal-hydraulic performance Finite volume method

Estimation of the Stress-Strength Reliability for Exponentiated Pareto Distribution Using median and Ranked Set Sampling methods

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Computers, materials & Continua 2020年第8期64卷 835-857页

作者： Amer ibrahim Al-Omari ibrahim m.Almanjahie Amal S.Hassan Heba F.Nagy Department of mathematics Faculty of ScienceAl al-Bayt UniversityMafraq25113Jordan Department of mathematics College of ScienceKing Khalid UniversityAbha62529Saudi Arabia Statistical Research and Studies Support Unit King Khalid UniversityAbha62529Saudi Arabia Faculty of Graduate Studies for Statistical Research Cairo UniversityGiza12613Egypt

In reliability analysis,the stress-strength model is often used to describe the life of a component which has a random strength(X)and is subjected to a random stress(Y).In this paper,we considered the problem of estimating the reliability𝑅𝑅=P[Ymaximum likelihood estimator of the stress strength reliability is calculated under simple random sample,ranked set sampling and median ranked set sampling *** different reliability estimators under median ranked set sampling are *** estimators are obtained when both strength and stress have an odd or an even set *** two other estimators are obtained when the strength has an odd size and the stress has an even set size and vice *** performances of the suggested estimators are compared with their competitors under simple random sample via a simulation *** simulation study revealed that the stress strength reliability estimates based on ranked set sampling and median ranked set sampling are more efficient than their competitors via simple random *** general,the stress strength reliability estimates based on median ranked set sampling are smaller than the corresponding estimates under ranked set sampling and simple random sample ***:Stress-Strength model,ranked set sampling,median ranked set sampling,maximum likelihood estimation,mean square *** estimates under ranked set sampling and simple random sample methods.

关键词： Stress-Strength model ranked set sampling median ranked set sampling maximum likelihood estimation mean square error

Power frequency AC voltage measurement based on double wound Rogowski coil

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High Voltage 2017年第2期2卷 129-135页

作者： mohamed E.ibrahim Amr m.Abd-Elhady High Voltage and Dielectric materials Lab. Faculty of EngineeringMenoufia UniversityShebin El_Kom 32511Egypt

This study presents a technique for power frequency AC voltage *** proposed technique utilises a capacitor having a low capacitance in addition to a double wound Rogowski *** technique depends on capacitor current measurement using the double wound Rogowski *** voltage across the capacitor that connected in parallel with the system at which AC voltage is intended to be measured is *** proposed technique is experimentally evaluated by designing the measurement system and using a digital signal processing board for the reconstruction ***,the experimental results based on Rogowski coil measurements are compared with those obtained from reference ***,the obtained results validate the efficacy of the proposed technique in power frequency AC voltage measurement.

关键词： Rogowski double capacitance