Observation of Fundamental and High Order Raman Modes of β-Carotenes in Pd OECC Thin Film by SERS

Raman spectra of purified oxygen evolution core complexes (Pd OECC) thin films on silver mirror substrates have been taken over the frequency range of 250-3100 cm -1 by surface enhanced Raman scattering (SERS). Besides the fundamental frequency modes of β_carotene in Pd OECC, many weak peaks are observed. According to the selection rules of overtone and combination bands, most of them are attributed to the second_order Raman spectra of β_carotene. Compared with the SERS of normal Pd OECC, the SERS of Pd OECC after strong illumination shows a decrease in scattering intensity and an increase in line widths, indicating changes of conformation and micro_environment of β_carotene. The results of SERS are consistent with the changes of absorption spectrum of Pd OECC induced by strong illumination. There are no changes that can be ascribed to new vibration bands, so it is deduced that Pd OECC on the silver mirror is identical to that in the solution. In summary, SERS proved a good method to study the photodamage mechanism of photosynthesis.

Single fundamental mode photonic crystal VCSEL with high power and low threshold current optimized by modal loss analysis

The characteristics of the photonic crystal vertical cavity surface emitting lasers（PhC-VCSELs） were investigated by using the full vector finite-difference time-domain（FDTD） method through the transverse mode loss analysis. PhC-VCSELs with different photonic crystal structures were analyzed theoretically and experimentally. Through combining the dual mode confinement of oxide aperture and seven-point-defect photonic crystal structure, the PhC-VCSELs with low threshold current of 0.9 mA and maximum output power of 3.1 mW operating in single fundamental mode were demonstrated. Mode loss analysis method was proven as a reliable and useful way to analyze and optimize the PhC-VCSELs.

Broad and ultra-flattened supercontinuum generation in the visible wavelengths based on the fundamental mode of photonic crystal fibre with central holes

By coupling a train of femtosecond pulses with 100 fs pulse width at a repetition rate of 76 MHz generated by a mode-locked Ti： sapphire laser into the fundamental mode of photonic crystal fibre （PCF） with central holes fabricated through extracting air from the central hole, the broad and ultra-flattened supercontinuum （SC） in the visible wavelengths is generated. When the fundamental mode experiences an anomalous dispersion regime, three phases in the SC generation process are primarily presented. The SC generation （SCG） in the wavelength range from 470 nm to 805 nm does not emerge significant ripples due to a higher pump peak power and the corresponding mode fields at different wavelengths are observed using Bragg gratings. The relative intensity fluctuations of output spectrum in the wavelength ranges of 530 nm to 640 nm and 543 nm to 590 nm are only 0.028 and 0.0071, respectively.

Influence of spherical aberrations on fundamental mode beam quality under different laser resonators

Spherical aberrations of the thermal lens of the active media are severe when solid state lasers are strongly pumped. The fundamental mode profile deteriorates due to the aberrations. Self-consistent modes of a resonator with aberrations are calculated by using the Fox-Li diffraction iterative algorithm. Calculation results show that the aberration induced fundamental mode beam quality deterioration depends greatly on the resonator design. The tolerance of a flat-flat resonator to the aberration coefficient is about 30λ in the middle of stability, where λ is the wavelength of laser beam. But for a dynamically stable resonator, 2λ of spherical aberration will create diffraction loss of more than 40%, if inappropriate design criteria are used. A birefringence compensated laser resonator with two Nd：YAG rods is experimentally studied. The experimental data are in quite good agreement with simulation results.

On the Fundamental Mode Love Wave in Devices Incorporating Thick Viscoelastic Layers

A detailed investigation is presented for Love waves （LWs） with thick viscoelastic guiding layers. A theoretical calculation and an experiment are carried out for LW devices incorporating an SU-8 guiding layer, an ST-90° X quartz substrate and two 28-μm periodic interdigital transducers. Both the calculated and the measured results show an increase in propagation velocity when h / λ〉0.05. The measured insertion loss of LWs is consistent with the calculated propagation loss. The insertion loss of bulk waves is also measured and is compared with that of LWs.

Conformal analysis of fundamental frequency of vibration of simple-supported elastic ellipse-plates with concentrated substance

Aimed at calculating the fundamental frequency of vibration of special-shaped, simple-supported elastic plates, Conformal Mapping theory is applied, and the mathematical method of trigonometric interpolation with interpolation points mutual iterative between odd and even sequences in boundary region is provided, as well as the conformal mapping function which can be described by real number region between complicated region and unit dish region is carried out. Furthermore, in the in-plane state of constant stress, vibrating function is completed by unit dish region method for simple-supported elastic plates with concentrated substance of complicated vibrating region, and the coefficient of fundamental frequency of the plate is analyzed. Meanwhile, taking simple-supported elastic ellipse-plates as an example, the effects on fundamental frequency caused by eccentric ratio, the coefficient of constant in-plane stress, as well as the concentrated substance mass and positions are analyzed respectively.

