检索结果-南通市图书馆

Study of Sintering Behaviour and Electrical Conductivity of Cr-Zn-Fe-O System

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 1999年第1期15卷 79-82页

作者： Hanna, A.A. Khalil, m.Sh. saleh, H.i. Ali, A.F. inorganic Chemistry Department National Research Centre Dokki Cairo Egypt

A series of chemical composition based on Cr, Fe and O with Zn as a partially substituting ion has been prepared in the general formula Zn//xCr//1// minus //xFe//2O by coprecipitation method using NH//4OH as the precipitating agent at pH equals 10.3. The prepared samples were identified by both thermal analysis (DTA and TGA) and X-ray diffraction. it was found that no single phase is obtained for any of the studied compositions but a mixture of different phases is observed, depending on the molar percentage of zinc ion substitution as well as on the sintering temperature. The temperature dependence of the electrical conductivity, si.m. , of the prepared samples is plotted between 25 and 680 degree C. it was observed that the electrical conductivity increases with temperature for both samples with x equals 0.00 and 0.80 Zn ion content while it is nearly temperature independent for samples with intermediate Zn concentration x equals 0.2 and 0.5 mol fraction. The activation energy, E//a, calculated from the linear relation, lg si.m. -1000/T for the final mixtures (sintered at 1300 degree C) was calculated. (Edited author abstract) 16 Refs.

关键词： Chromi.m.compounds

A new distributed feature selection technique for classifying gene expression data

在线全文

学校读者我要写书评

暂无评论

international Journal of Bi.m.thematics 2019年第4期12卷 79-109页

作者： Sarah m.Ayyad Ahmed i.saleh Labib m.Labib Computers and Systems Department Faculty of Engineering Mansoura University Mansoura 35511 Egypt

Classification of gene expression data is a pivotal research area that plays a substantial role in diagnosis and prediction of diseases. Generally, feature selection is one of the extensively used techniques in data mining approaches, especially in classification. Gene expression data are usually composed of dozens of samples characterized by thousands of genes. This increases the dimensionality coupled with the existence of irrelevant and redundant features. Accordingly, the selection of informative genes (features) becomes difficult, which badly affects the gene classification accuracy. in this paper, we consider the feature selection for classifying gene expression microarray datasets. The goal is to detect the most possibly cancer-related genes in a distributed manner, which helps in effectively classifying the samples. initially, the available huge amount of considered features are subdivided and distributed among several processors. Then, a new filter selection method based on a fuzzy inference system is applied to each subset of the dataset. Finally, all the resulted features are ranked, then a wrapper-based selection method is applied. Experimental results showed that our proposed feature selection technique performs better than other techniques since it produces lower time latency and improves classification performance.

关键词： Feature selection gene expression dimensionality reduction microarray data classification distributed learning mathematics Subject Classification

The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt: Petrological and geochemical characteristics and mineralization

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 Journal Of Geochemistry 2006年第4期25卷 307-317页

作者： Gehad m. saleh Nuclear materials Authority P.O.Box: 530 El Maadi Cairo Egypt

The podiform chromitites occur in a well-preserved mantle sequence consisting of lherzolite-harzburgite with abundant lenses of olivine dunite. The podiform chromitite deposits are common as small and irregularly shaped masses in the Southeastern Desert (SED) of Egypt. The podiform chromitites exhibit a wide range of compositions from high Cr to high Al varieties. The Cr of chrome spinel ranges from 0.67 to 0.88 in olivine-dunite, quite similar to that of the high-Cr chromitite, whereas it is around 0.62 in lherzolite-harzburgite. Primary hydrous mineral inclusions, amphibole and phlogopite, in chrome spinel have been reported for the first time from the Pan-African Proterozoic podiform chromitites. On the other hand, petrographic and geochemical evidence suggests that podiform chromitites in the SED of Egypt were formed as a result of crystallization of mafic melts, probably of boninitic composition, the boninitic parental magmas were probably produced by a second stage of melting above a subduction zone. Three types of chromite ores can be distinguished within the SED of Egypt: (a) sulphide-poor podiform ores; (b) brecciated ores; and (c) sulphide-rich ores. Two textural types of inclusions in chromite are distinguished: (1) primary silicate inclusions generally have high mg-number (>96), Cr and Ni, and are dominated by pargasitic amphibole, forsterite, diopside, enstatite and Na-phlogopite. A diversity of primary and secondary platinum group minerals (PGm) is described from the chromitites, including alloys, sulphides, sulpharsenides and arsenides of Ru, Os, ir, Rh, Ni, Cu, Fe and Co; (2) in addition to primary PGm and hydrous silicates, the fluids are of low to moderate salinity, sodi.m.dominated aqueous solutions with complex gas contents. Variable amounts of water, hydrogen, hydrocarbons, carbon dioxides and nitrogen have been determined in inclusion-rich samples. The chondrite-normalized PGE patterns of lherzolite-harzburgite and olivine-dunite have negative

