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Feng H.,Hebei North University | Yang Y.,Hebei North University | Zhang X.,Zhangjiakou Vocational and Technical College | Xu Y.,Hebei North University | Guan J.,Hebei North University
Superlattices and Microstructures | Year: 2015

We synthesized Sr2SiO4:Eu3+ phosphors with spherical morphology by a spray-drying process. The obtained samples were characterized by XRD, SEM, and spectrophotometer. The XRD results show that samples have good crystallinity after the heat-treatment at 1150 °C. The higher temperature has no obvious influence on the crystallinity and will destroy the spherical morphology. The SEM results show that the phosphors are microspheres with size in the range of 0.8-2.1 μm when they were heat treated at 1050°C and 1150°C. The excitation and emission spectra of the samples indicate that Eu3+ ions doped into Sr2SiO4 host successfully. The Sr2SiO4:Eu3+ sample heat-treated at 1150°C has the highest emission intensity and the longest decay times. The results of this work indicate that the optimized heat-treatment temperature should be at 1150°C for Sr2SiO4:Eu3+ micro-spherical phosphors synthesized by the spray-drying process. ©2014 Elsevier Ltd. All rights reserved.

Yang Y.,Hebei North University | Feng H.,Hebei North University | Zhang X.,Zhangjiakou Vocational and Technical College
Journal of Materials Science: Materials in Electronics | Year: 2014

NaY(WO4)2:(Ho3+, Yb3+) phosphors were synthesized by microwave heating in an EDTA-mediated process. The samples were characterized by XRD, FT-IR, SEM, and fluorescence spectrophotometer. The XRD and FT-IR results show that the samples have the tetragonal phase. The SEM results show that obtained samples have octahedral morphology. ‘Oriented attachment’ and ‘Ostwald ripening’ play key roles in the formation of octahedrons. The UC emission spectra of NaY(WO4)2:(Ho3+, Yb3+) phosphors under 980 nm excitation show two intense bands corresponding to 5F4 + 5S2 → 5I8 and 5F5 → 5I8 transitions of Ho3+ ions. Based on the energy level diagrams of Yb3+ and Ho3+, as well as the results of power dependence of UC emission intensities, possible excitation path ways for different bands are deduced. The green and red UC emissions of NaY(WO4)2:(Ho3+, Yb3+) phosphors originate from the two-photon process. Also, the samples have good thermal stability. © 2014, Springer Science+Business Media New York.

Xie B.Y.,Zhangjiakou Vocational and Technical College | Zhao D.C.,Hebei North University
Applied Mechanics and Materials | Year: 2013

Objective This paper investigates new Web-based course content in the Network environment, the role of curriculum evaluation and significance, the evaluation methods, processes, and should adhere to the principles of the network. [Process and methods] The process and methods are compared with the traditional environment through experimental research, theoretical research and system analysis combined with the digital network environment, access to experimental control with a combination of survey methods. [Results] It focuses on teaching content, learning resources and resides among the contents of teaching strategies and learning strategies of evaluation, involving students, teachers, learning materials, online teaching support systems, learning support and service system in each part. evaluation of online courses plays a guiding role in guiding the design and development of online courses in the right direction; By analyzing the course of learning resources, learning process and its causes, we can determine its effectiveness, shortcomings, contradictions and problems and find out the reasons, ways and measures for improvements. Can improve the network quality of the course and optimize teaching. [Conclusion] Online course teaching evaluation of network can provide reliable protection and guidance function, and it is a strong fulcrum in the whole systems engineering courses and online teaching. © (2013) Trans Tech Publications, Switzerland.

Xie B.Y.,Zhangjiakou Vocational and Technical College | Zhao D.C.,Hebei North University
Applied Mechanics and Materials | Year: 2013

Objective The research of digital games characteristics and connotations are to explore creating favorable conditions of independent study; to analyze the learning motivation, learning activities and process, self-confidence, aesthetic ability of students during the activities of the digital game, to learn the impact of creativity.[Methods] Simulation, experimental teaching, the comparison of experimental and traditional teaching methods are used. [Results] The experiments show that the vast majority of learners on the digital game for learners to create learning conditions and elements, as well as to develop learners' abilities and have made a positive evaluation (M = 4.059, SD = 0.732). Endorsement or in favor of digital games very much are to improve their capacity for cooperation and autonomy which accounted for 93.6% and 78.2% respectively; endorsement or in favor of such an environment favorable to learning accounted for 78.4%; that the learning environment for students to learn positive emotions accounted for 95.8%; 87.1% of the test that the environment to cultivate their sense of learning. [Conclusion] Digital game provides the independent study of effective resources, environment, elements, activities and processes, but also contains the self-motivation to learn; digital game activities contributed to enhancing learners' self-confidence, aesthetic skills, creativity, help to lead to a research study of the learners; an effective way of learning is the integration of learning and entertainment. © (2013) Trans Tech Publications, Switzerland.

