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Normal Impact of A Rigid Cone-shaped against A Viscoelastic Plate on Viscoelastic Foundation 粘弹性基础上刚性圆锥体对粘弹性板的法向冲击
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4661
Dương Tuan Manh
This paper considers the problem of a low-velocity normal impact of a rigid cone-shaped upon a viscoelastic plate. The contact force is defined by the modified Hertz's contact law. Approximate solutions of the system of nonlinear integro-differential equations for the contact force and local indentation have been obtained.  
本文研究粘弹性板上刚性圆锥的低速法向冲击问题。接触力由修正赫兹接触定律定义。得到了接触力和局部压痕非线性积分微分方程组的近似解。
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引用次数: 1
Linear and Nonlinear Magneto-optical Absorption Coefficients and Refractive Index Changes in Wse2 Monolayer Wse2单层膜线性和非线性磁光吸收系数和折射率的变化
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4629
Luong Van Tung, Nguyen Quang Bau, Tran Thi Ngoc Bich, Pham Tuan Vinh, Huynh Vinh Phuc
This work studies the linear, the third-order nonlinear, and the total optical absorption coefficients (OACs) and the refractive index changes (RICs) caused by both intra- and inter-band transitions in the WSe2 monolayer. The expression for the OACs and RICs in the presence of a magnetic field as well as the Zeeman and electric fields are found by using the compact density matrix approach. The results show that the spin states strongly affect the OACs and RICs, which display the violet-shift behavior with the increase of the magnetic field. The Zeeman fields do not affect the peak positions but slightly reduce peak intensities. The OACs and RICs due to intra-band transition display only one peak in the THz range, while the inter-band spectra show a series of peaks in the near-infrared optical range, making monolayer WSe2 be a promising candidate for novel optoelectronic applications.  
本文研究了WSe2单层中线性、三阶非线性、总光吸收系数(OACs)和折射率(RICs)在带内和带间跃迁引起的变化。利用紧致密度矩阵方法得到了在磁场、塞曼电场和电场存在下的oac和RICs的表达式。结果表明,自旋态对oac和RICs有强烈的影响,随磁场的增加,oac和RICs表现出紫移行为。塞曼场不影响峰的位置,但会略微降低峰的强度。由于带内跃迁导致的oac和RICs仅在太赫兹范围内显示一个峰,而带间光谱在近红外光学范围内显示一系列峰,使单层WSe2成为新型光电应用的有希望的候选者。
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引用次数: 0
Excess Conductivity Analyses in Bi-Pb-Sr-Ca-Cu-O Systems Sintered at Different Temperatures 不同温度烧结Bi-Pb-Sr-Ca-Cu-O体系的超导电性分析
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4602
Trần Tiến Dũng, P. An, Tran Ba Duong, N. K. Man, Nguyen Thi Minh Hien, Tran Hai Duc
This paper studies the effects of the sintering temperature on crystal structure, critical temperature (Tc) and excess conductivity of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) system. Bulk BPSCCO samples were fabricated by the solid-state reaction method. Four different temperatures of 835 °C, 840 °C, 845 °C, and 850 °C were applied to sinter four different samples. The crystal structure of the samples was investigated through X-ray diffraction measurements (XRD) and scanning electron microscopy (SEM). Superconductivity of the samples was analyzed by the temperature-dependent resistivity measurement. The experimental results showed the existence of both Bi-2223 and Bi-2212 phases in all samples. Quantitatively, the volume fraction of the Bi-2223 phase was found to increase from 53.56% to 75.97%, and the average grain size of Bi-2223 phase was observed to enlarge from 57.95 nm to 86.50 nm as the sintering temperature increased from 835 °C to 850 °C. In addition, the excess conductivity analyses based on the theory of Aslamazov - Larkin (AL) and Lawrence - Doniach (LD) showed decreases in the coherence lengths (ξc(0)) from 1.957 Å to 1.565 Å and the effective inter-layering spacing (d) from 79.7 Å to 64.5 Å. Meanwhile, the interlayer coupling strength (J) between two CuO2 planes was estimated to increase from 0.00083 to 0.00137. These results might be evidence to conclude that the increasing of the sintering temperature obviously improves the superconductivity in the BPSCCO system.    