关键词：铬铁矿沉淀蛇绿岩复合物东南沙漠埃及岩石学

Geologic relationships and mineralization of peralkaline/alkaline granite-syenite of the Zargat Na’am ring complex, Southeastern Desert, Egypt

在线全文

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2006年第2期25卷 97-111页

作者： Gehad m. saleh Nuclear materials Authority P.O. Box: 530 EL Maadi Cairo Egypt

The Zargat Na’am ring complex crops out 90 km NW of Shalatin City in the Southeastern Desert of Egypt. The ring complex forms a prominent ridge standing high above the surrounding mafic-ultramafic hills. it is cut by two sets of joints and faults which strike predominantly NNW-SSE and E-W, and is injected by dikes, porphyritic alkaline syenites, and felsite porphyries. it consists of alkali syenites, alkali quartz syenites, and peralkaline arfvedsonite-bearing granitic and pegmatitic dikes and sills. The complex is characterized locally by extreme enrichments in REEs, wolframite and rare, high field strength metals (HFSm), such as Zr and Nb. The highest concentrations ({1.5} wt% Zr, {0.25} wt% Nb, {0.6} wt% ∑REEs) occur in aegirine-albite aplites that formed around arfvedsonite pegmatites. Quartz-hosted melt inclusions in arfvedsonite granite and pegmatite provide unequivocal evidence that the peralkaline compositions and rare metal enrichments are primary magmatic features. Glass inclusions in quartz crystals also have high concentrations of incompatible trace elements including Nb (750×10+{-6}), Zr (2500×10+{-6}) and REEs (1450×10+{-6}). The REEs, Nb and Zr compositions of the aegirine-albite aplites plot along the same linear enrichment trends as the melt inclusions, and Y/Ho ratios mostly display unfractionated, near-chondritic values. The chemical and textural features of the aegirine-albite aplites are apparently resultant from rapid crystallization after volatile loss from a residual peralkaline granitic melt similar in composition to the melt inclusions.

关键词：花岗岩埃及矿化作用地质条件

Geology and rare-earth element geochemistry of highly evolved, molybdenite-bearing granitic plutons, Southeastern Desert, Egypt

在线全文

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2007年第4期26卷 333-344页

作者： Gehad m. saleh Nuclear materials Authority P.O.Box: 530 El Maadi Egypt

The field relations, mineralogy, and major and trace elements (including REE analyses of whole-rock samples and minerals) of granites and their associated molybdenite + urani.m.mineralized aplites in Southeastern Desert, Egypt, have been studied. The granites are leucocratic and mostly peraluminous in nature with muscovite increasing at the expense of biotite. The chemical and mineralogical characteristics of the granitic rocks indicate that their melts originated from the LiLE-enriched mantle wedge by partial melting and are contaminated by crustal melts, followed by thermogravitational processes. Leucogranites with higher Na2O/K2O ratios from Um Dargag and Um maiat crystallized under H2O-saturated equilibri.m.conditions in which the exsolved vapor continuously migrated away. The REE patterns of the granites studied are characterized by LREE enrichments and negative Eu anomalies. in comparison, the potassic aplites and the more sodic leucogranites are depleted in LREE, enriched in HREE and show more remarkable negative Eu anomalies. Allanite and monazite are the most important REE carriers in the granites. These minerals are strongly enriched in LREE, whereas fluorite and xenotime, which are more abundant in the aplites, are enriched in HREE. The average Lu/Ce ratio represents the fractionation trend with respect to HREE. it is 0.71 for radioactive fluorite, and it increases to 1.22 for non-radioactive fluorite. The high REE contents of molybdenite represent re-deposition of the mobilized mo and REE. Due to the strong control of accessory minerals, the REEs are of limited use in petrogenetic modelling of highly evolved granitic systems.