Lan A.,Hebei North University | Li B.,Hebei North University | Shen H.,Zhangjiakou Vocational and Technical College | Zhang J.,Zhangjiakou Vocational and Technical College
Journal of Materials Science: Materials in Electronics | Year: 2015

We synthesized SrWO4:Ho3+, Yb3+, Tm3+ microspheres successfully by the solvothermal process. The samples were characterized by XRD, FTIR, SEM, and fluorescence spectrofluorometer. The XRD patterns and FTIR spectra indicate that the samples have the pure tetragonal scheelite structure. The SEM images suggest that Na-Citrate plays a key role in the formation of spherical morphology. The samples are microspheres if there is the use of Na-Citrate, whereas the samples are irregular particles if there isn’t the use of Na-Citrate. Under diode laser excitation of 980 nm, SrWO4:Ho3+, Yb3+, Tm3+ samples show blue, green, and red emissions originating from the transitions of Ho3+ and Tm3+ ions. The emission intensity of microspheres is about twice those of irregular particles. The emission shows clear dependence on pump powers. On the basis of the luminescence properties of SrWO4:Ho3+, Yb3+, Tm3+ phosphors, the possible mechanisms are speculated. © 2014, Springer Science+Business Media New York.

Zhao D.C.,Hebei North University | Xie B.Y.,Zhangjiakou Vocational and Technical college
Applied Mechanics and Materials | Year: 2013

Based on the knowledge management theory, social constructivist theory, the theory of team learning, object-oriented programming methods, from the student's learning characteristics and the technology platform and operating environment and etc., feasibility analysis and needs analysis are carried out. System design and development are becoming into the design goals of social, intelligence and humanity, the abstract factory design pattern to SQL Sever as a database service system are chosen to be used a number of key technologies, combined with intelligent, high-performance, full-featured search technology, efficient, general purpose, open-to-use Web-based course system are designed and developed. © (2013) Trans Tech Publications, Switzerland.

Liu Y.,Hebei North University | Lan A.,Hebei North University | Jin Y.,Zhangjiakou Vocational and Technical College | Chen G.,Hebei North University | Zhang X.,Hebei North University
Optical Materials | Year: 2015

Sr3Bi(PO4)3:Eu2+, Sr3Bi(PO4)3:Mn2+, and Sr3Bi(PO4)3:Eu2+, Mn2+ phosphors were synthesized by solid state reaction. The structure and luminescent characteristics were investigated by X-ray powder diffraction and fluorescent spectrophotometer. All samples have the structural type of eulytine. The excitation and emission spectra of Sr3Bi(PO4)3:0.01Eu2+ sample show characteristic bands of Eu2+ ions. Also, the excitation and emission spectra of Sr3Bi(PO4)3:0.06Mn2+ sample show characteristic bands of Mn2+ ions. The emission color of Sr3Bi(PO4)3:Eu2+, Mn2+ sample could be tuned through tuning the co-dopant concentration of Mn2+ ions. The decay times for the Eu2+ ions decrease with the increase of Mn2+ dopant concentration, but the energy transfer efficiency increases with the increase of Mn2+ dopant concentration. On the basis of the luminescent spectra and fluorescence decay curves, we confirm that the energy transfer process from the Eu2+ to Mn2+ ions takes place in the co-doped Sr3Bi(PO4)3 phosphor. Sr3Bi(PO4)3:Eu2+, Mn2+ sample shows the good thermostability. The emission intensity of the sample at 400 K is about 60% of the value at 300 K. These results show Sr3Bi(PO4)3:Eu2+, Mn2+ phosphors could be anticipated for UV-pumped white-light-emitting diodes. © 2014 Elsevier B.V. All rights reserved.

