检索结果-南通市图书馆

维普期刊数据库

Fabrication and characterization of YVO_4:Eu^(3+) nanomaterials by the microwave technique

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2011年第12期29卷 1137-1141页

作者： tran Thu Huong Vu Duc Tu tran Kim Anh Le Thi Vinh Le Quoc Minh Institute of Materials Science Vietnamese Academy of Science and Technology University of Engineering and Technology National University Hanoi Departments of Chemistry Hanoi University of Mining and Geology

Fabrication and characterization of YVO4：Eu^3＋ nanophosphors prepared by microwave （MW） irradiation assisted soft template synthesis were reported. The effects of synthesis conditions such as different powers of MW irradiation, pH values and concentration of reac- tion materials on properties of nanophosphor were also investigated to obtain the controllable size, morphology and high luminescence efficiency. Morphology, crystalline structure, and optical properties were characterized by field emission scanning electron microscopy （FE-SEM）, X-ray diffraction （XRD） and fluorescence spectroscopy, respectively. The results showed that YVOa：Eu^3＋ nanophosphors were obtained by using diethyleneglycol （DEG） as soft template, with pH values in the range of 4 to 12, upon microwave irradiation from 300 to 900 W, at temperature of 80 ℃. The high fluorescent YVOa：Eu^3＋ nanocrystals obtained with size from 15 nm down to 8 nm are more effective to develop an ultrahigh sensitive fluorescent label for biomolecule, cell and tissue.

关键词： microwave synthesis method DEG soft template YVO4:Eu^3+ nanophosphor luminescence rare earths

维普期刊数据库

Highly active brookite TiO2-assisted photocatalytic degradation of dyes under the simulated solar-UVA radiation

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2019年第6期29卷 641-647页

作者： Huyen tran Thi Thuong Chi tran Thi Kim Liem Nguyen Quang Hendrik Kosslick Institute of Materials Science (IMS) Vietnam Academy of Science and Technology (VAST) University of Rostock Institute of Chemistry Department of Inorganic Chemistry

Brookite TiO2nanoparticles were synthesized by hydrothermal method and characterized by X-ray powder diffraction(XRD), diffuse reflectance UV–Visible spectroscopy(DRUV), and scanning electron microscopy(SEM). The obtained particles were spherical in shape with the diameter of about ～10 nm under the hydrothermal temperature of 175 °C. The photocatalytic performance of brookite was investigated in the photodegradation of dyes(rhodamine B and rose bengal) under UV-A radiation by low-power lamp. The activity of brookite and the photodegradation efficiency of dyes were estimated using a UV–Visible spectrophotometer and a total organic carbon(TOC) analyzer. Compared to anatase and rutile prepared by the similar synthesis procedure, brookite is highly active in terms of decolourization, aromatic ring opening, and mineralization.

关键词： Brookite Anatase Dye Photocatalytic degradation Decolourization Mineralization

Hybrid competitive Lotka–Volterra ecosystems with a hidden Markov chain

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Control and Decision 2014年第1期1卷 51-74页

作者： Ky tran George Yin Department of Mathematics Wayne State UniversityDetroitMIUSA

This work concerns Lotka–Volterra models that are formulated using stochastic differential equations with *** from the existing formulations,the Markov chain that models random environments is *** such partially observed systems,we use Wonham’s filter to estimate the Markov chain from the observable evolution of the population,and convert the original system to a completely observable *** then show that the positive solution of our model does not explode in finite time with probability *** properties including stochastic boundedness,finite moments,sample path continuity and large-time asymptotic behaviour are also ***,stochastic permanence,extinction and feedback controls are also investigated.

