Aim To introduce a new method of adaptive shape optimization (ASOP) based on three-dimensional structure boundary strength and optimize an engine bearing cap with the method. Methods Using the normal substance's p...Aim To introduce a new method of adaptive shape optimization (ASOP) based on three-dimensional structure boundary strength and optimize an engine bearing cap with the method. Methods Using the normal substance's property of thermal expansion and cooling shrinkage,the load which is proportional to the difference between the nodes' stress and their respective objective stress were applied to the corresponding variable nodes on the boundary.The thermal load made the nodes whose stress is greater than their objective stress expand along the boundary's normal direction and the nodes whose stress is less than objec- tive stress shrink in the opposite direction , This process would repeat until the stress on the boundary nodes was converge to the objective stress. Results The satisfied results have been obtained when optimizing an engine bearing cap.The mass of the bearing cap is reduced to 55 percent of the total. Conclusion ASOP is an efficient,practical and reliable method which is suitable for optimizing the shape of the continuous structures.展开更多
The conventional finite-element（FE） method often uses a structured mesh, which is designed according to the user’s experience, and it is not sufficiently accurate and flexible to accommodate complex structures such...The conventional finite-element（FE） method often uses a structured mesh, which is designed according to the user’s experience, and it is not sufficiently accurate and flexible to accommodate complex structures such as dipping interfaces and rough topography. We present an adaptive FE method for 2.5D forward modeling of induced polarization（IP）. In the presented method, an unstructured triangulation mesh that allows for local mesh refinement and flexible description of arbitrary model geometries is used. Furthermore, the mesh refinement process is guided by dual error estimate weighting to bias the refinement towards elements that affect the solution at the receiver locations. After the final mesh is generated, the Jacobian matrix is used to obtain the IP response on 2D structure models. We validate the adaptive FE algorithm using a vertical contact model. The validation shows that the elements near the receivers are highly refined and the average relative error of the potentials converges to 0.4 % and 1.2 % for the IP response. This suggests that the numerical solution of the adaptive FE algorithm converges to an accurate solution with the refined mesh. Finally, the accuracy and flexibility of the adaptive FE procedure are also validated using more complex models.展开更多
In contrast to the cries of human infants, sounds made by non-human infants in different stressful behavioral contexts （hunger or physical discomfort, isolation, capture by humans or predators） are usually treated a...In contrast to the cries of human infants, sounds made by non-human infants in different stressful behavioral contexts （hunger or physical discomfort, isolation, capture by humans or predators） are usually treated as distinct types of vocalizations. However, if distress vocalizations produced by different species and in different contexts share a common motivational state and associated neurochemical pathways, we can expect them to share a common acoustic structure and adaptive function, showing only limited variation that corresponds to the infant＇s level of arousal. Based on this premise, we review the acoustic structure and adaptive function of two types of distress calls, those given when infants were isolated from their mothers （isolation caUs） or captured by humans （capture calls）. We conducted a within-context comparison examining the two call types across a diverse se- lection of mammalian species and other vertebrate groups, followed by a comparison of how acoustic structure and function dif- fers between these contexts. In addition, we assessed acoustic traits that are critical to the response of caregivers. Across verte- brate species, distress vocalizations produced in these two behavioral contexts tend to be tonal with a simple chevron, flat or de- scending pattern of frequency modulation. Reports that both isolation and capture calls of vertebrate infants serve to attract care- givers are universal, and the fundamental frequency of infant vocalizations is often critical to this response. The results of our re- view are consistent with the hypothesis that differences in the acoustic structure of isolation and capture distress vocalizations re- flect differences in arousal, and not discrete functions. The similarity in acoustic structure and caregiver response observed across vertebrates adds support to the hypothesis that the production and processing of distress vocalizations are part of a highly-conserved system of social vocal behaviour in vertebrates. Bioacoustic research may move forward by recognizing the commonality among different forms of infant solicitations that attract caregivers, and the commonality of these solicitations with vocalizations that attract conspecifics in still other behavioral contexts [Current Zoology 58 （5）： 698-726, 2012].展开更多
文摘Aim To introduce a new method of adaptive shape optimization (ASOP) based on three-dimensional structure boundary strength and optimize an engine bearing cap with the method. Methods Using the normal substance's property of thermal expansion and cooling shrinkage,the load which is proportional to the difference between the nodes' stress and their respective objective stress were applied to the corresponding variable nodes on the boundary.The thermal load made the nodes whose stress is greater than their objective stress expand along the boundary's normal direction and the nodes whose stress is less than objec- tive stress shrink in the opposite direction , This process would repeat until the stress on the boundary nodes was converge to the objective stress. Results The satisfied results have been obtained when optimizing an engine bearing cap.The mass of the bearing cap is reduced to 55 percent of the total. Conclusion ASOP is an efficient,practical and reliable method which is suitable for optimizing the shape of the continuous structures.
