儿童颈部支气管源性囊肿超声表现1例

患儿女,5个月,因“发现胸骨上窝肿物渐增大5个月”入院。体格检查:胸骨上窝皮肤颜色及温度正常,可触及约2.0 cm×2.0 cm×1.5 cm肿物,质软,无压痛,界限清。超声检查:颈前皮下软组织内探及23.3 mm×15.5 mm×21.5 mm类圆形囊性包块,边界清,有包膜,其内透声差,可见细腻点状回声浮动,后方见增强效应,前方见细条状低回声与皮肤相通(图1A);CDFI未见血流信号(图1B);超声诊断:颈部囊性肿物。

高职制糖生产技术与管理专业试行现代学徒制存在的问题及对策研究

现代学徒制是提高高职教育质量的有效手段,是现代职业教育发展的需要。通过阐述制糖行业背景,分析制糖生产技术与管理专业实施现代学徒制现状及存在的问题,探讨相应的对策,旨在更好地培养制糖行业急需的技术技能型人才。

现代学徒制在高职制糖生产技术与管理专业的实现路径研究

现代学徒制作为一种职业教育人才培养模式,是高职院校人才培养模式改革的需要,是提高高职教育质量的需要。通过对新疆制糖业发展形势进行分析,阐述实施制糖生产技术与管理专业现代学徒制背景,探讨制糖生产技术与管理专业现代学徒制的实现路径,旨在更好地培养适应地方区域经济需要的制糖生产技术与管理专业高素质的技术技能型人才。

Toll样受体-2、4及单核细胞趋化蛋白-1与胎膜早破和绒毛膜羊膜炎的相关性研究

目的探讨Toll样受体(toll-like receptor,TLR)-2、TLR-4及单核细胞趋化蛋白-1(monocyte chemotactic protein-1,MCP-1)在胎膜早破(premature rupture of membrane,PROM)、绒毛膜羊膜炎中的临床意义。方法选择2017年9月至2018年1月在延边大学附属医院产科分娩的足月PROM患者52例(足月PROM组),未足月PROM患者46例(未足月PROM组),足月胎膜完整者40例(对照组)。显微镜下在绒毛膜及羊膜组织上有≥5个中性粒细胞浸润诊断为绒毛膜羊膜炎。产后取胎盘及胎膜组织行免疫组织化学染色,根据半定量积分法进行染色结果判定。未足月PROM组新生儿娩出断脐后,采集脐血检测MCP-1含量。采用秩和检验和χ^2检验进行统计分析。结果未足月PROM组和足月PROM组的胎盘组织中TLR-2阳性率[分别为80.43%(37/46)和78.85%(41/52)]、TLR-4阳性率[分别为86.96%(40/46)和82.69%(43/52)]均高于对照组[TLR-2阳性率:57.50%(23/40),TLR-4阳性率:62.50%(25/40)],差异有统计学意义(P<0.05);但未足月组与足月组比较差异无统计学意义(P>0.05)。46例未足月PROM患者中,根据胎盘胎膜病理检查发现绒毛膜羊膜炎11例,非绒毛膜羊膜炎35例。虽然绒毛膜羊膜炎组胎盘组织中的TLR-2阳性率[100.00%(11/11)]和TLR-4阳性率[90.91%(10/11)]均高于非绒毛膜羊膜炎组[分别为74.29%(26/35)和85.71%(30/35)],但差异均无统计学意义(P>0.05)。绒毛膜羊膜炎组新生儿脐血中的MCP-1含量[109.12(74.72~222.12)ng/L]高于非绒毛膜羊膜炎组[60.52(48.52~135.12)ng/L],差异有统计学意义(P<0.05)。结论胎盘组织中TLR-2、4的表达增高可能与PROM的发生发展有关。新生儿脐血中MCP-1含量升高可提示绒毛膜羊膜炎的发生。

四参数Logistic模型与双参数、三参数Logistic模型在语言测验中的拟合比较及睡眠现象检验--以来华留学生预科结业考试为例

四参数Logistic模型通过引入第4个参数,分析测验中高能力被试答错低难度试题的睡眠现象。运用四参数Logistic模型与双参数、三参数Logistic模型对汉语作为第二语言测验的实测数据进行分析,比对3种模型的分析结果,并通过四参数Logistic模型分析测验中的睡眠现象,结果表明:在模型拟合方面,四参数Logistic模型表现良好;四参数Logistic模型对项目区分度的估计结果高于双参数、三参数Logistic模型;语言测验存在睡眠现象时,被试能力值可能会被严重低估,高风险考试需要考虑使用四参数Logistic模型进行矫正;在语言测验中,睡眠现象是一种随机的失误现象,与所测的语言技能无关。

