Direct Observation of Carrier Transportation Process in InGaAs/GaAs Multiple Quantum Wells Used for Solar Cells and Photodetectors

The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p-n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p-n junction escape from quantum wells and form photoeurrent rather than relax to the ground state of the quantum wells. The photo absorption coei^cient of multiple quantum wells is also enhanced by a p-n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.

Observations and Estimations of Directional Spectrum of Sea Waves

The directional spectrum is one of the basic characteristics of sea waves. The observations of directional spectrum of sea waves were successfully conducted at platform Bohai 8 during 1991 and 1992 using a wave gage array for the first time in China. Based on the field data, the directional spectrum which depends on the wave growth is given in this paper. Before observations, the effects of the type of gage array, the distance between the gages and the platform itself on the measured results and the precision of some methods for estimating the directional spectrum were investigated and compared with the methods of numerical simulations and model tests of multi-direcitonal irregular waves. This ensures the quality of the observations and estimations of the directional spectrum.

In-situ observation of porosity formation during directional solidification of Al-Si casting alloys

In-situ observation of porosity formation during directional solidification of two Al-Si alloys (7%Si and 13%Si) was made by using of micro-focus X-ray imaging.In both alloys,small spherical pores initially form in the melt far away from the eutectic solid-liquid (S/L) interface and then grow and coagulate during solidification.Some pores can float and escape from the solidifying melt front at a relatively high velocity.At the end of solidification,the remaining pores maintain spherical morphology in the near eutectic alloy but become irregular in the hypoeutectic alloy.This is attributed to different solidification modes and aluminum dendrite interactions between the two alloys.The mechanism of the porosity formation is briefly discussed in this paper.

Direct observation of oxygen vacancy formation and migration over ceria surface by in situ environmental transmission electron microscopy

The extremely high structural tolerance of ceria to oxygen vacancies(Ov)has made it a desirable catalytic material for the hydrocarbon oxidation to chemicals and pharmaceuticals and the reduction of gaseous pollutants.It is proposed that the formation and diffusion of Ov originate from its outstanding reduction property.However,the formation and diffusion process of Ov over the surface of ceria at the atomic level is still unknown.Herein,the structural and valence evolution of CeO_(2)(111)surfaces in reductive,oxidative and vacuum environments from room temperature up to 700℃was studied with in situ aberration-corrected environmental transmission electron microscopy(ETEM)experiments.Ov is found to form under a high vacuum at elevated temperatures;however,the surface can recover to the initial state through the adsorption of oxygen atoms in an oxygen-contained environment.Furthermore,in hydrogen environment,the step-CeO_(2)(111)surface is not stable at elevated temperatures;thus,the steps tend to be eliminated with increasing temperature.Combined with first-principles density function calculations(DFT),it is proposed that O-terminated surfaces would develop in a hypoxic environment due to the dynamic diffusion of Ov from the outer surface to the subsurface.Furthermore,in a reductive environment,H2 facilitates the formation and diffusion of Ov while Ce-terminated surfaces develope.These results reveal dynamic atomic-scale interplay between the nanoceria surface and gas,thereby providing fundamental insights into the Ov-dependent reaction of nano-CeO_(2) during catalytic processes.

An Improved Stator Flux Observation Method of Permanent Magnet Synchronous Motor

The stator flux and electromagnetic torque observation is the basis of direct torque controlled permanent magnet synchronous motor( PMSM) drive system. However,the traditional stator flux observer based on voltage model is affected by integral initial values and integral drift,that based on current model is affected by the parameters of PMSM,so a new stator flux observation method is proposed based on an improved secondorder generalized integrator( SOGI). Compared to the stator flux observation method based on the conventional SOGI,the proposed method can not only overcome the influence of integral initial values and integral drift,but also completely eliminate the DC offset's influence. Therefore,the observation accuracy of stator flux is further improved. The simulation and experimental results both show that the proposed method has a higher stator flux and electromagnetic torque observation precision.