本文研究了烧结温度对Bi-Pb-Sr-Ca-Cu-O (BPSCCO)体系晶体结构、临界温度(Tc)和超导电性的影响。采用固相反应法制备了BPSCCO样品。采用835°C、840°C、845°C、850°C四种不同温度对四种不同样品进行烧结。通过x射线衍射仪(XRD)和扫描电镜(SEM)研究了样品的晶体结构。通过温度相关电阻率测量分析了样品的超导性。实验结果表明,所有样品中均存在Bi-2223相和Bi-2212相。随着烧结温度从835℃升高到850℃,Bi-2223相的体积分数从53.56%增加到75.97%,Bi-2223相的平均晶粒尺寸从57.95 nm增大到86.50 nm。此外,基于Aslamazov - Larkin (AL)和Lawrence - Doniach (LD)理论的过量电导率分析表明,相干长度(ξc(0))从1.957 Å减小到1.565 Å,有效层间间距(d)从79.7 Å减小到64.5 Å。同时,两个CuO2平面间的层间耦合强度(J)由0.00083增加到0.00137。这些结果表明,烧结温度的升高明显改善了BPSCCO体系的超导性。
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引用次数: 0
Effective Couplings between Two Photons and Axion in the 3-3-1 Model 3-3-1模型中双光子与轴子的有效耦合
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4627
Hoang Ngoc Long, Vo Van Vien, Vu Hoa Binh
The one-loop contribution axion-photon-photon coupling is presented in the framework of the 3-3-1 model, in which the loop diagrams are finite. The decay of axion into two photons is demonstrated. This study shows that it is easy to fulfill dark matter candidate conditions for the axion in the model.  
在3-3-1模型框架下给出了轴-光子-光子耦合的单回路贡献,其中环路图是有限的。证明了轴子衰变为两个光子。该研究表明,模型中轴子很容易满足暗物质的候选条件。
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引用次数: 0
Enhanced Photocatalytic Activity Using Near Visible Light of ZnO Nanorods by Doping with Mn2+ Ions 在近可见光下掺杂Mn2+离子增强ZnO纳米棒的光催化活性
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4626
Luong Hoai Nhon, Nguyen Huu Khoa, Lai Thi Ngoc Huyen, Huynh Hung Quang, Dinh Tan Muon, Nguyễn Hoàng Ngọc Phương, Tran Cong Khanh, Phan Bach Thang, Dang Vinh Quang
ZnO is a promising photocatalyst for photocatalytic oxidation of organic compounds under the influence of sunlight that provides clean energy and decomposes sustainable organic pollutants substances. ZnO is found to have non-toxic properties, long-term stability, high carrier mobility, low cost and biocompatibility. However, some disadvantages of ZnO limit its use in photocatalysis. Due to its wide bandgap, ZnO can only be activated under UV illumination. On the other hand, the photo-excited electron-hole pairs that recombine quickly on ZnO surface, suppress its photocatalytic properties. To improve its properties and performance, doping with transition metals was used to improve the optical properties of ZnO. Among the transition metal ions, Manganese (Mn) was commonly used to improve and tune the optical, electrical, diameter, height, and the number of nanorods (NRs) per unit area. Introduction of Mn into ZnO could enhance the photocatalytic activity due to the increase in the defect sites that effectively decreased the recombination of free electrons and holes. This study successfully synthesized ZnO nanorod arrays generated on glass substrates with different concentrations of doping Mn (0, 0.5, 1, 1.5 and 2%) at 100 °C by a simple hydrothermal method. To investigate the structure, morphology and optical properties, ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted. With the range of Mn doping ≤ 2% mol, the band gap reduced slightly, and the most optimized Mn doping concentration was of 0.5%. Overall, this work shows that the most effective way to increase ZnO’s photocatalytic activity in the visible region by reducing its band gap was the reduction in the size of the material or denaturation of ZnO by certain metals or non-metals.  
