Underwater plenoptic cameras optimized for water refraction.

By inserting a microlens array (MLA) between the main lens and imaging sensor, plenoptic cameras can capture 3D information of objects via single-shot imaging. However, for an underwater plenoptic camera, a waterproof spherical shell is needed to isolate the inner camera from the water, thus the performance of the overall imaging system will change due to the refractive effects of the waterproof and water medium. Accordingly, imaging properties like image clarity and field of view (FOV) will change. To address this issue, this paper proposes an optimized underwater plenoptic camera that compensates for the changes in image clarity and FOV. Based on the geometry simplification and the ray propagation analysis, the equivalent imaging process of each portion of an underwater plenoptic camera is modeled. To mitigate the impact of the FOV of the spherical shell and the water medium on image clarity, as well as to ensure successful assembly, an optimization model for physical parameters is derived after calibrating the minimum distance between the spherical shell and the main lens. The simulation results before and after underwater optimization are compared, which confirm the correctness of the proposed method. Additionally, a practical underwater focused plenoptic camera is designed, further demonstrating the effectiveness of the proposed model in real underwater scenarios.

[Design of broadband power divider in microwave hyperthermia system].

In clinical application of microwave hyperthermia, multi-applicators are often simultaneously required to irradiate the tumor because of its large volume or its deep location. Power divider separates the input microwave energy into equal, or unequal, energy to each applicator. In this paper, the design procedure for the three-section transmission-line transformer based one-to-two equal-split Wilkinson power divider is introduced. By impedance analysis on equivalent scheme, the design parameter of power divider is provided, and by simulation and optimization on Ansoft HFSS, a microstrip structure Wilkinson power divider operating frequency 2. 45 GHz is given. Measurement test results from network analyzer show that it has 25% bandwidth and good isolation in output with this structure. Besides, it is characterized by small size and easy processing. This power divider suits microwave hyperthermia.

A subject-specific finite element model of the anterior cruciate ligament.

The anterior cruciate ligament (ACL) is commonly injured. The stress distribution in the ACL is the key for understanding its function and injury mechanism, as well as for developing optimal surgical reconstruction protocols. In this study, a three-dimensional subject-specific finite element model of human ACL was developed. Bony geometries were reconstructed from CT scan images, while the geometry of the ACL and the orientation of its fiber bundles were measured via a mechanical digitizer. A transversely isotropic, hyperelastic, and nearly incompressible constitutive model was implemented to describe the mechanical properties of the ACL. A 134N anterior tibial load were applied to a cadaveric knee specimen at full extension, 30 degrees , and 60 degrees of flexion by a 6-DOF Robotic/Universal Force-moment Sensor (UFS) system, which was also used to measure the ACL resultant force. Knee kinematics was collected by digitizing two registration blocks attached to the femur and the tibia, respectively, and was input into the FE model as boundary conditions. The resultant force of the ACL calculated by the FE model was comparable to the experimental data, with the error within 10%, thus validated the model. The FE results showed that the average stress in the ACL was between the range 4.7-5.0MPa, with a peak stress between the range 9.8-10.9MPa, which shifted from the posterior lateral (PL) bundle to the anterior medial (AM) bundle as the knee flexed.

The effects of geometry and fiber bundle orientation on the finite element modeling of the anterior cruciate ligament.

The anterior cruciate ligament (ACL) has irregular geometry and spirally oriented fiber bundle organization, which are closely related to its physiological function. In previous finite element (FE) models, however, these two features are neglected due to the difficulty of obtaining its complex geometry and spiral fiber bundle orientation. Based on a previously developed and validated FE model, this study performed parametric studies to evaluate the effects of geometry and fiber bundle orientation on the FE modeling of the ACL. To evaluate the effect of the geometry, two models were compared: 1) with realistic ACL geometry obtained by using digitizer; 2) with ACL geometry reconstructed by directly connecting the femur and tibia insertion sites as commonly used in previous studies. To evaluate the effect of fiber bundle orientation, another two models were compared: 1) with realistic fiber bundle orientation obtained by using digitizer (alpha=38 degrees ); 2) with unrealistic fiber bundle orientation (alpha=0 degrees ). The same kinematics obtained by a Robotic/Universal Force-moment Sensor (UFS) system was input into the models as boundary conditions. The resultant forces calculated by the models were compared to the experimental data. The model with unrealistic geometry had a 40% higher ACL resultant force compared to the experimental data, while the model with the realistic ACL geometry well predicted the ACL resultant force, with an error less than 10%. When evaluating the effect of fiber bundle orientation, the model with unrealistic fiber bundle orientation predicted similar ACL resultant forces and stress distribution as the model with realistic fiber bundle orientation. The results revealed that ACL geometry has a significant effect on the FE model while fiber orientation does not.

The characteristics of metabolic activity based on regularization method.

