检索结果-南通市图书馆

Impact of Drain Effluent on Surficial Sediments in the Mediterranean Coastal Wetland: Sedimentological Characteristics and Metal Pollution Status at Lake Manzala, Egypt

在线全文

学校读者我要写书评

暂无评论

Journal of Ocean University of China 2019年第4期18卷 834-848页

作者： FARHAT hassan I. Geology Department Faculty of Science Suez University

Surface sediments were collected from Lake Manzala, the Mediterranean coastal wetland located to the east of the Nile Delta, Egypt, to assess the effect of drain effluent on the spatial variations of sedimentary characteristics and heavy metal pollution. Grain-size compositions, textures, and heavy metal distribution patterns in sediments are presented using GIS technique. Results of the analysis of the sediment showed a clear effect of drain effluent, with an increase in fine fractions and homogeneous suspensions in transportation mode. Lake sediments were dominated by sandy mud textures, and mode of transportation was homogeneous sus- pension and rolling. Spatial distribution of heavy metals (Fe, Mn, Zn, Cu, Ni, Cr, and Pb) was studied in the lake’s surficial sediments, along with their relationship to drain effluent and their contamination status in the ecological system. Heavy metal pollution status was assessed by means of accepted sediment quality guidelines and contamination assessment methods (contamination factor, con- tamination degree, modified contamination degree, geo-accumulation, and enrichment factor). Among the determined heavy metals, Pb had the most ecological risk. Generally, the heavy metals in the surface sediments indicated pollution risk ranging from moderate to considerable, particularly, in those sites facing drains and inlets that had the highest toxic effluent. The results were interpreted by statistical means. A cluster analysis defined areas facing drain discharge and inlets as separated groups. ANOVA indicated that most of the sedimentation and studied metals directed this clustering.

关键词： Lake Manzala Mediterranean wetland metal pollution sedimentological characteristics

On Generalized Douglas–Weyl(α, β)-Metrics

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2015年第10期31卷 1611-1620页

作者： Akbar TAYEBI hassan SADEGHI Department of Mathematics Faculty of Science University of Qom

In this paper, we study generalized Douglas-Weyl （α,β）-metrics. Suppose that a regular （α,β）-metric F is not of Randers type. We prove that F is a generalized Douglas-Weyl metric with vanishing S-curvature if and only if it is a Berwald metric. Moreover, by ignoring the regularity, if F is not a Berwald metric, then we find a family of almost regular Finsler metrics which is not Douglas nor Weyl. As its application, we show that generalized Douglas-Weyl square metric or Matsumoto metric with isotropic mean Berwald curvature are Berwald metrics.

关键词： Generalized Douglas Weyl metric Weyl metric Douglas metric S-curvature

SOME RESULTS ON CONTROLLED FRAMES IN HILBERT SPACES

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2016年第3期36卷 655-665页

作者： Kamran MUSAZADEH hassan KHANDANI Department of Mathematics College of ScienceMahabad BranchIslamic Azad University

We use two appropriate bounded invertible operators to define a controlled frame with optimal frame bounds. We characterize those operators that produces Parseval controlled frames also we state a way to construct nearly Parseval controlled frames. We intro- duce a new perturbation of controlled frames to obtain new frames from a given one. Also we reduce the distance of frames by appropriate operators and produce nearly dual frames from two given frames which are not dual frames for each other.

关键词： frames Parseval frames dual frames controlled frames reconstruction formula perturbation

Composition Dependence of Surface Phonon Polariton Mode in Wurtzite InxGa1-xN （0 ≤ x ≤ 1） Ternary Alloy

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2008年第12期25卷 4378-4380页

作者： S. S. Ng Z. hassan H. Abu hassan Nano-Optoelectronics Research and Technology Laboratory School of Physics Universiti Sains Malaysia 11800 Minden Pulau Pinang Malaysia

We present a theoretical study on the composition dependence of the surface phonon polariton （SPP） mode in wurtzite structure α-InxGa1-xN ternary alloy over the whole composition range. The SPP modes are obtained by the theoretical simulations by means of an anisotropy model. The results reveal that the SPP mode of α-InxGa1-xN semiconductors exhibits one-mode behaviour. From these data, composition dependence of the SPP mode with bowing parameter of-28.9 cm^-1 is theoretically obtained.

关键词： field emission molybdenum dioxide enhancement factor

Statistical Inference of Chen Distribution Based on Two Progressive Type-II Censoring Schemes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第3期66卷 2797-2814页

作者： hassan M.Aljohani Department of Mathematics&Statistics Faculty of ScienceTaif UniversityTaif21944Saudi Arabia

An inverse problemin practical scientific investigations is the process of computing unknown parameters from a set of observations where the observations are only recorded indirectly,such as monitoring and controlling quality in industrial process *** regression can be thought of as linear inverse *** other words,the procedure of unknown estimation parameters can be expressed as an inverse ***,maximum likelihood provides an unstable solution,and the problembecomes more complicated if unknown parameters are estimated from different ***,researchers search for better *** study two joint censoring schemes for lifetime products in industrial process *** practice,this type of data can be collected in fields such as the medical industry and industrial *** this study,statistical inference for the Chen lifetime products is considered and analyzed to estimate underlying *** likelihood and Bayes’rule are both studied for model *** asymptotic distribution of maximumlikelihood estimators and the empirical distributions obtained withMarkov chainMonte Carlo algorithms are utilized to build the interval *** results using tables and figures are adopted through simulation studies and verified in an analysis of the lifetime *** briefly describe the performance of developed methods.