Characterization of Pathologic Cries of Newborns Based on Fundamental Frequency Estimation

The majority of the sick babies seem in good health at birth and early diagnosis of the various pathologies that can afflict newborn is crucial. For this reason we introduce in this paper the use of the fundamental frequency and the different modes of cries as Hyper-phonation, phonation and high pitched cries to differentiate the pathological cries from the cries of the healthy babies. The automatic estimation of these characteristics enabled us to establish a quantitative characterization of healthy newborn cries and pathologic newborn cries. The results obtained agree with the spectrographic analysis carried out on the healthy and pathologic cries of the newborns.

高校体育课程课内外一体化模式的研究

课内外一体化模式强调学生在体育学习过程中的主体地位,注重培养学生的体育兴趣、锻炼习惯,形成终身体育意识,使学生全面发展,提高身心健康水平。研究课内外一体化模式有助于优化教学内容、教学方法和评价体系,提高体育教学质量,使学生有更多的体育锻炼获得感。对课内外一体化模式进行研究有助于丰富我国体育教育理论体系,为学校体育教育改革提供理论支持。因此,该文针对高校体育课程课内外一体化模式进行探究。

新时代材料科学基础课程教学改革与实践探索

材料科学基础是一门理论性和应用实践性都很强的专业基础课程,其特点为概念抽象、内容多且理论性强,存在教师难教、学生难学等问题。结合新时代对创新复合型“材料人”的需求及课程特点,从教学方法、教材内容、教学实践及考核方式等方面对该课程进行教学改革与实践探索,以提高教学成效,提升学生的创新实践能力,促进新时代高质量“材料人”培养。

输入电压波动下变模态宽增益谐振变换器研究

针对传统LLC谐振变换器在宽输入下开关损耗过大、增益范围较窄、难以保持输出稳定的问题,研究一种变模态宽增益谐振变换器。该变换器及其控制策略能够依据输入电压的大小,在全桥和半桥两种模态之间自由切换,有效拓宽电压增益范围。通过对变换器谐振腔结构的优化,进一步拓宽增益,减小能量循环、降低开关管损耗,同时能够在电流传输中引入三次谐波,降低损耗。利用基波近似法对电压增益进行推导,绘制增益曲线图,分析谐振参数对电压增益的影响,根据需求设计合适的参数,并运用变频控制,通过调节输入电压,使得变换器运行在不同模态,实现电压平稳输出。搭建一台55~220 V输入、30 V输出的300 W实验样机,实验结果证明了所提变换器控制策略的有效性。

基于ANSYS的《机械设计基础》线上线下混合教学探索

随着信息技术的不断发展,线上线下混合教学模式已经逐渐成为现代教育的重要组成部分。在《机械设计基础》课程的教学改革实践中,通过结构化调查问卷的方式进行学情分析,在学情分析的基础上探讨了基于ANSYS软件的线上线下混合教学模式的优势和应用。结果表明,在《机械设计基础》课程线上线下教学中融入ANSYS软件,可以让学生更好地了解机械设计中零件的结构、工作原理、工作特点、应力分析等相关知识,问题分析更加透彻。同时可以提高学生的学习兴趣、实际操作能力和互动性,提高教学效果,对学生的毕业设计、工程实践具有重要意义。

六分量地震观测在工程勘查中的应用试验

利用面波频散曲线反演地下介质的S波速度结构,是浅层工程地震领域一种重要的方法技术.传统的面波法包括主被动源的面波多道分析方法(MASW)和被动源的空间自相关(SPAC)方法,均需要多台地震仪同时记录地面振动;而记录平动和旋转运动的单台站六分量地震数据理论上也可以获得面波频散曲线.本文以河北唐山城区煤矿采空区浅层工程勘探实际六分量地震数据为例,对比了利用单台站六分量地震数据与主、被动源法多台站提取的Rayleigh波频散曲线.试验结果表明利用纵波扫描可控震源时,30 Hz以下频段利用单台站六分量地震数据提取的基阶Rayleigh波频散曲线与主、被动源MASW方法提取的频散曲线结果一致,说明在浅层工程地震勘查中,利用单物理点的六分量地震观测反演浅层横波速度是可行的.

