能谱CT单能量模式与传统单电压扫描模式的相同CT值:体模研究

目的寻找能谱CT(GSI)显示不同碘浓度体模CT值与传统的单电压扫描(TPXI)相同时的单能量值(MEI)。方法应用聚丙烯材料容器型体模装载5、10、15和20 mg I/ml的碘对比剂,分别在空气背景及软组织背景下应用相同放射剂量的GSI扫描及TPXI扫描,TPXI扫描时分别采用80、100、120和140 kVp各采集一遍数据,两种扫描方式使用相同的转速(0.8 s)及Pitch值(0.984)对比剂对应TPXI扫描相同CT值的MEI。结果在TPXI不同的能量80、100、120和140kV下,MEI对应相同碘浓度CT值在空气背景下为52±1.0、58±1.3、62±1.4和66±1.3 keV;在软组织背景下为53±0.8、59±1.0、64±1.0和68±1.0 keV。结论 MEI在不同碘浓度时不同背景下均与TPXI各自kVp有良好的对应关系。

三维DSA距离测量准确性的模体定量评价研究

目的:运用模体定量评估三维DSA距离测量的准确性,以指导临床工作。方法:应用模拟动脉瘤模体和动脉狭窄模体,改变不同的扫描野、重建矩阵、模体方向来研究三维空间距离测量的准确性。通过对模体中球体和圆柱体三维容积重建图像尺寸测量与模体实际尺寸进行对比评估。结果:在三维图像重建中不同的扫描野、重建矩阵、模体方向均能清晰显示圆柱体、球体影像及模拟狭窄的程度。随着扫描野的缩小,对球体直径和狭窄直径的测量精度提高,对于圆柱体长度测量无变化。重建矩阵加大,球体直径测量误差减少(1283最大为0.36mm,2563最大为0.12mm)。圆柱体狭窄百分率测量误差大约为3%。结论:当选用合适的图像成像参数和后处理方法时,利用重建后的三维图像测量动脉瘤的大小和动脉狭窄的程度是相当可靠的。

深度学习重建算法对胸部低剂量CT肺结节测量及显示影响的模体研究

目的:基于胸部模体探讨不同强度深度学习重建算法(DLIR)对低剂量CT图像上肺结节显示及测量的影响。方法:采用包括纵隔、支气管血管束、软组织及骨骼的成年男性胸部仿真模型,内置直径(体积)为5 mm(66 mm^(3))、8 mm(268 mm^(3))和10 mm(523 mm^(3))的实性结节(SN)及磨玻璃结节(GGN),对其进行低剂量CT扫描(100 kVp、40 mA,CTDI VOI=0.84 mGy),采用标准卷积核的自适应统计迭代重建算法(ASIR-V)及中档(DLIR-M)和高档(DLIR-H)深度学习重建算法分别进行图像重建。在肺组织内放置ROI(面积100 mm^(2))测量肺组织CT值的标准差(SD)作为肺组织噪声(N肺组织)。选用肺结节CT影像辅助检测系统自动计算得到10 mm SN及10 mm GGN CT值的SD(即N结节)。计算3组图像上肺组织以及直径10 mm的SN和GGN的信噪比(SNR)及对比噪声比(CNR),以及所有结节的CT值和体积及其偏差度。对各组图像上肺组织及所有结节的噪声、支气管血管束的锐利度、SN和GGN的显示情况进行主观评价。结果:①在3组图像上,DLIR-H的肺组织、SN和GGN的噪声均为最低,肺组织的SNR、SN和GGN的SNR和CNR均为最高(P均<0.05),肺组织、SN和GGN显示情况的主观评分为最高(P均<0.001)。②三组图像上,三种直径SN的平均CT值偏差度的总体差异均无统计学意义(P均>0.05),三种直径GGN的平均CT值偏差度的总体差异均有统计学意义(P均<0.001);对于直径10 mm及5 mm的GGN,DLIR-M和DLIR-H图像上测得的平均CT值偏差度均小于ASIR-V(P均<0.001),DLIR-M和DLIR-H图像上测得的平均CT值偏差度的差异无统计学意义(P>0.05);对于直径8 mm的GGN,ASIR-V图像测得的平均CT值偏差度均小于DLIR-M、DLIR-H图像(P均<0.001),而DLIR-M与DLIR-H图像上测得的此指标值的差异无统计学意义(P=0.535)。③三组重建图像上测得10 mm、8 mm直径的SN及GGN体积偏差度的总体差异均无统计学意义(P均>0.05);对于直径5 mm的SN,ASIR-V与DLIR-M组间、DLIR-M与DLIR-H组间均无统计学差异(P均>0.05),ASIR-V图像测得偏差度小于DLIR-H(P=0.020);对于直径5 mm GGN,在DLIR-M、DLIR-H图像上测得的体积偏差度均较ASIR-V图像更小(P均<0.05),而DLIR-M、DLIR-H图像间偏差度的总体差异无统计学意义(P=0.476)。④主观评价结果:三组重建图像上肺组织噪声评分的总体差异具有统计学意义(H=15.58,P<0.001),在DLIR-H图像上该指标评分高于ASIR-V和DLIR-M图像(P<0.05),而ASIR-V与DLIR-M图像之间该指标评分的总体差异无统计学意义(P=0.849);三组重建图像的支气管血管束锐利度以及SN和GGN可见度主观评分的总体差异均无统计学意义(P均>0.05)。结论:低剂量下DLIR图像对结节CT值和体积的测量及显示情况与ASIR-V算法相当,而且在DLIR-M和DLIR-H图像上测得的5 mm GGN的平均CT值及体积更准确。对于肺结节的低剂量CT筛查及随访,采用深度学习重建算法是值得推荐的。