关键词： Lotka-Volterra model hidden Markov chain partially observed system

Monte Carlo simulation of a cone-beam CT system for lightweight casts

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

Radiation Detection Technology and Methods 2021年第4期5卷 504-512页

作者： Thuy Duong tran Ngoc Ha Bui Kim Tuan tran Ngoc Toan tran Department of Nuclear Engineering and Environmental Physics School of Engineering PhysicsHanoi University of Science and Technology01 Dai Co VietHai Ba TrungHanoiVietnam Vietnam Atomic Energy Institute 59 Ly Thuong KietHoan KiemHanoiVietnam

Cone-beam computed tomography(CBCT),a modern technique with many applications,is becoming increasingly important and essential in many areas of economics and *** equipment has been commercialized in both hardware and ***,having a device system suitable for a specific group of objects will be the *** work used Monte Carlo simulation to optimize the design of a Cone-beam Computed Tomography(CBCT)for lightweight and small-size *** affecting image quality such as radiation-source,flat-panel detector,and geometrical distance were *** results indicate that an X-ray generator with a focal spot size of 4×4µm^(2),high voltage of 240 kV,and a radiation intensity of 10^(13) photon/s with a flat panel CsI(Tl)detector of 0.3 mm thickness and a pixel size of 0.1–0.2 mm,is suitable for a CBCT to inspect small objects in *** Monte Carlo model was validated against experiments and to evaluate some characteristics of the existing system.

关键词： Cone-beam computed technology Monte Carlo simulation Lightweight casts in industry Applied radiation

Enhancement of water absorption capacity and compressibility of hydrogel sponges prepared from gelatin/chitosan matrix with different polyols

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

Progress in Natural Science:Materials International 2022年第1期32卷 54-62页

作者： Thi Sinh Vo tran Thi Bich Chau Vo Trung Tien tran Nhan Duy Pham School of Mechanical Engineering Sungkyunkwan University Department of Industrial Management Can Tho University Department of Chemistry Memorial University of Newfoundland

The hydrogel sponges have prepared successfully from gelatin/chitosan(GEL/CTS) matrix with different polyols basing on scanning electron microscopy(SEM) and Fourier-transform infrared spectroscopy(FTIR) analysis. The results indicate that the compressibility and thermal properties(thermal gravimetric analysis, TGA) were improved significantly with adding the different polyols [poly(vinyl alcohol)-PVA, and poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) – PEPEG] into GEL/CTS matrix. Specially, the as-prepared hydrogel sponges with superabsorbent behavior were also investigated with the attained water absorption capacity to 605 g gand 585 g gfor GCV＿1/1/0.3 and GCE＿1/1/0.3 sponges, respectively, as well as the excellent water absorption capacity in a wide range of p H and salt concentration. Hence, these studies demonstrated that the hydrogel sponges are concerned as potential and promising candidates to apply especially in the fields of biomedicine and hygiene.

关键词： Hydrogel sponges Absorbent Chitosan Polyols Gelatin Water absorption capacity

Organic dye removal and recycling performances of graphene oxide-coated biopolymer sponge

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2022年第5期32卷 634-642页

作者： Thi Sinh Vo tran Thi Bich Chau Vo School of Mechanical Engineering Sungkyunkwan University Department of Industrial Management Can Tho University

In this study, a biopolymer sponge(PS) with a crosslinked mixture of gelatin-chitosan-poly(vinyl alcohol) was dipped into graphene oxide(GO) solution to form a composite sponge(CS, GO-coated PS) by a combination of simple dip-coating and freeze-drying procedures, as a sponge-like adsorbent in organic dye removal *** morphological, chemical, crystalline, mechanical and thermal characterizations of the as-obtained sponges were further investigated for the possible changes in the structure of sponge-like adsorbent after coating the GO sheets on the 3D porous structure of PS. The results showed that the CS had possessed effectively organic dye removal performances comparing to the PS. In the adsorption, the Langmuir and pseudo-second-order models corresponding to a monolayer approach and a chemical adsorption were appropriated. The maximum adsorption capacity of Rhodamine B and Congo red reached 126.8 and 135.0 mg·g-1; and 145.6 and 148.6 mg·g-1corresponding onto the PS and CS. It indicates that the maximum adsorption capacity on the CS enhanced significantly comparing to those on the PS owing to the functional GO sheets coated in the 3D porous structure of PS, which leads to supplying further functional adsorption sides on the whole 3D porous structure of CS. Notably, the sponges-like adsorbents could be regenerated and used again without a remarkable decrease of dye removal ability occurred in 9 adsorbing–desorbing cycles. Therefore, the CS prepared in this study can become a potential adsorbent for actual applications because of non-toxic materials, proper structural features, low-cost material and operation, and reliable recyclability.

