Exploration of the Integration of Positive Emotions and Flow Experience in STEAM Education

STEAM(science,technology,engineering,arts,and mathematics)education aims to cultivate innovative talents with multidimensional literacy through interdisciplinary integration and innovative practice.However,lack of student motivation has emerged as a key factor hindering its effectiveness.This study explores the integrated application of positive emotions and flow experience in STEAM education from the perspective of positive psychology.It systematically explains how these factors enhance learning motivation and promote knowledge internalization,proposing feasible pathways for instructional design,resource provision,environment creation,and team building.The study provides theoretical insights and practical guidance for transforming STEAM education in the new era.

NUMERICAL SIMULATION OF SUPERSONIC AXISYMMETRIC FLOW OVER MISSILE AFTERBODY WITH JET EXHAUST USING POSITIVE SCHEMES

Supersonic axisymmetric jet flow over a missile afterbody containing exhaust jet is simulated using the second order accurate positive schemes method developed for solving the axisymmetric Euler equations based on the 2-D conservation laws.Comparisons between the numerical results and the experimental measurements show excellent agreements.The computed results are in good agreement with the numerical solutions obtained by using third order accurate RKDG finite element method.The results show larger gradient at discontinuous points compared with those obtained by second order accurate TVD schemes.It indicates that the presented method is efficient and reliable for solving the axisymmetric jet with external freestream flows,and shows that the method captures shocks well without numerical noise.

Creation method for bi-level positive airway pressure based on pressure and flow feedback

An airway pressure and flow data acquisition system is developed to investigate the approach to building the bi-level positive airway pressure BiPAP in a ventilator.A number of experiments under different breathing situations and states are conducted and the experimental data are recorded.According to the data from these experiments the variation characteristics of the pressure and flow are analyzed using Matlab. The data analysis results show that the pressure increases while the flow decreases in the expiratory phase contrarily the pressure decreases while the flow increases in the inspiratory phase during the apnea state both the pressure and the flow remain unchanged. According to the above variation characteristics of breath a feedback-based method for creating bi-level positive airway pressure is proposed. Experiments are implemented to verify the BiPAP model. Results demonstrate that the proposed method works effectively in following respiration and caters well to most polypnea and apnea events.

Numerical Simulation of Unsteady Discharge Flow with Fluctuation in Positive Discharge Blower

The operating performance of positive discharge blower is markedly influenced by the pulsation of the discharge flow, but difficult to be measured with experimental methods. The internal and discharge flow of positive discharge blower with involute type three-lobe are numerically investigated, both in air cooling and countercurrent cooling conditions by means of computational fluid dynamics （CFD）. The unsteady compressible flow equations are solved using RNG x-ε turbulent model. The finite difference method and the second order upwind difference scheme are applied into discrete equations. In the numerical simulation, the dynamic mesh techniques are used to approach the rotating displacement of cell cubage and the alterability of inlet, outlet flow area. The non-uniform mesh is applied to the rotor-stator coupled area. The reliability of the numerical method is verified by simulating the inner flow and comparing with the semi-empirical theory. The flow flux curves and the distributing of velocity vector showed obvious vortex motion in all the discharge process, both in air cooling and countercurrent cooling conditions. These vortexes with different positions, intension and numbers at different rotating angles have remarkable influences on the discharge flux. For air cooling, the vortex produced a second pulsation with big-amplitude in a cycle, and led to the early appearance of maximum of backflow. For countercurrent cooling, the frequency of pulsation increased due to the pre-inflow, but the backflow at the outlet is prevented, also the pulsation strength has greatly decreased.

Sucrose pyrolysis assembling carbon nanotubes on graphite felt using for vanadium redox flow battery positive electrode

In the present paper, multi-walled carbon nanotubes（MWCNTs） are successfully assembled on graphite felt（GF） using sucrose pyrolysis method for the first time. The in situ formed pyrolytic carbon is chosen as the binder because it is essentially carbon materials as well as CNTs and GF which has a natural tendency to achieve high bonding strength and low contact resistance. The MWCNTs/GF electrode is demonstrated to increase surface area, reduce polarization, lower charge transfer resistance and improve energy conversion efficiency comparing with GF. This excellent electrochemical performance is mainly ascribed to the high electro-catalytic activity of MWCNTs and increasing surface area.