散射对PET/CT图像空间分辨率影响的模体研究

目的:对比研究有散射和无散射两种情形下PET/CT图像空间分辨率,为PET/CT在临床的应用提供参考。方法:使用DiscoveryElite型PET/CT设备,对椭圆柱分辨率模体模拟临床有水散射和空气中无散射状态下分别行PET/CT扫描。采用VPFX-S算法,对重建滤波核2.0~10.0 mm(间隔2.0 mm)、不同重建矩阵(128×128、192×192和256×256)进行重建。以线源半高宽(FWHM)表示重建图像的空间分辨率,计算5条线源5个层面上径向、轴向FWHM,并求平均值,运用配对t检验进行统计分析。结果:①128×128矩阵时,有散射时图像空间分辨率较无散射时低4.5%~17.1%;192×192矩阵时低2.4%~8.4%;256×256矩阵时低20.8%~29.6%;②无散射状态下,当滤波核为2.0~10.0 mm(间隔2.0 mm),中心位置空间分辨率分别为(3.68±0.05)mm、(4.12±0.04)mm、(6.11±0.04)mm、(8.12±0.04)mm和(9.11±0.04)mm。结论:临床中PET/CT图像空间分辨率较空气中低,且有散射情形的图像空间分辨率随位置及重建滤波核的变化规律与无散射情形下有差异。空气中测量的PET/CT NEMA空间分辨率不能反映临床情形下的空间分辨率。

运用模体定量评价三维DSA距离测量的准确性

目的运用模体定量评估三维DSA距离测量的准确性,以指导临床工作。方法应用模拟动脉瘤模体和动脉狭窄模体,改变不同的扫描野、重建矩阵、模体方向来研究三维空间距离测量的准确性。通过对模体中球体和圆柱体三维容积重建图像尺寸测量与模体实际尺寸进行对比评估。结果在三维图像重建中不同的扫描野、重建矩阵、模体方向均能清晰显示圆柱体、球体影像及模拟狭窄的程度。随着扫描野的缩小,对球体直径和狭窄直径的测量精度提高,对于圆柱体长度测量无变化。重建矩阵加大,球体直径测量误差减少(1283最大为0.36mm,2563最大为0.12mm)。圆柱体狭窄百分率测量误差大约为3%。结论当选用合适的图像成像参数和后处理方法时,利用重建后的三维图像测量动脉瘤的大小和动脉狭窄的程度是相当可靠的。

基于多层螺旋CT图像的机器深度学习技术测量仿真胸部体模肺结节体积及长径的效果

目的观察在多层螺旋CT图像中机器深度学习技术测量仿真胸部体模肺结节体积及长径的效果。方法取4种直径(5 mm、8 mm、10 mm、12 mm)的模拟肺结节共12个,每种直径结节都有3种CT密度值(100 HU、-630 HU、-800 HU)。将12枚模拟肺结节随机放置在仿真胸部体模,使用256排螺旋CT进行扫描,重建层厚分别为0.625 mm、1.25 mm、2.5 mm。使用机器深度学习软件检测所有的模拟肺结节,记录结节数目、长径、体积,计算结节长径、体积测量的绝对错误率(APE)。结果在不同图像层厚下,肺结节的长径和体积APE差异均无统计学意义(均P>0.05);不同直径肺结节的体积APE差异亦无统计学意义(P>0.05)。结论对于直径≥4 mm的肺结节,体积或是机器深度学习软件测量肺结节时更可靠的指标。重建层厚对机器深度学习技术测量肺结节长径及容积的结果影响较小,故采用人机协同阅片工作模式时,可适当加大图像层厚以减少影像医师阅片数量,缓解临床工作压力。