The temperature recovering curve derived by cold stimulation experiment reveals human inner metabolism status. The errors of the measured data should be eliminated. A Tikhonov regularization method is used in this study to regularize the original data. The results present that the ability of body metabolic function can be measured by the temperature derivative curve, especially the characteristics in the first stage. Two typical shapes of these derived curves reflect the difference of two kinds of blood vessels in clinic. These temperature derivative curves oscillate generally in the last stage.

Interactive exhibition of human meridian based on Cult3D.

Acupuncture is the kernel of traditional Chinese medicine and is nowadays being accepted by the whole world. The precise orientation of the points and meridian is important in acupuncture while it is difficult to be done via the 2-dimension pictures. So the 3D interactive exhibition is undoubtedly superior to the traditional 2D way. A Web3D technology Cult3D and its advantages in contrast to VRML are presented. The implementation process of interactive human point exhibition by using Cult3D is discussed in detail. A primary attempt of expressing the knowledge system of meridian more intuitionisticly is made.

Facial expression recognition using thermal image.

Facial expression recognition will be studied in this paper using mathematics morphology, through drawing and analyzing the whole geometry characteristics and some geometry characteristics of the interesting area of Infrared Thermal Imaging (IRTI). The results show that geometry characteristic in the interesting region of different expression are obviously different; Facial temperature changes almost with the expression at the same time. Studies have shown feasibility of facial expression recognition on the basis of IRTI. This method can be used to monitor the facial expression in real time, which can be used in auxiliary diagnosis and medical on disease.

The separation of metabolizing heat based on independent component analysis.

The inner metabolizing status can be measured by surface temperature changes of human. These changes involve lots of heat influence in which metabolic heat-production is the most important. Based on processing the data acquired by improved cold stimulation experiment with Independent Component Analysis(ICA), this paper obtains two of main heat component - heat transfer quantity of blood perfusion and heat-production quantity of metabolism. The physiological meaning of these two components is discussed.

Analysis of human thermo response using 2nd order simulation circuit.

It is an important in bio-medical field to use a simulation technique which explain the bio-process in human body, heat transfer is one of human mechanical behavior. This paper emphasize on simulate the Bio-heat transfer mechanism in the human body by a 2nd order electro-circuit, then study and analyze the human heat response under different conditions.

A Correction Method of Medical Thermography's Distortion.

A problem of temperature distortion of medical thermography of the limb ending which results from different infrared radiant intensity of points detected by infrared detector was discussed. Further the difference of the radiant intensity is caused by that of projecting angles of points. Subsequently through related theory and experiments this paper found that the temperature shown by thermography bears a Gauss attenuation relation to actual surface temperature of an object. A Gaussian Matching Arithmetic was put forward to correct this kind of temperature distion. Finally, by using this Arithmetic a temperature distortion of thermography of a finger was corrected and the results were exciting.

Fundamental theoretic research of thermal texture maps I--simulation and analysis of the relation between the depth of inner heat source and surface temperature distribution in isotropy tissue.

Thermal texture maps is a new technology that can locate the inner abnormal heat sources of human by thermography analysis, and a great deal of application examples in clinic to early detect breast cancer with it shows its effectiveness. But the current explanation for its principle is hard to comprehensive and did not illuminate clearly the relation between the inner heat source and surface temperature distribution. In this paper, the temperature fields caused by the point heat source in isotropy tissue are simulated in different conditions, including different heat source intensities, different heat transfer coefficients and different heat depths and so on. The variation of surface temperature with the heat source depth change is discussed especially. The analysis result of simulation data shows that there lies the special relation between the heat source depth and the surface temperature distribution.

A circuit simulating method for heat transfer mechanism in human body.

It is a complicated process to produce the inner body heat and transfer the thermal energy to body surface. Based on the comparison between bio-heat transfer and current flow in circuit, this paper offers a method to analyze heat transfer mechanism using cold water to stimulate the body system to produce echo, and applying electrical components to build a circuit to simulate the process. This method considers the production of inner heat source, the influence of organism medium during inner thermal energy transfer to the body surface and the environment temperature. It is a primary attempt to evaluate the distribution of inner body temperature noninvasively by means of thermographs and provides a new way to analyze bio-heat transfer.

Analysis for fMRI feature of anxiety disorder patient by language stimulation.

The related studies have show that anxious disorder (AD) is associated with two factors: psychogenic and organic origin. In this study, using the functional magnetic resonance imaging (fMRI), we detect the responses in interrelated brain regions to different categories of auditory stimulation. The mathematic modeling was modeled according to the response data acquired, in order to study the correlative quantificational feature between the psychogenic stimulus and organic response. Then, the study tries to get a way to predict AD. In the further study, this research is helpful to study the pathogenesis of AD, diagnose AD in clinic and estimate the curative effect.