In this paper, according to the requirement of the focused sound field measurement, a focused sound field measurement system was established based on the LabVIEW virtual instrument platform. The system can automatically search the focus position of the sound field, and adjust the scanning path according to the size of the focal region. Three-dimensional sound field scanning time reduced from 888 hours in uniform step to 9.25 hours in variable step. The efficiency of the focused sound field measurement was improved. There is a certain deviation between measurement results and theoretical calculation results. Focal plane--6 dB width difference rate was 3.691%, the beam axis--6 dB length differences rate was 12.937%.
Computer Simulation ; Numerical Analysis, Computer-Assisted ; Software ; Sound

There have been insufficient numerical methods for particular description and quantitative evaluation of left ventricular diastolic function in the studies in this area. We therefore have summarized the computational models of the affecting factors for diastolic function from five aspects, i. e. the geometry shape of left ventricular, myocardial stiffness, myocardial viscosity, myocardial relaxation and ventricular interaction respectively. Controlling the sensitive parameters and having a mathematical description on left ventricular diastolic dysfunction can provide numerical methods for clinical diagnosis and quantitative evaluation of the disease.
Computer Simulation ; Diastole ; physiology ; Humans ; Models, Theoretical ; Numerical Analysis, Computer-Assisted ; Ventricular Function, Left ; physiology

This paper is aimed to fulfill a prototype system used to classify and retrieve retinal image automatically. With the content-based image retrieval (CBIR) technology, a method to represent the retinal characteristics mixing the fundus image color (gray) histogram with bright, dark region features and other local comprehensive information was proposed. The method uses kernel principal component analysis (KPCA) to further extract nonlinear features and dimensionality reduced. It also puts forward a measurement method using support vector machine (SVM) on KPCA weighted distance in similarity measure aspect. Testing 300 samples with this prototype system randomly, we obtained the total image number of wrong retrieved 32, and the retrieval rate 89.33%. It showed that the identification rate of the system for retinal image was high.
Algorithms ; Fundus Oculi ; Humans ; Image Processing, Computer-Assisted ; methods ; Information Storage and Retrieval ; methods ; Numerical Analysis, Computer-Assisted ; Ophthalmoscopy ; standards ; Pattern Recognition, Automated ; methods ; Retina ; pathology ; Retinal Vessels ; pathology

The tip structure is one of the key factors to determine the performance of left ventricular assist device (LVAD) inflow cannulas. The tip structure influences the thrombosis, hemolysis in cannula and left ventricle and suction leading to obstruction in ventricle. We designed four kinds of inflow cannulas that had different tips and built the numerical models of the four historical used inflow cannulas inserted into the apex of left ventricle. We computed the hemodynamic characteristics of inflow cannulas insertion by Fluent software. We researched the backflow, turbulent flow and pressure distribution of the four inflow cannulas. The results showed that the trumpet tipped inflow cannula had smooth flow velocity distribution without backflow or low velocity flow. The trumpet tipped inflow cannula had the best blood compatibility characteristics. The trumpet structure could prevent obstruction. The caged tipped cannula had serious turbulent flow which could possibly cause thrombosis and the low pressure near left ventricle wall and easily lead to ventricle collapse. The trumpet tipped inflow cannula has the best blood compatibility and is difficult to be obstructed. The trumpet tipped inflow cannula is fit to long-term use LVAD.
Catheters ; Computer Simulation ; Equipment Design ; Heart Failure ; therapy ; Heart-Assist Devices ; adverse effects ; Hemolysis ; Humans ; Numerical Analysis, Computer-Assisted ; Thrombosis ; prevention & control ; Ventricular Dysfunction, Left ; prevention & control

OBJECTIVETo evaluate the impact of breast density on computer-aided detection (CAD) for breast cancer and the CAD false-positive rate of normal controls.

METHODSTwo hundred and seventy-one histologically proven breast malignant lesions (from Feb. 2008 to Dec. 2009) and 238 randomly selected normal cases were classified by mammographic density according to the American College of Radiology breast imaging reporting and data system (BI-RADS). Mammograms of BI-RADS 1 or BI-RADS 2 density were categorized as non-dense breasts, and those of BI-RADS 3 or BI-RADS 4 density were categorized as dense breasts. Full-field digital mammography (GEMS Senographe) were performed in all patients and controls with craniocaudal (CC) and mediolateral oblique (MLO) views. Then the image data were transferred to review workstation (SenoAdvantage), and the lesions were marked by Second Look Digital CAD system (version 7.2, iCAD). The differences of sensitivity and false-positive rate between dense and non-dense breasts were compared.

RESULTSOverall, the sensitivity of CAD in detection of cancers was 84.1% (228/271), there was a statistically significant difference in CAD of cancers in dense versus non-dense breasts (P = 0.015). The sensitivity of CAD in detection of mass cancers was 76.5% (186/243), in detection of calcification cancers was 79.1% (125/158), there was no statistically significant difference in CAD performance for the detection of mass cancers versus calcification cancers (P = 0.547). There was a significant difference in the CAD performance for the detection of mass cancer cases in non-dense versus dense breasts (P = 0.001), but no significant difference in the CAD for the detection of calcification cancers in non-dense versus dense breasts (P = 0.216). In the controls, the distribution of mass false-positive marks did not differ significantly between non-dense and dense breast tissue cases (P = 0.207), but the distribution of calcification false-positive marks differed significantly between non-dense and dense breast tissue cases (P = 0.001). There was a statistically significant difference of false-positive marks in non-dense versus dense breasts (P = 0.043).

CONCLUSIONSThe sensitivity of CAD in the detection of breast cancers is impacted by breast density. There is a statistically significant difference in the CAD performance for the detection of cancer cases in non-dense versus dense breasts. The false-positive rate of CAD is lower in dense versus non-dense breasts. It appears difficult for CAD in the early detection of breast cancer in the absence of microcalcifications, particularly in dense breasts.

