On the stability of surface shape reconstruction using microwave algorithm for 3-D breast tumor based on the adjoint-fields scheme

Author(s):  
Magda El-Shenawee ◽  
Miguel Moscoso ◽  
Oliver Dorn
Author(s):  
Linbo Zhu ◽  
Yifei Hou ◽  
Abdel-Hakim Bouzid ◽  
Jun Hong

Metal to metal contact between joint surfaces is widely used in bolted joints to obtain a rigid and a high performance connection. However, a significant amount of clamping load is lost when the joint is subjected to mechanical and thermal loading including creep and fatigue. In practice, to prevent bolt loosening, additional parts such as spring washers, double nut, spring lock washers, Nyloc nut and so on are used. Those methods are costly and influence the stability of the joint and affect its structural integrity. It is well established that a small compression displacement in clamping parts leads to a big clamping load loss in stiff joints. This paper discusses the relationship between connection stiffness and clamping load and presents a method that improves clamping load retention during operation by a careful design of the member contact surface shape. A single bolted joint with two clamping parts is modeled using finite element method (FEM). A method is proposed to obtain a specific stiffness by an optimized geometrical shape of the joint contact surfaces. The result shows that the contact surface shape based on a gradually varying gap can improve the retention of the initial clamping load. Furthermore, a formula of the connection stiffness based on the curve fitting technique is proposed to predict residual clamping load under different external load and loosening.


Author(s):  
Kui Wang ◽  
Chi Hin Mak ◽  
Justin Di-Lang Ho ◽  
Zhi-Yu Liu ◽  
Kam Yim Sze ◽  
...  

Proprioception, the ability to perceive one’s own configuration and movement in space, enables organisms to safely and accurately interact with their environment and each other. The underlying sensory nerves that make this possible are highly dense and use sophisticated communication pathways to propagate signals from nerves in muscle, skin and joints to the central nervous system wherein the organism can process and react to stimuli. In a step forward to realize robots with such perceptive capability, we propose a flexible sensor framework that incorporates a novel hybrid modeling strategy, taking advantage of computational mechanics and machine learning. We implement the sensor framework on a large, thin and flexible sensor that transforms sparsely distributed strains into continuous surface shape. Finite element (FE) analysis is utilized to determine sensor design parameters, while an FE model is built to enrich the morphological data used in the supervised training to achieve continuous surface reconstruction. A mapping between the local strain data and the enriched surface data is subsequently trained using ensemble learning. This hybrid approach enables real-time, robust and high-order surface shape reconstruction. The sensing performance is evaluated in terms of accuracy, repeatability, and feasibility with numerous scenarios, which has not been demonstrated and reported on such a large-scale (A4-paper-size) sensor before.


2012 ◽  
Vol 20 (27) ◽  
pp. 28341 ◽  
Author(s):  
Antonin Miks ◽  
Jiri Novak

2012 ◽  
Vol 170-173 ◽  
pp. 1158-1161
Author(s):  
Sen Wen ◽  
Li Min Zhao ◽  
Yu Qing Yuan

The research on slope is concentrated on stability analysis at present. Although there is little research on slope surface shape, it has important theoretical and practical significance. Based on guaranteeing the same earthwork, the shape of slope surfaces between single gradient slope surface and two-gradient slope surface whose lower part is steeper than upper part are compared. It’s concluded that (1) based on guaranteeing the same earthwork, two-gradient slope surface, whose lower part is steeper than upper part, is stabler than single gradient slope surface and when the lower part is vertical wall, the slope is stablest; (2) the height of vertical wall has a knee point, i.e. when more than this value ,the stability of slope decreases.


Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 814
Author(s):  
Kena Song ◽  
Xiangyang Zu ◽  
Zhe Du ◽  
Zhigang Hu ◽  
Jingjing Wang ◽  
...  

Breast disease is one of the critical diseases that plague females, as is known, breast cancer has high mortality, despite significant pathophysiological progress during the past few years. Novel diagnostic and therapeutic approaches are needed to break the stalemate. An organ-on-chip approach is considered due to its ability to repeat the real conditions found in the body on microfluidic chips, offsetting the shortcomings of traditional 2D culture and animal tests. In recent years, the organ-on-chip approach has shown diversity, recreating the structure and functional units of the real organs/tissues. The applications were also developed rapidly from the laboratory to the industrialized market. This review focuses on breast tumor-on-a-chip approaches concerning the diversity models and applications. The models are summarized and categorized by typical biological reconstitution, considering the design and fabrication of the various breast models. The breast tumor-on-a-chip approach is a typical representative of organ chips, which are one of the precedents in the market. The applications are roughly divided into two categories: fundamental mechanism research and biological medicine. Finally, we discuss the prospect and deficiencies of the emerging technology. It has excellent prospects in all of the application fields, however there exist some deficiencies for promotion, such as the stability of the structure and function, and uniformity for quantity production.


Author(s):  
Kui Wang ◽  
Chi Hin Mak ◽  
Justin Di-Lang Ho ◽  
Zhi-Yu Liu ◽  
Kam Yim Sze ◽  
...  

Proprioception, the ability to perceive one’s own configuration and movement in space, enables organisms to safely and accurately interact with their environment and each other. The underlying sensory nerves that make this possible are highly dense and use sophisticated communication pathways to propagate signals from nerves in muscle, skin and joints to the central nervous system wherein the organism can process and react to stimuli. In a step forward to realize robots with such perceptive capability, we propose a flexible sensor framework that incorporates a novel hybrid modeling strategy, taking advantage of computational mechanics and machine learning. We implement the sensor framework on a large, thin and flexible sensor that transforms sparsely distributed strains into continuous surface shape. Finite element (FE) analysis is utilized to determine sensor design parameters, while an FE model is built to enrich the morphological data used in the supervised training to achieve continuous surface reconstruction. A mapping between the local strain data and the enriched surface data is subsequently trained using ensemble learning. This hybrid approach enables real-time, robust and high-order surface shape reconstruction. The sensing performance is evaluated in terms of accuracy, repeatability, and feasibility with numerous scenarios, which has not been demonstrated and reported on such a large-scale (A4-paper-size) sensor before.


2018 ◽  
Vol 63 (9) ◽  
pp. 777
Author(s):  
M. V. Vavrukh ◽  
D. V. Dzikovskyi ◽  
S. V. Smerechynskyi

Using the equation of state of the electron-nuclear model at high densities and the mechanical equilibrium equation, we have investigated the influence of interparticle interactions and the axial rotation on the macroscopic characteristics (mass, surface shape) of massive degenerate dwarfs. We propose a method of solving the equilibrium equation in the case of rotation that uses the basis of universal functions of the radial variable. The conditions, under which the axial rotation can compensate for a weight loss of the mass due to the Coulomb interactions, have been established. The maximal value of the relativistic parameter, at which the stability is disturbed, is determined within the general theory of relativity (GTR).


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Danqing Zhang ◽  
Binbin Xiang ◽  
Aili Yusup ◽  
Na Wang ◽  
Guljaina Kazezkhan

The QiTai Radio Telescope (QTT) will be equipped with the active surface adjustment system (ASAS) to correct the main reflector deformation caused by environmental loading. In order to guarantee the stability and performance of the active surface system under fault conditions, it is necessary to adopt the fault-tolerant method when actuator faults have occurred. In this paper, a fault control method based on actuator faults weighting is proposed to solve the active surface fault control problem. According to the coordinates of the adjustable points of the panels corresponding to the faulty actuators, a new paraboloid is fitted by a weighted health matrix, and the fitting surface is taken as the target to adjust the surface shape.


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