ZnO是一种很有前途的光催化剂,可以在阳光的作用下光催化氧化有机化合物,提供清洁能源并分解可持续的有机污染物物质。ZnO具有无毒、长期稳定、高载流子迁移率、低成本和生物相容性等特点。然而,ZnO的一些缺点限制了它在光催化中的应用。由于ZnO具有较宽的带隙,所以只能在紫外光照射下被激活。另一方面,光激发的电子-空穴对在ZnO表面快速重组,抑制了其光催化性能。为了改善ZnO的性质和性能,采用掺杂过渡金属的方法来改善ZnO的光学性能。在过渡金属离子中,锰(Mn)通常用于改善和调节单位面积纳米棒(NRs)的光学、电学、直径、高度和数量。在ZnO中引入Mn可以提高ZnO的光催化活性,这是由于缺陷位点的增加有效地减少了自由电子和空穴的复合。本研究通过简单的水热法,在100℃条件下,成功地在不同Mn掺杂浓度(0、0.5、1、1.5和2%)的玻璃基板上合成了ZnO纳米棒阵列。采用紫外可见光谱(UV-Vis)、x射线衍射(XRD)和扫描电子显微镜(SEM)对其结构、形貌和光学性能进行了研究。在Mn掺杂≤2% mol的范围内,带隙略有减小,Mn掺杂浓度为0.5%为最优。总的来说,这项工作表明,通过减小ZnO的带隙来提高ZnO在可见光区域的光催化活性的最有效方法是减小材料的尺寸或通过某些金属或非金属使ZnO变性。
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引用次数: 2
Free Vibration and Bending of Gradient Auxetic Plate Using Finite Element Method 梯度减振板的自由振动与弯曲有限元分析
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4664
Pham Hong Cong, Vu Dinh Tung, Do Duc Hai, Nguyen Dinh Khoa
In recent years, there has been a new approach to the material industry that uses sandwich structures with auxetic honeycomb cores with the interesting property of negative Poisson's ratios. In this paper, the Finite Element Method (in ANSYS) is used to investigate natural frequency of vibration and bending characteristics under varying pressure loads applied on the top skin when changing fundamental properties of some gradient configurations, including angular gradient, thickness gradient and functional gradient configurations of the auxetic plate with honeycomb structure. Thereby, the advantages of each configuration are investigated, studied, and obtained; therefore, it is expected to be applied in various industry sectors, such as wind turbine blades, aircraft wings, among others.  
近年来,在材料工业中出现了一种新的方法,即使用具有负泊松比的有趣性质的消声蜂窝芯夹层结构。本文采用有限元法(ANSYS)研究了蜂窝结构减振板在改变一些梯度配置(包括角梯度、厚度梯度和功能梯度配置)的基本特性时,顶蒙皮在不同压力载荷作用下的固有振动频率和弯曲特性。从而,调查、研究并获得每种结构的优点;因此,它有望应用于各种工业领域,如风力涡轮机叶片,飞机机翼等。
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引用次数: 0
Evaluation of Thick Target PIXE Analysis in the 5SDH-2 Pelletron Accelerator Facility at VNU University of Science VNU理学院5SDH-2颗粒加速器设备厚靶pixie分析评价
Pub Date : 2021-12-03 DOI: 10.25073/2588-1124/vnumap.4623
B. T. Hoa, N. T. Nghia, V. Phong, T. T. Anh
This paper presents the evaluation of the Thick Target Particle Induced X-rays Emission (TTPIXE) technique using standard samples. The element-dependent standardization factor, H, as a function of X-ray energies is calibrated using standard sample NIST-611 and validated with two standard samples: IAEA-Soil7 and NIES-Pepperbush. The obtained results are in good agreement with the reference data.  