Unsteady Flow Simulations in a Three-lobe Positive Displacement Blower

To improve the performance of the positive displacement blower, it is imperative to understand the detailed internal flow characteristics or enable a visualization of flow status. However, the existing two-dimensional unsteady, three-dimensional steady or quasi-unsteady numerical simulation and theoretical analysis cannot provide the detailed flow information, which is unfavorable to improve the performance of positive displacement blower. Therefore, the unsteady flow characteristics in a three-lobe positive displacement blower are numerically investigated by solving the three-dimensional, unsteady, compressible Navier-Stokes equations coupled with RNG k-e turbulent model. In the numerical simulation, the dynamic mesh technique and overset mesh updating method are adopted. Due to the air being compressed in the process of the rotors rotating, the variation of the temperature field in the positive displacement blower is considered. By comparing the experimental measurements and the numerical results on the variation of flow rate with the outlet pressure, the maximum relative error of the flow rate is less than 2.15% even at the maximum outlet pressure condition, which means that the calculation model and numerical computational method used are effective. The numerical results show that in the intake region, the fluctuations of the inlet flow are greatly affected by the direction of the velocity vectors. In the exhaust region, the temperature changes significantly, which leads to the increase of the airflow pulsation. Through analysis on the velocity, pressure and temperature fields obtained from the numerical simulations, three-dimensional unsteady flow characteristics in the positive displacement blower are revealed. The studied results will provide useful reference for improving the performance and empirical correction in the design of the positive displacement blower.

Two integrable generalizations of WKI and FL equations: Positive and negative flows, and conservation laws

With the aid of Lenard recursion equations, an integrable hierarchy of nonlinear evolution equations associated with a 2 × 2 matrix spectral problem is proposed, in which the first nontrivial member in the positive flows can be reduced to a new generalization of the Wadati–Konno–Ichikawa(WKI) equation. Further, a new generalization of the Fokas–Lenells(FL) equation is derived from the negative flows. Resorting to these two Lax pairs and Riccati-type equations, the infinite conservation laws of these two corresponding equations are obtained.

Sleep Quality for Patients Receiving Noninvasive Positive Pressure Ventilation and Nasal High-Flow Oxygen Therapy in an ICU: Two Case Studies

Aim: The purpose of this case study was to examine the sleep quality of patients receiving noninvasive positive pressure ventilation (NPPV) or nasal high-flow oxygen therapy (NHF) in an intensive care unit and to investigate what types of nursing support are offered to such patients. Methods: We examined one patient each for NPPV and NHF. Polysomnography (PSG), review of the patient charts, and semi-structured interviews were used to collect the data for analysis. Results: Patients treated with NPPV or NHF demonstrated a noticeable reduction in deep sleep, with most of their sleep being shallow. Their sleep patterns varied greatly from those of healthy individuals. These results suggest that, in addition to experiencing extremely fragmented sleep, sleep in these patients was more likely to be interrupted by nursing interventions, such as during auscultation of breath sounds. Furthermore, it was revealed that “anxiety or discomfort that accompanies the mask or air pressure” in patients treated with NPPV and “discomfort that accompanies the nasal cannula or NHF circuit” in patients treated with NHF may be primary causes of disrupted sleep. Our results suggest a need for nursing care aimed at improving sleep quality in patients treated with NPPV or NHF.

Numerical Investigation of the Aerodynamic Performance Affected by Spiral Inlet and Outlet in a Positive Displacement Blower

The flow in the positive displacement blower is very complex.The existing two-dimensional numerical simulation cannot provide the detailed flow information,especially flow characteristics along the axial direction,which is unfavorable to improve the performance of positive displacement blower.To investigate the effects of spiral inlet and outlet on the aerodynamic performance of positive displacement blower,three-dimensional unsteady flow characteristics in a three-lobe positive displacement blower with and without the spiral inlet and outlet are simulated by solving Navier-Stokes equations coupled with RNG k-ε turbulent model.In the numerical simulation,the dynamic mesh technique and overset mesh updating method are used.The computational results are compared with the experimental measurements on the variation of flow rate with the outlet pressure to verify the validity of the numerical method presented.The results show that the mass flow rate with the change of pressure is slightly affected by the application of spiral inlet and outlet,but the internal flow state is largely affected.In the exhaust region,the fluctuations of pressure,velocity and temperature as well as the average values of velocity are significantly reduced.This illustrates that the spiral outlet can effectively suppress the fluctuations of pressure,thus reducing reflux shock and energy dissipation.In the intake area,the average value of pressure,velocity and temperature are slightly declined,but the fluctuations of them are significantly reduced,indicating that the spiral inlet plays the role in making the flow more stable.The numerical results obtained reveal the three-dimensional flow characteristics of the positive displacement blower with spiral inlet and outlet,and provide useful reference to improve performance and empirical correction in the noise-reduction design of the positive displacement blowers.