Liu Y.,Hebei North University | Ma Y.,Hebei North University | Jin Y.,Zhangjiakou Vocational and Technical College | Chen G.,Hebei North University | Zhang X.,Hebei North University
Journal of Electroanalytical Chemistry | Year: 2015

Heteroatom doping is an effective way to modulate the electronic structure and properties of graphene. Despite a growing interest in sulfur (S)-doped graphene (SG), synthesis of high-quality SG at low cost remains a great challenge. In this study, we developed a rapid, efficient and cost-effective microwave-assisted solvothermal (MAS) method for the preparation of SG. It was found that a short MAS time of 6 min could generate few-layer SG (0.5 μm in lateral size) having effective oxygen reduction, high level of S-doping, sole thiophene-S bonding configuration, and high electrical conductivity. Furthermore, the resulting SG could serve as an effective electrocatalyst for H2O2 reduction, showing improved electrocatalytic activity over its undoped counterpart and good sensing performances for highly sensitive and selective detection of H2O2, indicating that SG may be a promising candidate for electrochemical sensor applications. © 2014 Elsevier B.V. All rights reserved.

Zhao J.,Hebei University | Li J.,Hebei University | Hao J.,Hebei University | Ma Y.,Hebei University | Feng X.,Zhangjiakou Vocational and Technical College
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

There is a current problem that agricultural tools easily get worn and frequently lose effectiveness. In order to solve this problem, the TiCN/Fe metal ceramic coating had been successfully prepared on a Q235 steel specimen surface by a reaction nitrogen arc cladding technique with a TXII500 argon arc welding machine. In the coating preparation, the industrial titanium powder and the graphite powder (300 mesh, a purity of 98%) are mixed at the ratio of 47.9: 12 in weight with 6 hours through the DQM type planetary ball mill, and precoated on the specimen surface. The precoated thickness is 2±0.2 mm, and the industrial N2 (purity 99.999%) is used as a reaction and protection gas. The coating was prepared on the surface of a specimen based on the high temperature of the nitrogen arc which made the N2 and precoated powder react in the course of welding. Effects of cladding speed (1.5, 2.0, 3.0 mm/s) on morphology, phase, and microhardness of the TiCN/Fe coating were analyzed by means of a scanning electronic microscope (SEM), X-ray diffractometer (XRD), and microhardness gauge, and contrast tests of wear were done between agricultural tools and coating. The results showed that the surface of the coating can obtain good morphology when the cladding speed is 1.5 mm/s, but when the coating contains less TiCN and the microhardness of coating is low; with the increase of the cladding speed(such as 3.0 mm/s), the coating morphology is worse off, but the microhardness and wear resistance have been increased obviously. The microhardness on the coating surface could reach up to HV0.5 1089, about 3 times as much as Q235 microhardness. Contrasted with common agricultural tools material (65 Mn), the wear loss is only 1/2 times as 65Mn, and the coating wear resistance is better. The coating can be used on agricultural tools for improving the service life of tools.

He H.,Zhangjiakou Vocational and Technical College | Zhao P.,Shandong University | Yue Q.,Shandong University | Gao B.,Shandong University | And 2 more authors.
Renewable Energy | Year: 2015

The preparation and characteristics of a composite phase change material (PCM) produced by incorporating polynary fatty acid eutectic mixture into sludge ceramsite were studied. According to Schröeder-Van Laar equation, five different kinds of polynary fatty acid eutectic mixture were prepared, and one of them, suitable for regulating room temperature, was absorbed into sludge ceramsite by vacuum impregnation method. The microstructures were observed by scanning electron microscope (SEM). The thermal properties and chemical structures were analyzed by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectrometer, respectively. The durability or stability of the composite PCM was determined by heating-cooling cycles test, and the temperature regulation effect was tested by building models. The results indicated that polynary fatty acid eutectic mixture can be retained by 46wt.% into the pores of sludge ceramsite without seepage. The melting temperature of composite PCM was 26.66°C, and the corresponding melting enthalpy was 47.1J/g, suitable to regulate building room temperature. The preparation of composite PCM was just a physical combination, and its chemical structures can remain stable in application process. In addition, model experiments showed that the prepared composite PCM can significantly reduce indoor temperature fluctuation, suitable for building energy conservation. © 2014 Elsevier Ltd.

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