Adenocarcinoma, Mucinous ; diagnostic imaging ; pathology ; Adult ; Aged ; Aged, 80 and over ; Breast ; pathology ; Breast Neoplasms ; diagnostic imaging ; pathology ; Calcinosis ; diagnostic imaging ; Carcinoma, Ductal, Breast ; diagnostic imaging ; pathology ; Carcinoma, Lobular ; diagnostic imaging ; pathology ; Carcinoma, Papillary ; diagnostic imaging ; pathology ; False Positive Reactions ; Female ; Humans ; Mammography ; methods ; Middle Aged ; Numerical Analysis, Computer-Assisted ; Radiographic Image Interpretation, Computer-Assisted

The function theory of an anesthesia vaporizer was studied and the geometry configuration was measured in this study. The internal gas flow and mixing process in the anesthesia vaporizer were simulated using CFD method. Applying tracking in turbulent flow to stochastic particle, for the droplet of anesthesia drug, the moving track of droplet was traced. Based on the results, the internal gas flow variation, the concentration distribution of anesthesia drug volatilization process and mixing process with gas were ascertained. Numerical simulation results showed that, the diluted gas velocity reduction of internal flow in the anesthesia vaporizer was higher. Because of the anesthesia vaporizer geometry, the mixing process between anesthesia drug vapor and diluting gas was not homogeneous. This also influenced the stability and accuracy of anesthesia drug concentration. The optimization precept of anesthesia vaporizer is ascertained.
Anesthesia, Inhalation ; instrumentation ; Computer Simulation ; Humans ; Imaging, Three-Dimensional ; Nebulizers and Vaporizers ; standards ; Numerical Analysis, Computer-Assisted

Schistosomiasis is a kind of common disease around the riverside or lakeside areas, especially popular in rural areas, and causes huge economic loss. Based on existing schistosomiasis dynamic models and data, a new method of working out coefficients, and an improved model were provided in our study. The improved model can be applied to the study of the characteristics of transmission of schistosomiasis, and the effect of new control methods for schistosomiasis was evaluated.
Animals ; Cattle ; China ; Computer Simulation ; Humans ; Models, Theoretical ; Numerical Analysis, Computer-Assisted ; Schistosoma japonicum ; isolation & purification ; Schistosomiasis japonica ; epidemiology ; prevention & control ; transmission ; Snails ; parasitology

The distribution of shear stress on the bottom of the parallel plate flow chamber under different inlet velocities was analyzed by numerical simulation. In the present experimental study, the projection planes of the relative errors at 0.7% level were obtained, and then the efficient region and the actual entrance length were further corrected by introducing the concept of relative error. The results showed that the efficient region of the chamber increased with the direction of length while the inlet velocity was increased, and the actual entrance length was much greater than that of the theoretical entrance length. Therefore, in accordance to the needed range of shear stress in experiment and to the needed efficient region area, the optimum design of the flow chamber is necessary.
Algorithms ; Blood Flow Velocity ; Blood Pressure ; physiology ; Computer Simulation ; Humans ; Models, Cardiovascular ; Numerical Analysis, Computer-Assisted ; Pulsatile Flow ; Rheology ; Shear Strength ; Stress, Mechanical

The advent of parallel MRI over recent years has prompted a variety of techniques for performing parallel imaging. The main distinguishing feature among these is the specific way of solving the problem of image reconstruction from undersampled multiple-coil data. The clearest distinction in this respect is that between k-space method and image-domain method. The present paper reviews the basic reconstruction approaches, aiming to emphasize the common principles along with actual differences. To this end the treatment starts with an elaboration of the encoding mechanisms and sampling strategies that define the reconstruction task. Based on these considerations, the distinction between k-space and image-domain approaches is given. At the close of this paper are presented discussioins concerning noise propagation and control in parallel imaging and an outlook upon key issues to be addressed in the future.
Algorithms ; Humans ; Image Enhancement ; methods ; Image Interpretation, Computer-Assisted ; methods ; Magnetic Resonance Imaging ; methods ; Numerical Analysis, Computer-Assisted ; instrumentation ; Signal Processing, Computer-Assisted ; instrumentation

AIMTo investigate the relationship between the positioning of the lower central incisor and physical morphology of the surrounding alveolar bone.

METHODOLOGYThirty-eight patients (18 males, 20 females), with mean age of 13.4 years, were included in this study. As part of orthodontic treatment planning the patients were required to take dental Cone-beam CT (CBCT) covering the region of lower incisors, the surrounding alveolar bone and the mandibular symphysis. The cephalometric parameters were designed and measured to indicate the inclination of lower central incisor and physical morphology of the adjacent alveolar bone. Computer-aided descriptive statistical analysis was performed using SPSS 15.0 software package for Windows. A correlation analysis and a linear regression analysis between the incisor inclination and the alveolar bone morphology were performed.

RESULTSSignificant positive correlations were found between the lower central incisor inclination and the morphological contour of the alveolar bone (P < 0.05). The lower central incisor root apex was closer to the lingual alveolar crest when it was buccally inclined.

CONCLUSIONThe morphology of the alveolar bone may be affected by incisal inclination.

Adolescent ; Alveolar Process ; diagnostic imaging ; pathology ; Cephalometry ; methods ; Chin ; diagnostic imaging ; pathology ; Cone-Beam Computed Tomography ; methods ; Female ; Humans ; Incisor ; diagnostic imaging ; pathology ; Male ; Mandible ; diagnostic imaging ; pathology ; Numerical Analysis, Computer-Assisted ; Patient Care Planning ; Software ; Tooth Apex ; diagnostic imaging ; pathology