关键词： Graphene oxide Biopolymer sponge Organic dye Adsorption Dye removal Recyclability

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

“神”速高铁——感受中国时代脉动

孔子学院（中西文对照版） 2024年第1期 52-55页

作者：陈氏深孟烨(翻译) 不详

2019年,我还是越南河内大学中文系的大三学生,因热爱中国文化选择了中文专业,也因此格外关注中国的发展变化。高铁,被评为中国的“新四大发明”之一,也是最能体现中国制造、中国智慧的时代符号之一。中国有句古话,“百闻不如一见”,幸... 详细信息

2019年,我还是越南河内大学中文系的大三学生,因热爱中国文化选择了中文专业,也因此格外关注中国的发展变化。高铁,被评为中国的“新四大发明”之一,也是最能体现中国制造、中国智慧的时代符号之一。中国有句古话,“百闻不如一见”,幸运如我,在那年被学校选中,参加了中国大连外国语大学主办的夏令营活动,有机会亲身领略高铁的风采。

关键词：中文专业夏令营活动越南河内四大发明高铁大学中文系大连外国语大学大三学生

Performance Analysis of Mixed Amplify-and-Forward and Decode-and-Forward Protocol in Underlay Cognitive Networks

维普期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

China Communications 2016年第3期13卷 115-126页

作者： tran Trung Duy Hyung Yun Kong Department of Telecommunications Posts and Telecommunications Institute of Technology Department of Electrical Engineering University of Ulsan

In this paper, we propose and evaluate outage performance of a mixed amplify-and-forward(AF) and decode-and-forward(DF) relaying protocol in underlay cognitive radio. Different from the conventional AF and DF protocols, in the proposed protocol, a secondary source attempts to transmit its signal to a secondary destination with help of two secondary relays. One secondary relay always operates in AF mode, while the remaining one always operates in DF mode. Moreover, we also propose a relay selection method, which relies on the decoding status at the DF relay. For performance evaluation and comparison, we derive the exact and approximate closedform expressions of the outage probability for the proposed protocol over Rayleigh fading channel. Finally, we run Monte Carlo simulations to verify the derivations. Results presented that the proposed protocol obtains a diversity order of three and the outage performance of our scheme is between that of the conventional underlay DF protocol and that of the conventional underlay AF protocol.

关键词： underlay cognitive network cooperative communication outage probability mixed AF and DF protocols Rayleigh fading channel

维普期刊数据库

An Efficient Differential Evolution for Truss Sizing Optimization Using AdaBoost Classifier

在线全文

学校读者我要写书评

暂无评论

Computer Modeling in Engineering & Sciences 2023年第1期134卷 429-458页

作者： tran-Hieu Nguyen Anh-Tuan Vu Hanoi University of Civil Engineering Hanoi100000Vietnam

Design constraints verification is the most computationally expensive task in evolutionary structural optimization due to a large number of structural analyses thatmust be *** a surrogatemodel to approximate the behavior of structures instead of the exact structural analyses is a possible solution to tackle this ***,most existing surrogate models have been designed based on regression *** paper proposes a novel method,called CaDE,which adopts a machine learning classification technique for enhancing the performance of the Differential Evolution(DE)*** proposed method is separated into two *** the first optimization stage,the original DE is implemented as usual,but all individuals produced in this phase are stored as inputs of the training *** on design constraints verification,these individuals are labeled as“safe”or“unsafe”and their labels are saved as outputs of the training *** collecting enough data,an AdaBoost model is trained to evaluate the safety state of *** model is then used in the second stage to preliminarily assess new individuals,and unpromising ones are rejected without checking design *** method reduces unnecessary structural analyses,thereby shortens the optimization *** benchmark truss sizing optimization problems are solved using the proposed method to demonstrate its *** obtained results show that the CaDE finds good optimal designs with less structural analyses in comparison with the original DE and four other DE *** reduction rate of five examples ranges from 18 to over 50%.Moreover,the proposed method is applied to a real-size transmission tower design problem to exhibit its applicability in practice.

关键词： Structural optimization machine learning surrogate model differential evolution AdaBoost classifier