基于紧凑型Nd∶YAG/PPMgLN模组的561 nm基模激光器

本文提出了一种非线性晶体的切角方法,通过切去谐振腔中掺氧化镁周期极化铌酸锂(PPMgLN)晶体输出端面的一角,改变输出端面的激光模式分布,从而实现了稳定的561 nm黄光激光的基模输出。利用有限差分本征模法,仿真出各种切角方案输出端面的激光模式分布,讨论其输出基模的原理,并通过实验测出各方案输出功率随泵浦功率的变化曲线。结果表明,当抽运功率为4.8 W时,实现了最高121 mW的基模输出,光-光转换效率为2.6%,中心波长为560.95 nm,半峰全宽为0.92 nm,3 h内波动性小于1.91%。与已报道的实验结果对比,该实验结果具有更小的结构尺寸,为紧凑型基模激光器提供重要参考。

JiTT教学模式在中职计算机应用基础课程中的实践

我国职业教育的发展对高素质技能型人才的培养提出了新的要求,针对传统灌输式教学、学习问题不能及时解决而导致的人才培养质量下降的问题,本文在对JiTT(Just-in-Time Teaching,JiTT)教学模式进行分析的基础上,设计了JiTT教学流程,并以计算机应用基础课程为例,进行了教学设计,旨在为推动中等职业教育的教学改革、增强学生学习的主动性以及提高职业人才的培养质量提供参考。

“MOOC+SPOC+翻转课堂”教学模式探索与实践——以“创新创业基础”课程为例

“互联网+教育”推动了高校创新创业教育的深化改革。在创新创业课程教学中,以MOOC和SPOC平台为代表的在线学习受到广大师生的认可和推崇,并不断融合和改革。“MOOC+SPOC+翻转课堂”教学模式不仅很好地融合了线上课程的资源优势,也对传统课堂加以翻转,更好地体现了以学生为主体的学习理念。以“创新创业基础”课程为例,探索“MOOC+SPOC+翻转课堂”教学模式的构建以及实践,提出通过MOOC、SPOC课前导学,小组合作、项目实践等课堂翻转探学,课后SPOC促学达成学生的成绩、完课率、实践参与及课程思政教学成效。

新时代高职院校体育核心素养评价体系的困境与实现路径

信息化背景下,加强以体育核心素养为导向的评价体系改革,是新时代体育教学革新的主题,也是新时代高职院校体育高质量发展的必然诉求。研究发现,传统体育教学评价体系存在着评价范围固化、忽视体育核心素养的价值属性、评价思维模式陈旧等实然困境。研究认为,融入新思想新理念,创新大学体育文化场域,运用数字技术创新评价模式,有助于破除现实困境。未来要以问题为导向,坚持守正创新,才能形成思维与技术突破,真正实现评价结果的系统性和科学性,促进高等职业教育高质量发展。

基于移动互联网络环境的大学课程学习模式研究——以“流体力学基础与液压气动传动技术”为例

本研究以“流体力学基础与液压气动传动技术”课程为例,研究了基于移动互联网环境下的大学课程学习模式。研究结果表明,移动学习可以为学生提供更加自由、灵活的学习方式,同时也可以提高学生的学习兴趣和学习效果。通过移动学习平台,教师可以更加有效地组织和管理课程内容,提高教学质量。但是,移动学习也存在着一些问题,如网络不稳定、设备不兼容等,需要教师和学生共同协作解决。

线上线下混合式教学模式在中职计算机基础课程中的应用探究

线上线下混合式教学模式应用于中职计算机基础课程教学中,有利于拓宽学生的学习渠道,培养学生的动手操作能力,激发学生的学习兴趣,提高学生的学习质效。在教学实践中,教师要做好前期准备和教学评价工作,精心设计教学过程,积极拓展课程资源以开拓教学视界,确定先导地位并规划教学方案,利用混合教学模式的优势培养学生的自学能力,以课后解疑释惑突破重难点,开展个性化辅导以促进学生思考,此落实混合式教学模式,提高计算机基础课程教学效率。

基阶与高阶瑞利波联合反演研究

研究了六层层状介质模型瑞利波基阶和高模式波相速度对横波速度、深度的敏感性,结果表明：基阶波较高模式波对7m以内浅部地层的横波速度更敏感,敏感性频带在10-25Hz范围内,峰值频带集中在18Hz左右;高模式波较基阶波对深部地层的横波速度更敏感,敏感性频带宽,峰值分散.基阶波对浅层的敏感性和高模式波穿透深度更深的特点为近地表岩土层二维横波速度结构的联合反演提供了前提条件.利用阻尼最小二乘SVD（Singular Value Decomposition）算法联合基阶与高模式波对理论模型和实例数据进行横波速度反演,反演结果表明联合反演增强了反演的稳定性,提高了反演的精度.