Robust Position Observer for Sensorless Direct Voltage Control of Stand-Alone Ship Shaft Brushless Doubly-Fed Induction Generators

The aim of this paper is to investigate an adaptive sensorless direct voltage control(DVC)strategy for the stand-alone ship shaft brushless doubly-fed induction generators(BDFIGs).The proposed new rotor position observer using the space vector flux relations of BDFIG may achieve the desired voltage control of the power winding(PW)in terms of magnitude and frequency,without any speed/position sensors.The proposed algorithm does not require any additional observers for obtaining the generator speed.The proposed technique can directly achieve the desired DVC based on the estimated rotor position,which may reduce the overall system cost.The stability analysis of the proposed observer is investigated and confirmed with the concept of quadratic Lyapunov function and using the multi-model representation.In addition,the sensitivity analysis of the presented method is confirmed under different issues of parameter uncertainties.Comprehensive results from both simulation and experiments are realized with a prototype wound-rotor BDFIG,which demonstrate the capability and efficacy of the proposed sensorless DVC strategy with good transient behavior under different operating conditions.Furthermore,the analysis confirms the robustness of the proposed observer via the machine parameter changes.

Research on Direct Yaw Moment Control Strategy of Distributed-Drive Electric Vehicle Based on Joint Observer

Combined with the characteristics of the distributed-drive electric vehicle and direct yaw moment control,a double-layer structure direct yaw moment controller is designed.The upper additional yaw moment controller is constructed based on model predictive control.Aiming at minimizing the utilization rate of tire adhesion and constrained by the working characteristics of motor system and brake system,a quadratic programming active set was designed to optimize the distribution of additional yaw moments.The road surface adhesion coefficient has a great impact on the reliability of direct yaw moment control,for which joint observer of vehicle state parameters and road surface parameters is designed by using unscented Kalman filter algorithm,which correlates vehicle state observer and road surface parameter observer to form closed-loop feedback correction.The results show that compared to the“feedforward+feedback”control,the vehicle’s error of yaw rate and sideslip angle by the model predictive control is smaller,which can improve the vehicle stability effectively.In addition,according to the results of the docking road simulation test,the joint observer of vehicle state and road surface parameters can improve the adaptability of the vehicle stability controller to the road conditions with variable adhesion coefficients.

The Impact of Directly Observed Therapy on Preventive Treatment for Latent Tuberculosis Infection among Students in Dalian, China

Preventive treatment has an essential effect on latent tuberculosis infection(LTBI)[purified protein derivative(PPD)induration≥15 mm].Between2010 and 2013,there were 6 tuberculosis(TB)outbreaks in the universities in Dalian,China.So far,in Dalian,the directly observed therapy(DOT)and

Rainfall and Runoff Observations in the Subtropical Forest of Okinawa Island, Japan

We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level data (recorded by a pressure-type water level gauge installed in a box culvert) and a discharge rating curve (derived from in situ observations). Water balance calculations for 2010 showed that the rainfall, runoff and evapotranspiration losses (= rainfall – runoff) were 3403.6 mm, 2285.7 mm and 1117.4 mm, respectively. This result was in agreement with previous results from other forested experimental catchments in this region. Direct runoff, as a proportion of event total rainfall, can be expressed by the empirical equation (Qdirect = 0.0048, Pevent 1.7971, R2 = 0.9599). When Pevent was 100 mm or less, the ratios of Qdirect to Pevent were less than 15% in general. When Pevent exceeded 100 mm, the ratios were 20% - 30%.

Association of Directly Observed Prophylaxis with Sulfadoxine-Pyrimethamine for Prevention of Mother-to-Fetus Transmission of Malaria, Kananga, Democratic Republic of the Congo

Over 90 percent of illness and death attributable to malaria occurs in Sub-Saharan Africa, frequently among pregnant women and young children. Infection with P. falciparum results in high parasitemia percentages and it is the most frequent cause of malaria that results in illness and death in Africa. In areas with holoendemic transmission, such as in most of the Democratic Republic of the Congo (DRC), adults are exposed to malaria every few days or weeks throughout life and, if surviving, have relatively mild bouts of illness because of acquired immunity.

An Observing Method for Flux and Speed with Direct Torque Control

An observing method for stator flux and rotor flux is presented. Based on the proposed flux observing method, a novel speed estimator has been designed. At last, the speed estimator combined with the flux observing is applied in the direct torque control system without speed sensor. The simulation results show that these methods can improve the accuracy of speed observing and the low speed performance of direct torque control system, and strengthen the robustness of system.