本文用标准样品对厚靶粒子诱导x射线发射技术进行了评价。元素相关标准化因子H作为x射线能量的函数使用标准样品NIST-611进行校准,并使用两个标准样品:IAEA-Soil7和ies - pepperbush进行验证。所得结果与参考数据吻合较好。
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引用次数: 0
Photoluminescent Properties of Red-emitting AlPO4:Cr3+ Phosphor for Plant Growth LEDs 植物生长led用红发AlPO4:Cr3+荧光粉的光致发光特性
Pub Date : 2021-09-27 DOI: 10.25073/2588-1124/vnumap.4617
Tran Manh Trung, N. Tu, N. V. Quang, D. Q. Trung, P. T. Huy
In this study, red-emitting AlPO4:Cr3+ phosphors have been successfully synthesized by a facile sol-gel method. The Tanabe–Sugano diagram demonstrates that the surrounding sites of Cr3+ ions has a high crystal field with Dq/B=2.47. The sharp 694-nm peak on the PL of AlPO4:Cr3+ phosphor could be attributed to the 2E→4A2 electron transition of Cr3+ ions. The AlPO4:0.3%Cr3+ phosphor presents the highest PL intensity, then a purple LED prototype is obtained by coating the optimum powder on a UV LED chip. The color coordinates (0.2412, 0.1330) of the purple LED prototype implies that AlPO4:Cr3+ phosphors are promosing to be used as deep red phosphor powder for horticulture LED lighting.
本研究采用溶胶-凝胶法成功合成了AlPO4:Cr3+发红光荧光粉。Tanabe-Sugano图表明,Cr3+离子的周围位置具有高的晶体场,Dq/B=2.47。在AlPO4:Cr3+荧光粉的PL上出现694 nm的尖峰可以归因于Cr3+离子2E→4A2的电子跃迁。AlPO4:0.3%Cr3+荧光粉的发光强度最高,然后将最佳粉末涂覆在UV LED芯片上,得到了紫色LED原型。紫色LED原型的颜色坐标(0.2412,0.1330)表明AlPO4:Cr3+荧光粉有望作为深红色荧光粉用于园艺LED照明。
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引用次数: 0
CTAB-assisted Synthesis and Characterization of FePd Nanoparticles ctab辅助制备FePd纳米颗粒及其表征
Pub Date : 2021-09-20 DOI: 10.25073/2588-1124/vnumap.4669
N. Hoang Nam, Nguyen Thi Bich Ngoc, Truong THANH TRUNG, Tran Thi Hong, Phi Thi Huong, N. H. Luong
Fe50Pd50 nanoparticles with small size of around 5-9 nm were prepared by sonoelectrodeposition in the presence of cetyltrimethylammonium bromide (CTAB) surfactant. The as-prepared nanoparticles were annealed at 550oC for a series of times from 1 h to 6 h. After annealing a transformation from a disordered face-centered-cubic structure to the ordered L10 structure occurred. It was revealed that the coercivity of the nanoparticles is larger compared to that of the samples prepared by the same method in the absence of CTAB. The structural and magnetic properties of the samples were studied in dependence of annealing time. The results indicate a similar behavior of the evolution of tetragonality ratio and coercivity with annealing time in the nanoparticles.