关键词：辉钼矿稀土资源褐帘石独居石西南地区沙漠地带埃及

Rare metal-bearing pegmatites from the Southeastern Desert of Egypt:Geology,geochemical characteristics,and petrogenesis

在线全文

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2007年第1期26卷 8-22页

作者： Gehad m.saleh Nuclear materials Authority P.O.Box:530 El-MaadiCairoEgypt

The pegmatite province of the Southeastern Desert (SED) is part of a pegmatite district that extends from Egypt (extends to 1200 km2). Rare metal pegmatites are divided into (1) unzoned, Sn-mineralized; (2) zoned Li, Nb, Ta and Be-bearing; and (3) pegmatites and pegmatites containing colored, gem-quality tourmaline. The Rb/Sr data reflect a crustal origin for the rare metal pegmatites and indicate that the original SED magma was generated during the peak of regional metamorphi.m.and predates the intrusion of post-tectonic leucogranites. These bodies developed an early border zone consisting of coarse to very coarse muscovite+quartz+alkali feldspar, followed by an intermediate zone of dominant quartz+feldspar+muscovite rock. Garnet, tourmaline, beryl, galena, pyrite, amblygonite, apatite and monazite are rare accessories in both zones. Cassiterite tends to concentrate in replacement zones and along fractures in albite+quartz+muscovite-rich portions. The highest concentrations of cassiterite occur in irregular greisenized zones which consist dominantly of micaceous aggregates of green Li-rich muscovite, quartz, albite and coarse-grained cassiterite. The different metasomatic post-solidification alterations include sodic and potassic metasomati.m. greisenization and tourmalinization. Geochemically, the pegmatite-generating granites have a metaluminous composition, showing a differentiation trend from coarse-grained, unfractionated plagioclase-rich granite towards highly fractionated fine- to medi.m.grained, local albite-rich rock. Economically important ore minerals introduced by volatile-rich, rare metal-bearing fluids, either primarily or during the breakdown of the primary mineral assemblages, are niobi.m.tantalum oxides, Sn-oxides (cassiterite), Li-silicates (petalite, spodumene, euctyptite, and pollucite), Li-phosphates (amblygonite, montebrasite and lithopilite) and minor REE-minerals (Hf-zircon, monazite, xenotime, thorian, loparite and yttrio-fluorite). The pol