Mini-CEX联合DOPS评价体系在牙体牙髓病学临床教学中的应用研究

目的:研究联合应用迷你临床演练评估(mini-clinical evaluation exercise,Mini-CEX)与诊疗技能直接观察法(direct observation of procedural skills,DOPS)评估量表在口腔医学专业本科生牙体牙髓病学临床实习教学中的应用效果。方法:对60名在牙体牙髓科实习的口腔医学专业本科生分别在实习开始(0个月)、实习中期(1个月)和实习结束(3个月)时采用Mini-CEX评测量表评测综合病例诊治能力,DOPS量表测评窝洞制备、橡皮障隔离、开髓术等基本临床技能操作并行统计学分析。结果:共完成Mini-CEX量表评测180次,DOPS量表评测540次。随着实习阶段的进展,两种量表的得分均逐步提高,差异有统计学意义(P<0.05)。结论:联合应用Mini-CEX与DOPS评估方法能够有效促进实习医师临床实践能力的培养,值得在牙体牙髓病学的本科临床实习教学中推广。

改良Peyton四步教学法联合DOPS在西藏临床技能培训中的应用

目的探讨基于改良Peyton四步教学法的模拟教学联合操作技能直接观察(direct observation of procedural skills,DOPS)评估方法在西藏临床技能培训中的应用效果。方法选取西藏边坝县人民医院2021年5月—2022年5月参加临床技能培训的51名医护人员为研究对象,随机分为试验组与对照组。试验组采用结合改良Peyton四步教学法进行成人男性导尿术教学,并在培训开始前、培训中期及培训结束后,由带教教师采用DOPS评估方法对学员进行测评。对照组采用传统临床技能培训方法进行教学。在培训结束后发放满意度调查问卷,以了解学员对该教学模式的满意度。结果试验组技能考核平均成绩(90.12±5.50)分,对照组技能考核平均成绩(79.36±6.95)分,两组间成绩比较,其差异具有统计学意义(P<0.001);DOPS评估量表显示,试验组学员在培训结束后临床操作各项能力均较前有显著提高,其差异均具有统计学意义(P<0.05);课后满意度调查结果显示,在赞同“增强相关基础知识”等6个方面,试验组与对照组比较,其差异均具有统计学意义(P<0.001)。结论基于改良Peyton四步教学法的模拟教学联合DOPS评估方法的教学模式可提高西藏藏区医护人员的临床技能操作水平,适合在藏区医护人员临床技能培训中推广。

Mini-CEX联合DOPS在疼痛科住院医师规范化培训中的应用

目的:探讨迷你临床演练评估体系(Mini-CEX)和操作技能直接观察评估体系(DOPS)在疼痛科住院医师规范化培训中的应用效果。方法:将32名住院医师随机分为试验组和对照组,分别采用Mini-CEX联合DOPS教学法和传统教学法进行带教,比较两组住院医师的出科考试成绩。结果:试验组Mini-CEX和DOPS成绩较入科时均显著提升,出科考试成绩明显高于对照组(P<0.05)。结论:在疼痛科住院医师规范化培训中应用Mini-CEX联合DOPS可以显著提高带教效果。

以学生为中心理念的形成性评价在临床实践教学管理中的应用思考

迷你临床演练评估(Mini-clinical Evaluation Exercise,Mini-CEX)与操作技能直接观察评估(Direct Ob⁃servation of Procedural Skill,DOPS)等形成性评价工具在岗位胜任力培养上具有显著优势,在临床实践教学中被大力推广。但由于教学管理理念和方法陈旧、师资能力不足、学生主动性缺乏等原因,效果不理想。以学生为中心是当前广为认可的主流教学理念,强调以学生发展和成效为中心。本文探讨通过改革教学管理,将以学生为中心理念深度融合在形成性评价的临床教学管理中,包括改进师资建设方式、培养学生主动学习意识、优化信息化手段、使用学习档案集实施全程管理等。

内科专业住院医师规范化培训指导医师线上DOPS培训的效果研究

目的探讨线上工作坊模式对内科专业住院医师规范化培训(简称住培)指导医师临床操作技能直接观察评估(direct observation of procedural skills,DOPS)师资培训的应用效果。方法选取2022年11月参加广东省内科专业住培普通师资培训班的45名指导医师为研究对象,采用线上分组讨论与教学视频评价反馈相结合的线上工作坊模式进行DOPS师资培训,采用问卷自评的方式评价指导医师对DOPS的掌握程度,并通过问卷调查了解培训前后指导医师对线上DOPS的培训需求与满意度。结果培训前仅17.8%的指导医师使用过DOPS量表;指导医师在培训后对DOPS的掌握程度明显高于培训前[(3.71±0.69)分比(2.29±0.87)分,P<0.01];且95.6%及以上的指导医师表示能够理解“DOPS评分项目的均质化制定方法”和“形成性反馈技巧”;100.0%的指导医师表示在今后住培教学中愿意尝试使用DOPS。课程的整体满意度评分为(8.40±1.70)分。结论线上工作坊模式对内科专业住培指导医师DOPS师资培训的短期效果满意,可进一步在住培形成性评价师资培训中推广应用。