A Simulative Study on Effects of Climate Warming on Nutrient Contents and In Vitro Digestibility of Herbage Grown in Qinghai-Xizang Plateau

The increasing trend of air temperature along with the climate warming has been accepted gradually by scientists and by the general public. Qinghai_Xizang Plateau, a unique geographic unit due to high_altitude climate, is one of the most susceptible regions to climate warming. Its ecosystem is very fragile and sensitive to climate change. In order to get a better understanding of the impacts of climate warming on the nutrient contents of herbage grown in Qinghai_Xizang Plateau, a simulative study was implemented at Daban Moutain by using temperature differences resulted from sites selected at different altitudes and nutrient contents and in vitro digestibility were determined for assessing the quality of the grown herbage. There were significant downtrends in crude protein (CP), ether extract (EE) and nitrogen free extract (NFE) contents of herbage along with the increase of temperature. It had a positive correlation between temperature and content of acid detergent fibre (ADF), acid detergent lignin (ADL) in herbage. In vitro digestibility of herbage decreased along with the increase of temperature. The results of this study indicated that climate warming significantly influence nutrient contents and in vitro digestibility of herbage grown in Qinghai_Xizang Plateau. It is suggested that the future climate warming especially the gradual rise of the night temperature could cause negative effect on herbage quality grown in Qinghai_Xizang Plateau by decreasing CP, EE, and NFE contents and increasing some indigestible ingredients such as crude fibre (CF), neutral detergent fibre (NDF), ADF, and ADL. This, consequently, decreases the ruminant assimilation ability.

Numerical Study of Solid-Liquid Two-Phase Flow in StirredTanks with Rushton Impeller(Ⅱ) Prediction of Critical Impeller Speed

Three-dimensional solid-liquid flow is mathematically formulated by means of the 'two-fluid' approach and the two-phase k-ε-AP turbulence model. The turbulent fluctuation correlations appearing in the Reynolds time averaged governing equations are fully incorporated. The solid-liquid flow field and solid concentration distribution in baffled stirred tanks with a standard Rushton impeller are numerically simulated using an improved 'inner-outer'iterative procedure. The flow pattern is identified via the velocity vector plots and a recirculation loop with higher solid concentration is observed in the central vicinity beneath the impeller. Comparison of the simulation with experimental data on the mean velocities and the turbulence quantities of the solid phase is made and quite reasonable agreement is obtained except for the impeller swept volume. The counterpart of liquid phase is presented as well.The predicted solid concentration distribution for three experimental cases with the average solid concentration up to 20% is also found to agree reasonably with the experimental results published in the literature.

Training gastroenterology fellows to perform gastric polypectomy using a novel ex vivo model

AIM:To evaluate the effect of hands-on training of gastroenterology fellows in gastric polypectomy using an ex vivo simulator.METHODS:Eight gastroenterology fellows at Mackay Memorial Hospital,Taipei were evaluated in gastricpolypectomy techniques using a pig stomach with artificial polyps created by a rubber band ligation device.The performance of four second year(year-2)fellows who had undergone one year of clinical training was compared with that of four f irst year(year-1)fellows both before and after a 4-h workshop using the ex vivo simulator.The workshop allowed for hands-on train-ing in the removal of multiple artif icial polyps and the placement of hemoclips at the excision site.Evaluation included observation of technical skills,procedure time,and the fellows' conf idence scale.RESULTS:One week after the workshop,the year-1 fellows were re-evaluated and had significantly im-proved mean performance scores(from 17.9 ± 1.8 to 22.5 ± 0.7),conf idence scale(from 4.5 ± 1.0 to 7.8 ± 0.5)and procedure time(from 615.0 ± 57.4 s to 357.5 ± 85.0 s)compared with their baseline performance.After 4 h of training using the ex vivo simulator,the skills of the year-1 fellows were statistically similar to those of the year-2 fellows.CONCLUSION:Use of this ex vivo simulator significantly improved the endoscopic gastric polypectomy skills of gastroenterology fellows who had not had previous clinical training in gastric polypectomy.