Flow Control for a Two-Stage Proportional Valve with Hydraulic Position Feedback

The current research mainly focuses on the flow control for the two-stage proportional valve with hydraulic position feedback which is named as Valvistor valve.Essentially,the Valvistor valve is a proportional throttle valve and the flow fluctuates with the change of load pressure.The flow fluctuation severely restricts the application of the Valvistor valve.In this paper,a novel flow control method the Valvistor valve is provided to suppress the flow fluctuation and develop a high performance proportional flow valve.The mathematical model of this valve is established and linearized.Fuzzy proportional-integral-derivative(PID)controller is adopted in the closed-loop flow control system.The feedback is obtained by the flow inference with back-propagation neural network(BPNN)based on the spool displacement in the pilot stage and the pressure differential across the main orifice.The results show that inference with BPNN can obtain the flow data fast and accurately.With the flow control method,the flow can keep at the set point when the pressure differential across the main orifice changes.The flow control method is effective and the Valvistor valve changes from proportional throttle valve to proportional flow valve.For the developed proportional flow valve,the settling time of the flow is very short when the load pressure changes abruptly.The performances of hysteresis,linearity and bandwidth are in a high range.The linear mathematical model can be verified and the assumptions in the system modeling is reasonable.

基于Moldflow软件对薄壁件某塑料喷嘴的注塑方案优化研究

喷嘴注塑产品的质量和性能很大程度上由注塑方案和工艺参数所决定,不当的注塑方案和工艺参数会导致充填不足、熔接线过多、翘曲变形量大等问题。为了可以减少生产周期,节约生产成本,利用三维软件UG对喷嘴进行建模,基于模流分析软件Moldflow软件对喷嘴注塑产品进行分析和优化,通过比较点浇口和侧浇口两种方案的分析结果,最终确定该产品点浇口的方案更好。并通过设计正交实验,得到优化后的工艺参数。

Numerical Investigation on the Secondary Flow Control by Using Splitters at Different Positions with Respect to the Main Blade

In turbomachinery,strong secondary flow can produce significant losses of total pressure near the endwall and reduce the efficiency of the considered turbomachine.In this study,splitters located at different positions with respect to the main blade have been used to reduce such losses and improve the efficiency of the outlet guide vane(OGV).Three different relative positions have been considered assuming a NACA 65-010 profile for both the main blade and the splitter.The numerical results indicate that splitters can effectively reduce the total pressure loss by suppressing the secondary flow around the main blade,but the splitters themselves also produce flow losses,which are caused by flow separation effects.

基于Moldflow的摩托车前中心盖模具设计

利用Moldflow软件对摩托车前中心盖进行了仿真分析,结合零件结构特点及成型工艺要求,设计了两种浇注系统方案,依据填充时间、流动前沿温度、冻结层因子和熔接线等仿真参数分析,优选出最佳浇口位置及数量,并依此确定采用“3点针阀式热流道+3点侧浇口”的进胶方式,最终设计了一副顺序阀热流道注塑模具。为解决T1区域型腔侧向抽芯的难题,设计了“垂直油缸+连接块+T形块”的抽芯机构,使模具结构更加紧凑;采用“大斜顶+小斜顶”组合的方式解决了倒扣方向不统一、抽芯空间小及难脱模的问题;导向定位系统采用了“0°精定位块+动定模止口”的方式,确保模具在开模和合模过程中能够准确、可靠地复位;采用类似“随形水路”的组合式冷却系统,滑块与大斜顶均设计有直径12 mm的独立冷却水路,其余部分设计有直径18 mm的水路,使模温更均匀,成型周期缩短约11%;试模后,模具运行平稳,各机构运动安全可靠,塑件精度及表面质量符合要求,可为同类模具的设计提供参考。

一类多参数Semipositone问题的多个正解

本文在一般有界区域上研究了一类多参数Semipositone问题.结合上下解方法与下降流不变集临界点理论,证明了此类问题有四个解,其中至少有两个是正的.

一类Semipositone问题的多个正解

结合上下解方法与下降流不变集临界点理论,在一般有界区域上,研究了一类Semipositone问题3个正解的存在性.

Demands, Resources and the Three Dimensions of Flow at Work. A Study among Professional Nurses

Within the healthcare context is very important to foster the dynamics leading to positive experiences at work, in order to promote work motivation and well-being. This study investigated the influence of some personal and job resources and of some job demands on the three dimensions (absorption, work enjoyment, intrinsic work motivation) of flow at work, on the basis of Job Demands-Resources Model. Flow at work is an inner experience arising during an activity in which people are immersed, feel motivated and enjoy it. Studies suggest that resources are the main antecedents of the flow experience. Respondents to the questionnaire were 197 nurses. Multiple regressions were performed to detect the resources and the demands that influence the three dimensions of flow at work. As expected, resources positively influenced the dimensions of flow at work, particularly work enjoyment. Job demands positively influenced absorption and negatively influenced the other two dimensions of flow at work. Human resources managers should promote flow at work supporting the availability of resources and monitoring the job demands.