基于互联网的老年护理服务社会化模式探讨

随着我国老年人口的增加,老年护理服务面临的问题日益显现,实现老年护理服务的社会化是解决这一问题的重要途径。对老年护理服务的现状以及老年护理服务社会化的内涵进行分析,对借助于互联网和物联网建立社会化的老年护理服务模式的可靠性进行探讨。提出构建社会化护理模式的基本内容,护理服务社会化模式的完善需要政府和老年护理机构以及家庭共同参与,以加快老年护理服务社会化的进程。

基于“互联网+医疗保障”的老年医疗保障问题的思考

随着互联网技术的发展,“互联网+医疗保障”逐渐成为我国医疗保障领域的新业态,不断改变着现有的医疗保障模式。在对“互联网+医疗保障”的发展现状进行分析的基础上,对中国人口老龄化背景下老年医疗保障存在的问题进行了分析,提出了借助于互联网技术提供的便利,为老年人提供便捷的医疗和护理服务,完善老年人的医疗保险体系,提高老年人医疗服务保障和就医费用补偿水平的相关思考,以期能提高老年人的医疗保障水平。

ANALYTICAL SOLUTION OF FILLING AND EXHAUSTING PROCESS IN PNEUMATIC SYSTEM

The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.

Comprehensive Parameter for Analyzing Condensation in Pneumatic System

The condensation in pneumatic system is a complex physical phenomenon dependant upon status variation and phase transitions,which are related to the parameters of the compressed air,atmospheric conditions and the dimensions of the pneumatic components.Up to now,general research method for this problem is to calculate the status variation and movement quantity by numerical simulation and experiment directly.The comprehensive parameters composed of several different effect factors are rarely used to study the condensation.The composed components and the working conditions of each cylinder are different,a large number of experiments and complex calculations are necessary to determine the condensation.Additionally,the transferability of the determined results is poor.In this paper,the charging and discharging systems of serials cylinder with different structure parameters are studied.The condensation of the systems is observed and the effects of the structure parameters on condensation are analyzed.The changing trends of relative humidity,natural frequency and average speed against the structural parameters of the components during discharge of the pneumatic systems are analyzed.Three comprehensive parameters used to analyze and determine condensation composed by structure parameters of components are proposed,namely,the ratio of the effective area of the discharge tube and the container volume,the square root of the effective area of the discharge tube divided by the product of the container volume and the length of the discharge tube,and the discharge dimensionless tube-volume.The experimental results show that these comprehensive parameters can be used to quantitatively determine whether internal,external or zero condensation occurs in a pneumatic system,and can be also used to quantitatively analyze the experimental data of condensation in pneumatic systems directly.At the same time,the effect factors are too much and the effect relationships are very complex,which causes that the conclusions can＇t be put forward by using single effect factor in experimental data processing individually.The three obtained comprehensive parameters can be used to resolve the above problem.The proposed parameters can also resolve the problem of poor transferability in determining the state of condensation in pneumatic systems,and provide a novel method for the further study of condensation theory.

农村留守老人健康服务体系探讨

文章在对农村留守老人健康服务需求和健康服务现状进行分析的基础上,就构建农村留守老人健康服务体系,提出了完善农村留守老人的医疗保障体系、健康服务网络及社会支持系统等建议。

Unsteady Flow Characteristic of Low-Specific-Speed Centrifugal Pump under Different Flow-Rate Conditions

To investigate the unsteady flow characteristics in centrifugal pump, the flow field in a low-specific-speed centrifugal pump with complex impeller is numerically simulated under different conditions. The RNG κ-ε turbulence model and sliding mesh are adopted during the process of computation. The results show that the interaction between impeller and volute results in the unstable flow of the fluid, which causes the uneven distribution of pressure fluctuations around the circumference of volute. Besides the main frequency and its multiple frequency of pressure fluctuations in the centrifugal pump, the frequency caused by the long blades of complex impeller also plays a dominant role in the low-frequency areas. Furthermore, there exists biggish fluctuation phenomenon near the tongue. The composition of static pressure fluctuations frequency on the volute wall and blade outlet is similar except that the fluctuation amplitude near the volute wall reduces. In general, the different flow rates mainly have influence on the amplitude of fluctuation frequency in the pump, while have little effect on the frequency composition.