Review Study on Main Models of Market Integration

With the endless strengthening of the economic globalization trend, the world market gradually steps into a new turn of the market integration period. Market integration in China is always the key study field of academic communities, but it is developed late, whatever content system or methodology shall be greatly improved as expected. This paper aims at summarizing and reviewing the study on the content system and main demonstrations of market integration in order to provide theoretical guide and methodological basis for related studies.

Construction and optimization of traditional Chinese medicine constitution prediction models based on deep learning

Objective To cater to the demands for personalized health services from a deep learning per-spective by investigating the characteristics of traditional Chinese medicine(TCM)constitu-tion data and constructing models to explore new prediction methods.Methods Data from students at Chengdu University of Traditional Chinese Medicine were collected and organized according to the 24 solar terms from January 21,2020,to April 6,2022.The data were used to identify nine TCM constitutions,including balanced constitution,Qi deficiency constitution,Yang deficiency constitution,Yin deficiency constitution,phlegm dampness constitution,damp heat constitution,stagnant blood constitution,Qi stagnation constitution,and specific-inherited predisposition constitution.Deep learning algorithms were employed to construct multi-layer perceptron(MLP),long short-term memory(LSTM),and deep belief network(DBN)models for the prediction of TCM constitutions based on the nine constitution types.To optimize these TCM constitution prediction models,this study in-troduced the attention mechanism(AM),grey wolf optimizer(GWO),and particle swarm op-timization(PSO).The models’performance was evaluated before and after optimization us-ing the F1-score,accuracy,precision,and recall.Results The research analyzed a total of 31655 pieces of data.(i)Before optimization,the MLP model achieved more than 90%prediction accuracy for all constitution types except the balanced and Qi deficiency constitutions.The LSTM model's prediction accuracies exceeded 60%,indicating that their potential in TCM constitutional prediction may not have been fully realized due to the absence of pronounced temporal features in the data.Regarding the DBN model,the binary classification analysis showed that,apart from slightly underperforming in predicting the Qi deficiency constitution and damp heat constitution,with accuracies of 65%and 60%,respectively.The DBN model demonstrated considerable discriminative power for other constitution types,achieving prediction accuracy rates and area under the receiver op-erating characteristic(ROC)curve(AUC)values exceeding 70%and 0.78,respectively.This indicates that while the model possesses a certain level of constitutional differentiation abili-ty,it encounters limitations in processing specific constitutional features,leaving room for further improvement in its performance.For multi-class classification problem,the DBN model’s prediction accuracy rate fell short of 50%.(ii)After optimization,the LSTM model,enhanced with the AM,typically achieved a prediction accuracy rate above 75%,with lower performance for the Qi deficiency constitution,stagnant blood constitution,and Qi stagna-tion constitution.The GWO-optimized DBN model for multi-class classification showed an increased prediction accuracy rate of 56%,while the PSO-optimized model had a decreased accuracy rate to 37%.The GWO-PSO-DBN model,optimized with both algorithms,demon-strated an improved prediction accuracy rate of 54%.Conclusion This study constructed MLP,LSTM,and DBN models for predicting TCM consti-tution and improved them based on different optimisation algorithms.The results showed that the MLP model performs well,the LSTM and DBN models were effective in prediction but with certain limitations.This study also provided a new technology reference for the es-tablishment and optimisation strategies of TCM constitution prediction models,and a novel idea for the treatment of non-disease.

Theory and experimental verification of valveless piezoelectric pump with rotatable unsymmetrical slopes

A valveless piezoelectric pump with rotatable unsymmetrical slopes is developed in this research.It has the following features:The pump integrates driving and transporting,and it can mix different fluids while transporting them.In this paper,firstly,the design of the valveless piezoelectric pump with rotatable unsymmetrical slopes was proposed,and the single-direction flow principle was explained.Then,the fluid mechanics model of the valveless piezoelectric pump with rotatable unsymmetrical slopes was established.Meanwhile,the numerical simulation of the pump was performed.Finally,the experiments on relationship between the rotation angles of the slope and the flow rates were conducted.The experimental results showed that the maximum flow was 32.32 mL min 1.The maximum relative error between the theoretical results and the experimental ones was 14.59%.For the relationship between rotation angles and flow ratio of two inlets,the relative error between the experimental and theoretical maxima was 3.75%.Thus,the experiments proved the feasibility of the pump design and verified the theory.