不同通气模式结合Autoflow技术对先天性心脏病患儿术后肺的顺应性的影响

目的探讨不同通气模式结合Autoflow技术对先天性心脏病患儿术后肺的顺应性的影响。方法选择收治先天性心脏病患儿264例,所有患儿均于2017年1月-2018年12月在该院接受心内直视术治疗,按照随机数字表法分为实验组(n=132)和常规组(n=132)。实验组术后接受同步间歇指令通气+自动流速(SIMV+Autoflow)机械通气模式,常规组术后接受双相气道正压(BIPAP)机械通气模式,于采用相应辅助通气模式不同时间点记录两组气道阻力、血气分析、肺的顺应性。结果实验组TO PaCO2(39.12±6.82)mmHg、PaO2(168.92±61.93)mmHg、pH(7.39±0.12),和常规组的(38.71±6.79)mmHg、(168.15±62.23)mmHg、(7.41±0.13)对比差异无统计学意义(t=0.490,P=0.310;t=0.100,P=0.460;t=1.290,P=0.100)。实验组T2气道顺应性(47.27±10.22)mL/mbar、T3气道顺应性(51.73±10.15)mL/mbar,显著优于常规组的(44.53±9.34)mL/mbar、(46.93±8.46)m L/mbar(t=2.250,P=0.010;t=4.110,P=0.000)。结论在先天性心脏病患儿术后应用SIMV+Autoflow机械通气模式效果更为显著,其能够明显降低气道平均压和气道峰压,提升患儿肺的顺应性,并且对血流动力学和血气指标影响小。

Numerical and experimental investigation of leakage behavior at null position of high-pressure electro-pneumatic servo valve

The high-pressure electro-pneumatic servo valve(HESV)is a core element of the high-pressure pneumatic servo system.The annular clearance and the rounded corner of the spool-sleeve can cause the leakage at null position,thereby affecting high-precision control and stability of the servo system.This paper investigates the effects of the clearance structure on leakage behavior at null position of the HESV.A numerical approach was employed to evaluate the effects,and then a mathematical model was established to obtain the variation law of leakage flow rate at null position.The results indicate that the leakage flow rate at null position varies linearly with supply pressure and rounded corner radius,and is nonlinear as a quadratic concave function with annular clearance.The leakage flow rate of the annular clearance and the rounded corner varies with the valve opening in an invariable−nonlinear−linear trend.A test rig system of leakage behavior at null position of the HESV was built to confirm the validity of the numerical model,which agrees well with the conducted experimental study.

Lateral Migration and Nonuniform Rotation of Biconcave Particle Suspended inPoiseuille Flow

A biconcave particle suspended in a Poiseuille flow is investigated by the multiple-relaxation-time lattice Boltzmann method with the Galilean-invariant momentum exchange method.The lateral migration and equilibrium of the particle are similar to the Segré-Silberberg effect in our numerical simulations.Surprisingly,two lateral equilibrium positions are observed corresponding to the releasing positions of the biconcave particle.The upper equilibrium positions significantly decrease with the increasing Reynolds number,whereas the lower ones are almost insensitive to the Reynolds number.Interestingly,the regular wave accompanied by nonuniform rotation is exhibited in the lateral movement of the biconcave particle.It can be attributed to the fact that the biconcave shape in various postures interacts with the parabolic velocity distribution of the Poiseuille flow.A set of contours illustrate the dynamic flow field when the biconcave particle has successive postures in a rotating period.

Expiratory flow-limitation in mechanically ventilated patients: A risk for ventilator-induced lung injury?

Expiratory flow limitation(EFL), that is the inability of expiratory flow to increase in spite of an increase of the driving pressure, is a common and unrecognized occurrence during mechanical ventilation in a variety of intensive care unit conditions. Recent evidence suggests that the presence of EFL is associated with an increase in mortality, at least in acute respiratory distress syndrome(ARDS) patients, and in pulmonary complications in patients undergoing surgery. EFL is a major cause of intrinsic positive end-expiratory pressure(PEEPi), which in ARDS patients is heterogeneously distributed, with a consequent increase of ventilation/perfusion mismatch and reduction of arterial oxygenation. Airway collapse is frequently concomitant to the presence of EFL.When airways close and reopen during tidal ventilation, abnormally high stresses are generated that can damage the bronchiolar epithelium and uncouple small airways from the alveolar septa, possibly generating the small airways abnormalities detected at autopsy in ARDS. Finally, the high stresses and airway distortion generated downstream the choke points may contribute to parenchymal injury, but this possibility is still unproven. PEEP application can abolish EFL, decrease PEEPi heterogeneity, and limit recruitment/derecruitment.Whether increasing PEEP up to EFL disappearance is a useful criterion for PEEP titration can only be determined by future studies.