Influence of Tip End-plate on Noise of Small Axial Fan

In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent.

Effect of Inlet Guide Vanes on the Performance of Small Axial Flow Fan

Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed,which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations are performed. The steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simulation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the optimal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerodynamic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simulation results and the experimental data. It is found that the static characteristics of small axial flow fan is improved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field.

Effect of Tip Flange on Tip Leakage Flow of Small Axial Flow Fans

Aerodynamic performance of an axial flow fan is closely related to its tip clearance leakage flow. In this paper, the hot-wire anemometer is used to measure the three dimensional mean velocity near the blade tips. Moreover, the filtered N-S equations with finite volume method and RNG k-ε turbulence model are adopted to carry out the steady simulation calculation of several fans that differ only in tip flange shape and number. The large eddy simulation and the FW-H noise models are adopted to carry out the unsteady numerical calculation and aerodynamic noise prediction. The results of simulation calculation agree roughly with that of tests, which proves the numerical calculation method is feasible.The effects of tip flange shapes and numbers on the blade tip vortex structure and the characteristics are analyzed. The results show that tip flange of the fan has a certain influence on the characteristics of the fan. The maximum efficiencies for the fans with tip flanges are shifted towards partial flow with respect to the design point of the datum fan. Furthermore, the noise characteristics for the fans with tip flanges have become more deteriorated than that for the datum fan. Tip flange contributes to forming tip vortex shedding and the effect of the half-cylinder tip flange on tip vortex shedding is obvious. There is a distinct relationship between the characteristics of the fan and tip vortex shedding.The research results provide the profitable reference for the internal flow mechanism of the performance optimization of small axial flow fans.

Numerical and Experimental Study on Aerodynamic Performance of Small Axial Flow Fan with Splitter Blades

To improve the aerodynamic performance of small axial flow fan, in this paper the design of a small axial flow fan with splitter blades is studied. The RNG k-ε turbulence model and SIMPLE algorithm were applied to the steady simulation calculation of the flow field, and its result was used as the initial field of the large eddy simulation to calculate the unsteady pressure field. The FW-H noise model was adopted to predict aerodynamic noise in the six monitoring points. Fast Fourier transform algorithm was applied to process the pressure signal. Experiment of noise testing was done to further investigate the aerodynamic noise of fans. And then the results obtained from the numerical simulation and experiment were described and analyzed. The results show that the static characteristics of small axial fan with splitter blades are similar with the prototype fan, and the static characteristics are improved within a certain range of flux. The power spectral density at the six monitoring points of small axial flow fan with splitter blades have decreased to some extent. The experimental results show sound pressure level of new fan has reduced in most frequency bands by comparing with prototype fan. The research results will provide a proof for parameter optimization and noise prediction of small axial flow fans with high performance.

Study on Airflow Characteristics in the Semi-Closed Irregular Narrow Flow channel

The air-jet loom is widely used in the textile industry. The interaction mechanism of airflow and yarn is not clear in such a narrow flow channel, the gas consumption is relatively large, the yarn motion is unstable and the weft insertion is often interrupted during the operation. In order to study the characteristics of the semi-closed flow field in profiled dents, the momentum conservation equation is modified and the model parameters and boundary conditions are set. Compared with the different r, the ratio of profiled dent's thickness and gap, the results show that the smaller the r is, the smaller the velocity fluctuations of the airflow is. When the angle of profiled dents ? is close to zero, the diffusion of the airflow will be less. The experiment is also conducted to verify the result of the simulation with a high-speed camera and pressure sensor in profiled dents. The airflow characteristics in the semi-closed irregular narrow flow channel in the paper would provide the theoretical basis for optimizing the weft insertion process of the air-jet loom.