关键词： Chen distributions progressive type-II censoring maximum likelihood mean posterior Bayesian estimation MCMC

Simulation of quantum-well slipping effect on optical bandwidth in transistor laser

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Optics Letters 2009年第5期7卷 435-436页

作者： hassan Kaatuzian Seyed Iman Taghavi Photonics Research Laboratory Electrical Engineering DepartmentAmirkabir University of Technology

An optical bandwidth analysis of a quantum-well （16 nm） transistor laser with 150-μm cavity length using a charge control model is reported in order to modify the quantum-well location through the base region. At constant bias current, the simulation shows significant enhancement in optical bandwidth due to moving the quantum well in the direction of collector-base junction. No remarkable resonance peak, limiting factor in laser diodes, is observed during this modification in transistor laser structure. The method can be utilized for transistor laser structure design.

关键词： well Simulation of quantum-well slipping effect on optical bandwidth in transistor laser

Assessment of liquefaction potential based on shear wave velocity:Strain energy approach

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3733-3745页

作者： Mohammad hassan Baziar Mahdi Alibolandi School of Civil Engineering Iran University of Science and TechnologyTehran16846-13114Iran

Liquefaction assessment based on strain energy is significantly superior to conventional stress-based *** main purpose of the present study is to investigate the correlation between shear wave velocity and strain energy capacity of silty *** dissipated energy until liquefaction occurs was calculated by analyzing the results of three series of comprehensive cyclic direct simple shear and triaxial tests on Ottawa F65,Nevada,and Firoozkuh sands with varying silt content by weight and relative ***,the shear wave velocity of each series was obtained using bender element or resonant column ***,for the first time,a liquefaction triggering criterion,relating to effective overburden normalized liquefaction capacity energy(WL=s’c)to effective overburden stresscorrected shear wave velocity(eVs1)has been *** accuracy of the proposed criteria was evaluated using in situ *** results confirm the ability of shear wave velocity as a distinguishing parameter for separating liquefied and non-liquefied soils when it is calculated against liquefaction capacity energy(WL=s’c).However,the proposed WL=s’c-Vs1 curve,similar to previously proposed cyclic resistance ratio(CRR)-Vs1 relationships,should be used conservatively for fields vulnerable to liquefaction-induced lateral spreading.

关键词： Liquefaction Strain energy capacity Shear wave velocity Cyclic triaxial test Cyclic direct simple shear test Resonant column test Bender element test

Effect of Bainite Morphology on Mechanical Properties of the Mixed Bainite-martensite Microstructure in D6AC Steel

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第4期28卷 336-342页

作者： Khodamorad Abbaszadeh hassan Saghafian Shahram Kheirandish School of Metallurgy and Materials Engineering Iran University of Science and Technology Tehran *** Iran

The effect of bainite morphology on mechanical properties of the mixed bainite-martensite microstructure in D6AC low alloy ultra-high strength steel has been studied in the present work. For this purpose, samples austenitized at 910℃ for 40 min were quenched in three different ways. Some of the samples were directly oil-quenched, some others were quenched in salt bath at 330 ℃ and the remaining samples were quenched in salt bath at 425 ℃ for various holding times. All samples were tempered at 200 ℃ for 2 h. Microstructures were examined by optical microscopy （OM） and scanning electron microscopy （SEM）. Fracture surfaces also were studied by SEM. Results showed that the mixed microstructure containing martensite and 28 vol.% of the lower bainite exhibited higher yield and tensile strengths than the fully martensitic microstructure. This could be mainly attributed to the partitioning of the prior austenite grains by the lower bainite and enhancing the strength of lower bainite in the mixed microstructure by plastic constraint. Charpy V-notch （CVN） impact energy and ductility were improved by increasing the volume fraction of the lower bainite. This is not the case about the mixed microstructure containing the upper bainite and martensite. As a result, the tensile and CVN impact properties of mixed upper bainite-martensite microstructure are lower than those of the fully martensitic microstructure. Finally, fractography studies showed cleavage fracture at the surface of CVN impact specimens with martensitic and upper bainitic microstructures confirming the tendency to brittle behavior.

关键词： Upper bainite Lower bainite Microstructure D6AC Mechanical properties

Regenerative energy management of electric drive based on Lyapunov stability theorem

在线全文

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2019年第2期7卷 321-328页

作者： Shahab SABZI Mehdi ASADI hassan MOGHBELI Department of Electrical Engineering Arak University of Technology

In recent years, urban rail systems have developed drastically. In these systems, when induction electrical machine suddenly brakes, a great package of energy is produced. This package of energy can be stored in energy storage devices such as battery, ultra-capacitor and flywheel. In this paper, an electrical topology is proposed to absorb regenerative braking energy and to store it in ultracapacitor and ***-capacitor can deliver the stored energy to DC grid and charge the battery for auxiliary applications such as lighting and cooling systems The proposed system is modeled based on large signal averaged modeling, which leads to the simplicity of calculations. The control system is based on Lyapunov stability theorem which guarantees system stability. Also, an energy management algorithm is proposed to control energy under braking and steady-state conditions. Finally,the simulation results validate the effectiveness of the proposed control and energy management system.

关键词： DC/DC converter Lyapunov stability Bidirectional converter Energy management system(EMS) Ultra-capacitor Battery Switching function