The biomechanical changes during functional loading and unloading of the human gastrointestinal (GI) tract are not fully understood. GI function is usually studled by introducing probes in the GI lumen. Computer mod...The biomechanical changes during functional loading and unloading of the human gastrointestinal (GI) tract are not fully understood. GI function is usually studled by introducing probes in the GI lumen. Computer modeling offers a promising alternative approach in this regard, with the additional ability to predict regional stresses and strains in inaccessible locations. The tension and stress distributions in the GI tract are related to distensibility (tension-strain relationship) and smooth muscle tone. lore knowledge on the tension and stress on the GI tract are needed to improve diagnosis of patients with gastrointestinal disorders. A modeling framework that can be used to integrate the physiological, anatomical and medical knowledge of the GI system has recently been developed. The 3-D anatomical model was constructed from digital images using ultrasonography, computer tomography (CT) or magnetic resonance imaging (IRI). Different mathematical algorithms were developed for surface analysis based on thin-walled structure and the finite element method was applied for the mucosa-folded three layered esophageal model analysis. The tools may be useful for studying the geometry and biomechanical properties of these organs in health and disease. These studies will serve to test the structurefunction hypothesis of geometrically complex organs.展开更多
Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.Th...Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.The multichannel audio is represented with 3-order tensor space and is decomposed into core tensor with three factor matrices in the way of channel,time and frequency.Only the truncated core tensor is transmitted which will be multiplied by the pre-trained factor matrices to reconstruct the original tensor space.Objective and subjective experiments have been done to show a very noticeable compression capability with an acceptable output quality.The novelty of the proposed compression method is that it enables both high compression capability and backward compatibility with limited signal distortion to the hearing.展开更多
This paper proposes a novel dynamic control approach for a cable-driven robot with high redundant actuation and cable tension limitations to perform tracking task while interacting with environment. In order for a cab...This paper proposes a novel dynamic control approach for a cable-driven robot with high redundant actuation and cable tension limitations to perform tracking task while interacting with environment. In order for a cable-driven exoskeleton robot to execute the task smoothly and safely, it is necessary to consider the tracking motion performance as well as passivity when interacting with the environment under the conditions of the actuation cables' redundancy and the pulling limitation. With the additional consideration of the maximum limitation of the cable tension, cable-driven robot actually can only apply a certain range of feasible wrench on the external environment, which makes the task executed by robot be restricted. In order to make designed wrench be feasible and keep the desired trajectory tracking ability, we present a new control method by extending PVFC (passive velocity field control) method considering tracking stability and passivity. The approach augmented a higher dimensional virtual flywheel dynamics in a specific orthogonal complement space of the cable's actuation space. After the final adjustment of the designed wrench with respect to the cable's constraint, this method is capable of driving the cable robot to complete the trajectory tracking task and realize the passivity.展开更多
Since the mid-twentieth century, most cities worldwide have undergone a rapid expansion in urban land use. Along with the expansion, several problems, such as excessive loss of prime agricultural land and increasing t...Since the mid-twentieth century, most cities worldwide have undergone a rapid expansion in urban land use. Along with the expansion, several problems, such as excessive loss of prime agricultural land and increasing traffic congestion have arisen. Thus, understanding and measurements of the expansion scale and its speed are crucial to planners and officials during urban planning and management processes. To measure such geographic phenomena, Shannon first devised entropy theory, and then Batty developed it into spatial entropy. The recently developed spatial entropy model, which was used to measure urban sprawl, introduced area to represent spatial asymmetry. However, most models did not consider spatial discretization, particularly the impact of distance. This study attempted to construct an integrated gravity-spatial entropy model to delineate distance and spatial diffusion impacts on population distribution. Then, we tested the model using Shanghai's temporal land use and community statistical data. Application results for the new gravity-spatial model show that it is a useful tool for identifying spatial and temporal variations of urban sprawl.展开更多
文摘The biomechanical changes during functional loading and unloading of the human gastrointestinal (GI) tract are not fully understood. GI function is usually studled by introducing probes in the GI lumen. Computer modeling offers a promising alternative approach in this regard, with the additional ability to predict regional stresses and strains in inaccessible locations. The tension and stress distributions in the GI tract are related to distensibility (tension-strain relationship) and smooth muscle tone. lore knowledge on the tension and stress on the GI tract are needed to improve diagnosis of patients with gastrointestinal disorders. A modeling framework that can be used to integrate the physiological, anatomical and medical knowledge of the GI system has recently been developed. The 3-D anatomical model was constructed from digital images using ultrasonography, computer tomography (CT) or magnetic resonance imaging (IRI). Different mathematical algorithms were developed for surface analysis based on thin-walled structure and the finite element method was applied for the mucosa-folded three layered esophageal model analysis. The tools may be useful for studying the geometry and biomechanical properties of these organs in health and disease. These studies will serve to test the structurefunction hypothesis of geometrically complex organs.