Research on the Response Characteristics of Solenoid Valve of the Air-jet Loom by Simulation

Solenoid valve is one of the executive parts of weft insertion control system. According to the response characteristics of the solenoid valve, an improved design becomes a necessity. Firstly, the numerical model was established after analyzing the solenoid valve during its start-up and shut-down. Comparing the simulation data with the practical data, it is verified that the numerical simulation model has a high feasibility. Secondly, excitation voltage and spring pre-compression were adjusted respectively, and the response rules after adjusting were investigated. The research of the study shows: the response time tends to be inverse proportional to the excitation voltage during start-up, and it becomes a constant value with the increase of the excitation voltage; the response time is proportional to the spring pre-compression when the solenoid valve starts up, it is inverse proportional to spring pre-compression when the solenoid valve shuts down. And the total response time is a constant value with the increase of the spring pre-compression. Therefore, the value of the excitation voltage and the spring pre-compression should be selected when the curve is becoming flatten. The results of the research can provide the reference to the further development of the solenoid valve.

Influence of Blade Outlet Angle on Performance of Low-specific-speed Centrifugal Pump

In order to analyze the influence of blade outlet angle on inner flow field and performance of low-specific-speed centrifugal pump, the flow field in the pump with different blade outlet angles 32.5°and 39° was numerically calculated. The external performance experiment was also carried out on the pump. Based on SIMPLEC algorithm, time-average N-S equation and the rectified k-ε turbulent model were adopted during the process of computation. The distributions of velocity and pressure in pumps with different blade outlet angles were obtained by calculation. The numerical results show that backflow areas exist in the two impellers, while the inner flow has a little improvement in the impeller with larger blade outlet angle. Blade outlet angle has a certain influence on the static pressure near the long-blade leading edge and tongue, but it has little influence on the distribution of static pressure in the passages of impeller. The experiment results show that the low-specific-speed centrifugal pump with larger blade outlet angle has better hydraulic performance.

Simulation and Experiment Research of Aerodynamic Performance of Small Axial Fans with Struts

Interaction between rotor and struts has great effect on the performance of small axial fan systems.The small axial fan systems are selected as the studied objects in this paper,and four square struts are downstream of the rotor.The cross section of the struts is changed to the cylindrical shapes for the investigation:one is in the same hydraulic diameter as the square struts and another one is in the same cross section as the square struts.Influence of the shape of the struts on the static pressure characteristics,the internal flow and the sound emission of the small axial fans are studied.Standard K-ε turbulence model and SIMPLE algorithm are applied in the calculation of the steady fluid field,and the curves of the pressure rising against the flow rate are obtained,which demonstrates that the simulation results are in nice consistence with the experimental data.The steady calculation results are set as the initial field in the unsteady calculation.Large eddy simulation and PISO algorithm are used in the transient calculation,and the Ffowcs Williams-Hawkings model is introduced to predict the sound level at the eight monitoring points.The research results show that:the static pressure coefficients of the fan with cylindrical struts increase by about 25%compared to the fan with square struts,and the efficiencies increase by about 28.6%.The research provides a theoretical guide for shape optimization and noise reduction of small axial fan with struts.

Influence of Coanda surface curvature on performance of bladeless fan

The unique Coanda surface has a great influence on the performance of bladeless fan.However,there is few studies to explain the relationship between the performance and Coanda surface curvature at present.In order to gain a qualitative understanding of effect of the curvature on the performance of bladeless fan,numerical studies are performed in this paper.Firstly,three-dimensional numerical simulation is done by Fluent software.For the purpose to obtain detailed information of the flow field around the Coanda surface,two-dimensional numerical simulation is also conducted.Five types of Coanda surfaces with different curvature are designed,and the flow behaviour and the performance of them are analyzed and compared with those of the prototype.The analysis indicates that the curvature of Coanda surface is strongly related to blowing performance,It is found that there is an optimal curvature of Coanda surfaces among the studied models.Simulation result shows that there is a special low pressure region.With increasing curvature in Y direction,several low pressure regions gradually enlarged,then begin to merge slowly,and finally form a large area of low pressure.From the analyses of streamlines and velocity angle,it is found that the magnitude of the curvature affects the flow direction and reasonable curvature can induce fluid flow close to the wall.Thus,it leads to that the curvature of the streamlines is consistent with that of Coanda surface.Meanwhile,it also causes the fluid movement towards the most suitable direction.This study will provide useful information to performance improvements of bladeless fans.