以十六烷基三甲基溴化铵(CTAB)为表面活性剂,采用声电沉积法制备了Fe50Pd50纳米颗粒,粒径约为5 ~ 9 nm。将制备的纳米颗粒在550℃下进行1 ~ 6 h的连续退火,退火后由无序面心立方结构转变为有序的L10结构。结果表明,在不添加CTAB的情况下,纳米颗粒的矫顽力比用相同方法制备的样品大。研究了样品的结构和磁性能随退火时间的变化规律。结果表明,纳米颗粒的四方性比和矫顽力随退火时间的变化规律相似。
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引用次数: 1
Steady State Calculations of the PWR MOX/UO2 Core with the Monte Carlo Code MCNP6 基于蒙特卡罗代码MCNP6的压水堆MOX/UO2堆芯稳态计算
Pub Date : 2021-09-20 DOI: 10.25073/2588-1124/vnumap.4621
N. Dung, Tran Viet Phu, D. Hartanto, Luu Thi Phuong Lan, Mai Viet Thuan, P. Ha
This paper presents the steady-state analysis results of the OECD/NEA and U.S. NRC PWR MOX/UO2 (MOX: Mixed Oxide) Core Transient Benchmark with the modern MCNP6 Monte Carlo code based on the ENDF/B-VII.1 evaluated nuclear data library. The purpose was to verify an MCNP6 model proposed for calculations of a heterogeneous MOX/UO2 fuelled PWR core, which has different neutronic characteristics from the popular homogeneous ones loaded with the UO2 fuel due to its partial loading of the MOX fuel. The effective neutron multiplication factors, assembly power distributions, and control rod worths calculated using MCNP6 showed a reasonable agreement within 390 pcm, 6%, and 175 pcm, respectively, with the available benchmark data. The discrepancies between the MCNP6 results and the benchmark data were also discussed. Consequently, these results obtained with MCNP6 and ENDF/B-VII.1 can be considered as a new full-core heterogeneous transport solution to supplement for the available benchmark solutions at the steady-state conditions.
本文介绍了基于ENDF/B-VII的现代MCNP6蒙特卡罗代码对OECD/NEA和美国NRC压气堆MOX/UO2 (MOX:混合氧化物)堆芯瞬态基准的稳态分析结果。1评价核数据库。目的是验证MCNP6模型,该模型用于计算非均相MOX/UO2燃料的压水堆堆芯,该堆芯由于部分装载MOX燃料而与装载UO2燃料的均相堆芯具有不同的中子特性。使用MCNP6计算的有效中子倍增系数、装配功率分布和控制棒价值分别在390 pcm、6%和175 pcm范围内与现有基准数据吻合。还讨论了MCNP6结果与基准数据之间的差异。因此,这些结果是通过MCNP6和ENDF/B-VII获得的。1可以看作是一个新的全核异构传输解决方案,以补充稳态条件下可用的基准解决方案。
{"title":"Steady State Calculations of the PWR MOX/UO2 Core with the Monte Carlo Code MCNP6","authors":"N. Dung, Tran Viet Phu, D. Hartanto, Luu Thi Phuong Lan, Mai Viet Thuan, P. Ha","doi":"10.25073/2588-1124/vnumap.4621","DOIUrl":"https://doi.org/10.25073/2588-1124/vnumap.4621","url":null,"abstract":"This paper presents the steady-state analysis results of the OECD/NEA and U.S. NRC PWR MOX/UO2 (MOX: Mixed Oxide) Core Transient Benchmark with the modern MCNP6 Monte Carlo code based on the ENDF/B-VII.1 evaluated nuclear data library. The purpose was to verify an MCNP6 model proposed for calculations of a heterogeneous MOX/UO2 fuelled PWR core, which has different neutronic characteristics from the popular homogeneous ones loaded with the UO2 fuel due to its partial loading of the MOX fuel. The effective neutron multiplication factors, assembly power distributions, and control rod worths calculated using MCNP6 showed a reasonable agreement within 390 pcm, 6%, and 175 pcm, respectively, with the available benchmark data. The discrepancies between the MCNP6 results and the benchmark data were also discussed. Consequently, these results obtained with MCNP6 and ENDF/B-VII.1 can be considered as a new full-core heterogeneous transport solution to supplement for the available benchmark solutions at the steady-state conditions.","PeriodicalId":303178,"journal":{"name":"VNU Journal of Science: Mathematics - Physics","volume":"256 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124214302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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VNU Journal of Science: Mathematics - Physics
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