基金financially supported by the National Natural Science Foundation of China(No.41204055,41164003,and 41104074)Opening Project(No.SMIL-2014-06) of Hubei Subsurface Multi-scale Imaging Lab(SMIL),China University of Geosciences(Wuhan)
文摘The conventional finite-element（FE） method often uses a structured mesh, which is designed according to the user’s experience, and it is not sufficiently accurate and flexible to accommodate complex structures such as dipping interfaces and rough topography. We present an adaptive FE method for 2.5D forward modeling of induced polarization（IP）. In the presented method, an unstructured triangulation mesh that allows for local mesh refinement and flexible description of arbitrary model geometries is used. Furthermore, the mesh refinement process is guided by dual error estimate weighting to bias the refinement towards elements that affect the solution at the receiver locations. After the final mesh is generated, the Jacobian matrix is used to obtain the IP response on 2D structure models. We validate the adaptive FE algorithm using a vertical contact model. The validation shows that the elements near the receivers are highly refined and the average relative error of the potentials converges to 0.4 % and 1.2 % for the IP response. This suggests that the numerical solution of the adaptive FE algorithm converges to an accurate solution with the refined mesh. Finally, the accuracy and flexibility of the adaptive FE procedure are also validated using more complex models.
文摘In contrast to the cries of human infants, sounds made by non-human infants in different stressful behavioral contexts （hunger or physical discomfort, isolation, capture by humans or predators） are usually treated as distinct types of vocalizations. However, if distress vocalizations produced by different species and in different contexts share a common motivational state and associated neurochemical pathways, we can expect them to share a common acoustic structure and adaptive function, showing only limited variation that corresponds to the infant＇s level of arousal. Based on this premise, we review the acoustic structure and adaptive function of two types of distress calls, those given when infants were isolated from their mothers （isolation caUs） or captured by humans （capture calls）. We conducted a within-context comparison examining the two call types across a diverse se- lection of mammalian species and other vertebrate groups, followed by a comparison of how acoustic structure and function dif- fers between these contexts. In addition, we assessed acoustic traits that are critical to the response of caregivers. Across verte- brate species, distress vocalizations produced in these two behavioral contexts tend to be tonal with a simple chevron, flat or de- scending pattern of frequency modulation. Reports that both isolation and capture calls of vertebrate infants serve to attract care- givers are universal, and the fundamental frequency of infant vocalizations is often critical to this response. The results of our re- view are consistent with the hypothesis that differences in the acoustic structure of isolation and capture distress vocalizations re- flect differences in arousal, and not discrete functions. The similarity in acoustic structure and caregiver response observed across vertebrates adds support to the hypothesis that the production and processing of distress vocalizations are part of a highly-conserved system of social vocal behaviour in vertebrates. Bioacoustic research may move forward by recognizing the commonality among different forms of infant solicitations that attract caregivers, and the commonality of these solicitations with vocalizations that attract conspecifics in still other behavioral contexts [Current Zoology 58 （5）： 698-726, 2012].