Mini-CEX结合DOPS教学在产科护理教学中的应用

目的探讨对于产科护理实习生的教学工作,采用迷你临床演练评估(mini-clinical exercise evaluation,Mini-CEX)、操作技能直接观察评估(direct observation of procedural skills,DOPS)教学的应用效果。方法选择2022年2—12月接收的112名产科护理实习生,按随机数字表法分为研究组和对照组,每组56名。对照组采取常规护理教学方式,研究组采取Mini-CEX结合DOPS教学,经过2个月实习,对2组实习生进行Mini-CEX考核和DOPS考核,并且应用自制的满意度问卷来调查实习生的意见,评价教学满意度情况。结果研究组的产科护理实习生Mini-CEX考核的各项分值高于对照组,差异有统计学意义(P<0.001);研究组产科护理实习生的DOPS考核总分[(90.12±3.26)分]高于对照组DOPS考核总分[(81.15±3.12)分],差异有统计学意义(P<0.001);研究组的产科实习生满意度(94.64%)高于对照组满意度(78.57%),差异有统计学意义(P<0.05)。结论产科护理教学中应用Mini-CEX结合DOPS教学的效果满意,可提高实习生的满意度。

面向海浪遥感卫星标定的漂流波浪浮标关键技术研究

在精细化海洋观测领域,遥感卫星海浪方向谱的获取存在精度低、累积误差大等问题,设计了一种基于Transformer神经网络的海浪方向谱估计方法,通过引入稀疏自注意力机制以及物理引导模块等,实现海浪方向谱的高精度表达;海上试验测试结果表明,新提出的海浪方向谱估计方法与传统海浪方向谱估计方法相比,文章提出的模型估计方向谱更符合理论谱形,伪峰较少,平滑性和一致性方面表现较好,并且对数据噪声的容忍度更高。同时,设计了一种基于人工智能芯片的漂流波浪浮标系统,通过AI软硬件系统对不同任务进行动态调度分配,实现浮标低功耗运行,有效提升了波浪测量性能及海上工作时间,是遥感卫星高精度获取大范围、长时序全球性海洋观测数据的一种有效补充。

主特征向量加权的声矢量圆阵波束域多重信号分类测向方法

为降低声矢量圆阵方位估计方法的计算复杂度,避免声压振速联合处理需选取观测方向的问题,提出了一种主特征向量加权的声矢量圆阵波束域多重信号分类(MUSIC)测向方法。在信号总功率与噪声功率之比最大的优化准则下,求解得到单矢量传感器最优的加权向量,即主特征向量。结合主特征向量设计相应的波束形成矩阵,并从理论上对声矢量圆阵阵元域和波束域MUSIC的目标方位估计方差进行比较。推导了单矢量传感器的大特征值和信号功率、大特征值对应的特征向量和其导向向量之间的关系。通过仿真实验验证了基于主特征向量波束形成矩阵的有效性,所提方法具有较低的计算复杂度和良好的方位估计性能。水池实验数据分析表明,所提方法能够准确估计目标方位。

考虑输出约束及外部干扰的柔性航天器振动控制

针对具有输出约束及外部干扰的柔性航天器系统,提出一种直接关节力矩输入的振动控制方法。利用哈密顿原理,系统动力学特性由偏微分方程(PDE)和常微分方程(ODE)耦合组成的分布参数模型来描述。设计了非线性干扰观测器补偿外界干扰,并基于正切型障碍李雅普诺夫函数解决了航天器姿态角度误差和振动误差的多输出约束问题。利用扩展的拉塞尔不变集原理和半群理论证明了系统的渐近稳定性。不仅实现了姿态角的位置控制,还抑制了柔性航天器的弹性振动。通过对比仿真验证了所提方法的有效性。