CHMM Object Detection Based on Polygon Contour Features by PSM

Since the conventional split–merge algorithm is sensitive to the object scale variance and splitting starting point, a piecewise split–merge polygon-approximation method is proposed to extract the object contour features. Specifically, the contour corner is used as the starting point for the contour piecewise approximation to reduce the sensitivity of the contour segment for the starting point; then, the split–merge algorithm is used to implement the polygon approximation for each contour segment. Both the distance ratio and the arc length ratio instead of the distance error are used as the iterative stop condition to improve the robustness to the object scale variance. Both the angle and length as two features describe the shape of the contour polygon; they have a strong coupling relationship since they affect each other along the contour order relationship. To improve the description correction of the contour, these two features are combined to construct a Coupled Hidden Markov Model to detect the object by calculating the probability of the contour feature. The proposed algorithm is validated on ETHZ Shape Classes and INRIA Horses standard datasets. Compared with other contour-based object-detection algorithms, the proposed algorithm reduces the feature number and improves the object-detection rate

Kalman Filtering Algorithm for Systems with Stochastic Nonlinearity Functions, Finite-Step Correlated Noises, and Missing Measurements

The locally optimal filter is designed for a class of discrete-time systems subject to stochastic nonlinearity functions, finite-step correlated noises, and missing measurements. The multiplicative noises are employed to describe the random disturbances in the system model. The phenomena of missing measurements occur in a random way and the missing probability is characterized by Bernoulli distributed random variables with known conditional probabilities. Based on the projection theory, a class of Kalman-type locally optimal filter is constructed and the filtering error covariance matrix is minimized in the sense of minimum mean square error principle. Also, by solving the recursive matrix equation, we can obtain the filter gain. Finally, two examples are provided: one is a numerical example to illustrate the feasibility and effectiveness of the proposed filtering scheme; the other is to solve the problem of target estimation for a tracking system considering networked phenomena

Preparation of Recombinant Human Collagen III Protein Hydrogels with Sustained Release of Extracellular Vesicles for Skin Wound Healing

Existing treatment methods encounter difficulties in effectively promoting skin wound healing, making this a serious challenge for clinical treatment. Extracellular vesicles (EVs) secreted by stem cells have been proven to contribute to the regeneration and repair of wound tissue, but they cannot be targeted and sustained, which seriously limits their current therapeutic potential. The recombinant human collagen III protein (rhCol III) has the advantages of good water solubility, an absence of hidden viral dangers, a low rejection rate and a stable production process. In order to achieve a site-specific sustained release of EVs, we prepared a rhCol III hydrogel by cross-linking with transglutaminase (TGase) from Streptomyces mobaraensis, which has a uniform pore size and good biocompatibility. The release profile of the rhCol III-EVs hydrogel confirmed that the rhCol III hydrogel could slowly release EVs into the external environment. Herein, the rhCol III-EVs hydrogel effectively promoted macrophage changing from type M1 to type M2, the migration ability of L929 cells and the angiogenesis of human umbilical vein endothelial cells (HUVECs). Furthermore, the rhCol III-EVs hydrogel is shown to promote wound healing by inhibiting the inflammatory response and promoting cell proliferation and angiogenesis in a diabetic rat skin injury model. The reported results indicate that the rhCol III-EVs hydrogel could be used as a new biological material for EV delivery, and has a significant application value in skin wound healing