Mathematical study for peristaltic flow of Williamson fluid in a curved channel

In this paper, we have investigated the peristaltic flow of Williamson fluid in a curved channel. The governing equations of Williamson fluid model for curved channel are derived including the effects of curvature. The highly nonlinear partial differential equa- tions are simplified by using the wave frame transformation, long wavelength and low Reynolds number assumptions. The reduced nonlinear partial differential equation is solved analytically with the help of homotopy perturbation method. The physical features of pertinent parameters have been discussed by plotting the graphs of pressure rise, velocity profile and stream functions.

Analysis of Caenorhabditis elegans in microfluidic devices

Caenorhabditis elegans (C. elegans) is widely adopted as a model organism for a variety of biological studies including development, genetics and neurobiology. Micro-scale microfluidic technology is capable of handling single or populations of C. elegans in high throughput format and allows for the precise spatial and temporal control of their environment, which is well suited for the study of worms in different aspects. In this review, we highlight the recent advances in microfluidic technology for the analysis of worms ranging from behavioral studies to neurobiology. We believe that microfluidic device can further be applied to study the different aspects of worms, extending from fundamental investigation of behavioral dynamics to more complicated biological processes including neurochemistry and learning behaviors.

Combined Experimental and Numerical Investigations on the Roughness Effects on the Aerodynamic Performances of LPT Blades

The aerodynamic performance of a high-load low-pressure turbine blade cascade has been analyzed for three different distributed surface roughness levels(Ra) for steady and unsteady inflows. Results from CFD simulations and experiments are presented for two different Reynolds numbers(300000 and 70000 representative of take-off and cruise conditions, respectively) in order to evaluate the roughness effects for two typical operating conditions. Computational fluid dynamics has been used to support and interpret experimental results, analyzing in detail the flow field on the blade surface and evaluating the non-dimensional local roughness parameters, further contributing to understand how and where roughness have some influence on the aerodynamic performance of the blade. The total pressure distributions in the wake region have been measured by means of a five-hole miniaturized pressure probe for the different flow conditions, allowing the evaluation of profile losses and of their dependence on the surface finish, as well as a direct comparison with the simulations. Results reported in the paper clearly highlight that only at the highest Reynolds number tested(Re=300000) surface roughness have some influence on the blade performance, both for steady and unsteady incoming flows. In this flow condition profile losses grow as the surface roughness increases, while no appreciable variations have been found at the lowest Reynolds number. The boundary layer evolution and the wake structure have shown that this trend is due to a thickening of the suction side boundary layer associated to an anticipation of transition process. On the other side, no effects have been observed on the pressure side boundary layer.

Large shear rate behavior for the Hebraud-Lequeux model Dedicated to the NSFC-CNRS Chinese-French summer institute on fluid mechanics in 2010

The H@braud-Lequeux model is a model describing the flow of soft glassy material in a simple shear flow configuration. It is given by a kinetic/Fokker-Planck-type equation whose coefficients depend on the shear rate of the experiment. In this paper we want to study what happens to the stationary solutions of this model when the shear rate is asymptotically large. In order to do that, we expand the solution of the equation using singular perturbation tools. In the end, we rigorously prove the estimate of Hebraud and Lequeux that the material asymptotically behaves as a Newtonian fluid.

Biomathematical study of Sutterby fluid model for blood flow in stenosed arteries

In this paper, we have discussed the biomathematical analysis of Sutterby fluid model for blood flow in stenosed tapered arteries. The equations for the Sutterby fluid model are modeled in cylindrical geometry. The equations have been developed for the ease of mild stenosis. Perturbation solutions are attained in terms of small Sutterby fluid parameter β for the velocity, impedance resistance and wall shear stress. Three types of arteries i.e. converging, diverging and non-tapered have been considered for the analysis and discussion. Graphical results have been presented for different parameters of interest. Streamlines have been plotted at the end of the paper.

Scientific Evaluation and Regeneration of Eco-building Experience in Traditional Dwellings

In 1996, Department of Engineering and MaterialSciences,National Natural Science Foundation (NSFC), accepted the suggestion made by some experienced members of CAS and published the key support project Green Architecture System and Dwelling Pattern in application guide for NSFC project. The project research group, led by Prof.