关键词：埃及东南部沙漠稀有金属伟晶岩地质地球化学特征岩石成因

URANi.m.miNERALiZATiON iN THE mUSCOViTE-RiCH GRANiTES OF THE SHALATiN REGiON, SOUTHEASTERN DESERT, EGYPT

在线全文

学校读者我要写书评

暂无评论

Chinese Journal Of Geochemistry 2006年第1期25卷 1-15页

作者： GEHAD m. saleh NUCLEAR mATERiALS AUTHORiTY P.O.BOX: 530 EL MAADI CAIRO EGYPT

The younger granitoids of the Shalatin district in the Southeastern Desert of Egypt, are of biotite and two-mica granite compositions. The geochemistry of rare-earth elements (REE), yttri.m. thori.m.and urani.m.forms the basis for many important methods to reconstruct igneous petrogenesis. Since the recognition that REE, Y, Th, U-rich accessories may play an important role in controlling the geochemistry of crustal melts, a considerable amount of work has been done in an attempt to understand their effects. However, this effort has been almost exclusively focused on three minerals: zircon, monazite and apatite. Nevertheless, the variety of REE-Th-U-rich accessories in granite rocks are neither limited to these three minerals nor are they always the main REE, Y, Th carriers. The geochemistry of REE, Y, Th and U reflects the behavior of accessories and some key major minerals such as garnet and feldspars, and may therefore give valuable information about the conditions of partial melting, melt segregation and crystallization of granite magmas in different crustal regimes. The geochemistry of U and Th during magmatic differentiation has been studied in many granites from different areas and it has been known that the U and Th contents of granitic rocks generally increase during differentiation, although in some cases they decrease. The Th/U ratio can either increase or decrease, depending on redox conditions, the volatile content or alteration by endogene or supergene solutions. The accessory assemblage of muscovite-rich granites and high-grade rocks is composed of monazite, xenotime, apatite, Th-orthosilicate, secondary U-mineralization and betafite-pyrochlore. REE, Y, Th and U are not suitable for geochemical modeling of granitoids by means of equilibri.m.based trace element fractionation equations, but are still useful petrogenetic tools.

关键词：铀矿化作用稀土元素花岗岩沙漠埃及

Blockchain for secure and decentralized artificial intelligence in cybersecurity: A comprehensive review

在线全文

学校读者我要写书评

暂无评论

Blockchain(Research and Applications) 2024年第3期5卷 184-208页

作者： Ahmed m.Shamsan saleh Department of information Technology University of TabukTabuk47512Saudi Arabia

As the use of artificial intelligence (Ai) grows within the field of cybersecurity, so does the demand for secure and decentralized Ai systems to protect against potential cyber threats. Blockchain technology has emerged as the ideal approach for increasing both the security and privacy of Ai systems since it provides decentralized and i.m.table data storage. This systematic literature review focuses on the integration of blockchain technology with decentralized Ai within cybersecurity. it provides a comprehensive taxonomy of blockchain technology and decentralized Ai for cybersecurity, serving as the starting point for the study. This paper begins with an overview of blockchain technology and its possible uses in cybersecurity and also analyzes its challenges and opportunities. Decentralized Ai is also covered in the study, along with its potential advantages and difficulties in decentralized Ai cybersecurity. Building on that foundation, this study provides convincing findings highlighting the beneficial relationships between blockchain technology and decentralized Ai for cybersecurity, contributing to a nuanced comprehension of their integration. moreover, it offers real-world uses of blockchain-enabled, decentralized Ai to discuss its usefulness in tackling cybersecurity concerns. Finally, this paper discusses future research directions for blockchain-enabled decentralized Ai in cybersecurity, including potential applications and implications of this technology in the field, emphasizing the potential of blockchain-enabled decentralized Ai in cybersecurity to enhance security, privacy, and trust in Ai systems.

关键词： Blockchain Artificial intelligence Decentralized Cybersecurity

Simplified mathematical model of proton exchange membrane fuel cell based on horizon fuel cell stack

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 modern Power Systems and Clean Energy 2016年第4期4卷 668-679页

作者： ibrahim m.m.saleh Rashid ALi Hongwei ZHANG materials and Engineering Research institute Sheffield Hallam UniversitySheffieldUK

This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane(PEm)fuel cell stack of 1 k *** model incorporates major electric and thermodynamic variables and parameters involved in the operation of the PEm fuel cell under different operational *** of each of these parameters and variables upon the operation and the performance of the PEm fuel cell are *** mathematical equations are modeled by using matlab-Simulink tools in order to simulate the operation of the developed model with a commercial available 1kW horizon PEm fuel cell stack(H-1000),which is used for the purposes of model validation and tuning of the developed *** model can be extrapolated to higher wattage fuel cells of similar *** equation is presented to determine the impact of using air to supply the PEm fuel cell instead of pure oxygen upon the concentration losses and the output voltage when useful current is drawn from it.

关键词： Proton exchange membrane(PEm)fuel cell Activation losses Ohmic losses Concentration losses Cathode-anode model membrane hydration model