基金This work was partially supported by the National Natural Science Foundation of China under Grants No.11161140319,No.61001188,the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20101101110020,the Fund for Basic Research from Beijing Institute of Technology under Grant No.20120542011,the Fund for Beijing Higher Education Young Elite Teacher Project under Grant No.YETP1202
文摘Multichannel audio signal is more difficult to be compressed than mono and stereo ones.A novel multichannel audio signal compression method based on tensor representation and decomposition is proposed in this paper.The multichannel audio is represented with 3-order tensor space and is decomposed into core tensor with three factor matrices in the way of channel,time and frequency.Only the truncated core tensor is transmitted which will be multiplied by the pre-trained factor matrices to reconstruct the original tensor space.Objective and subjective experiments have been done to show a very noticeable compression capability with an acceptable output quality.The novelty of the proposed compression method is that it enables both high compression capability and backward compatibility with limited signal distortion to the hearing.
基金This research has been partially supported by National Natural Science Foundation of China under Grant No. 61472117.
文摘This paper proposes a novel dynamic control approach for a cable-driven robot with high redundant actuation and cable tension limitations to perform tracking task while interacting with environment. In order for a cable-driven exoskeleton robot to execute the task smoothly and safely, it is necessary to consider the tracking motion performance as well as passivity when interacting with the environment under the conditions of the actuation cables' redundancy and the pulling limitation. With the additional consideration of the maximum limitation of the cable tension, cable-driven robot actually can only apply a certain range of feasible wrench on the external environment, which makes the task executed by robot be restricted. In order to make designed wrench be feasible and keep the desired trajectory tracking ability, we present a new control method by extending PVFC (passive velocity field control) method considering tracking stability and passivity. The approach augmented a higher dimensional virtual flywheel dynamics in a specific orthogonal complement space of the cable's actuation space. After the final adjustment of the designed wrench with respect to the cable's constraint, this method is capable of driving the cable robot to complete the trajectory tracking task and realize the passivity.
基金the Fundamental Research Funds for the Central Universities (Grant No. 2572014CB20)Heilongjiang Province Postdoctoral Science Foundation (Grant No. LBH-Z10279)the Scientific Research Foundation for Returned Overseas Chinese Scholars, Heilongjiang Province (Grant No. LC2013C13)
文摘Since the mid-twentieth century, most cities worldwide have undergone a rapid expansion in urban land use. Along with the expansion, several problems, such as excessive loss of prime agricultural land and increasing traffic congestion have arisen. Thus, understanding and measurements of the expansion scale and its speed are crucial to planners and officials during urban planning and management processes. To measure such geographic phenomena, Shannon first devised entropy theory, and then Batty developed it into spatial entropy. The recently developed spatial entropy model, which was used to measure urban sprawl, introduced area to represent spatial asymmetry. However, most models did not consider spatial discretization, particularly the impact of distance. This study attempted to construct an integrated gravity-spatial entropy model to delineate distance and spatial diffusion impacts on population distribution. Then, we tested the model using Shanghai's temporal land use and community statistical data. Application results for the new gravity-spatial model show that it is a useful tool for identifying spatial and temporal variations of urban sprawl.