Journal articles on the topic 'Poisson robotisé'
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1
Hasse, Alexander, and Kristian Mauser. "Poisson Induced Bending Actuator for Soft Robotic Systems." Soft Robotics 7, no. 2 (April 1, 2020): 155–67. http://dx.doi.org/10.1089/soro.2018.0163.
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Schiemer, Jonas F., Karen Stumm, Karin H. Somerlik-Fuchs, Klaus-Peter Hoffmann, Jan Baumgart, and Werner Kneist. "Robotic Setup Promises Consistent Effects of Multilocular Gastrointestinal Electrical Stimulation: First Results of a Porcine Study." European Surgical Research 61, no. 1 (2020): 14–22. http://dx.doi.org/10.1159/000506799.
Abstract:
Background: Electrical stimulation (ES) of several gastrointestinal (GI) segments is a promising therapeutic option for multilocular GI dysmotility, but conventional surgical access by laparotomy involves a high degree of tissue trauma. We evaluated a minimally invasive surgical approach using a robotic surgical system to perform electromyographic (EMG) recordings and ES of several porcine GI segments, comparing these data to an open surgical approach by laparotomy. Materials and Methods: In 5 acute porcine experiments, we placed multiple electrodes on the stomach, duodenum, jejunum, ileum, and colon. Three experiments were performed with a median laparotomy and 2 others using a robotic platform. Multichannel EMGs were recorded, and ES was sequentially delivered with 4 ES parameters to the 5 target segments. We calculated pre- and poststimulatory spikes per minute (Spm) and performed a statistical Poisson analysis. Results: Electrode placement was achieved in all cases without complications. Increased technical and implantation time were required to achieve the robotic electrode placement, but invasiveness was markedly reduced in comparison to the conventional approach. The highest calculated (c)Spm values were found in the poststimulatory period of the small bowel with both the conventional and robotic approaches. Six of the 20 Poisson test results in the open setup reached statistical significance and 12 were significant in the robotic experiments. Conclusions: The robotic setup was less invasive, revealed more consistent effects of multilocular ES in several GI segments, and is a promising option for future preclinical and clinical studies of GI motility disorders.
3
Refaai, Mohamad Reda A., M. N. Manjunatha, S. Radjarejesri, B. Ramesh, Ram Subbiah, and Nahom Adugna. "Nanorobots with Hybrid Biomembranes for Simultaneous Degradation of Toxic Microorganism." Advances in Materials Science and Engineering 2022 (September 23, 2022): 1–12. http://dx.doi.org/10.1155/2022/2391843.
Abstract:
Nanorobotics is a modern technological sector that creates robots with elements that are close to or near the nanoscale scale of such a nanometer. To be more specific, nanorobotics has been the nanotechnology approach to designing and creating nanorobots. Also, with the fast growth of robotics technology, developing biomaterials micro- or nanorobots, which convert biological concepts into a robotic device, grows progressively vital. This proposes the development, manufacturing, and testing of a dual–cell membrane–functionalized nanorobot for multifunctional biological threat component elimination, with a focus on the simultaneous targeted and neutralization of the pathogenic bacteria and toxins. Ultrasound-propelled biomaterials nanorobots comprised of the gold nanostructures wrapped in a combination of platelet (PL) and Red Blood Cell (RBC) layers were developed. Biohybrid micro- and nanorobots were small machines that combine biological and artificial elements. They may benefit from onboard actuators, detection, management, and deployment of a variety in medical functions. These hybrid cell walls consist of a variety of structural proteins involved in living organism RBCs and PLs, which provide nanorobots with either a quantity of the appealing biological functionality, with bonding and adhesion to the PL-adhering pathogenic organisms (for example, staphylococcus bacteria) but also neutralization of the pore-forming toxins (e.g., toxin). Furthermore, the biomaterials nanorobots demonstrated quick and efficient extended sonic propulsion for total blood with really no visible bacterial growth and mirrored the movements of genuine cell separation. This propulsion improved the robots’ bonding and detoxifying efficacy against infections and poisons. Overall, combining this diversified physiological activity of hybrid cellular tissue with the energy propulsion of such robotic systems contributed to the dynamic robotics scheme for effective separation and synchronous elimination of various living risks, a significant step towards to development of a broad-spectrum detoxifying robotic framework.
4
Watson, Michael D., Sally J. Trufan, Nicole L. Gower, Joshua S. Hill, and Jonathan C. Salo. "Effect of Surgical Approach on Node Harvest in Robotic Gastrectomy." American Surgeon 85, no. 8 (August 2019): 794–99. http://dx.doi.org/10.1177/000313481908500827.
Abstract:
There has been increasing utilization of minimally invasive surgical approaches. This study evaluates the effect of surgical approach on total lymph node harvest in gastrectomy. Patients undergoing gastrectomy for gastric adenocarcinoma between 2007 and 2018 were reviewed retrospectively. Data collected included age, gender, race, BMI, neoadjuvant therapy, tumor stage, surgical approach, and total number of lymph nodes harvested. The total number of harvested lymph nodes for open, laparoscopic, and robotic gastrectomy was compared using the Kruskal-Wallis test for univariate analysis and a Poisson regression model for multivariable analysis. One hundred four patients were identified. Median node harvest for open, laparoscopic, and robotic approaches were 16, 17, and 36, respectively. Multivariable analysis controlling for gender, BMI, pathological T stage, and year of operation demonstrates that surgical approach is statistically significantly associated with lymph node harvest ( F = 83.4, P < 0.0001). In multivariable analysis, robotic approach was associated with greater lymph node harvest than both open ( P < 0.0001) and laparoscopic ( P < 0.0001) approaches, whereas laparoscopic approach was associated with greater lymph node harvest than open ( P < 0.0001) approach. These data demonstrate that for patients undergoing gastrectomy for gastric adenocarcinoma at our institution, robotic approach is associated with greater lymph node harvest than both laparoscopic and open approaches.
5
Liu, Wangyu, Zheng Liu, Zhengqiang Guo, Zhaoqi Chen, and Weigui Xie. "Application of Poisson’s ratio structures and decoupling algorithm for 3D force sensing." Measurement Science and Technology 35, no. 6 (March 12, 2024): 065105. http://dx.doi.org/10.1088/1361-6501/ad3018.
Abstract:
Abstract Flexible tactile electronic devices are extensively used in the fields of robotics, medical detection, and human-computer interaction. Monitoring contact parameters, including force magnitude, direction, and contact location, is particularly vital for skin-like tactile sensing devices. Herein, a 3D force sensor is designed based on porous structure with deliberately designed Poisson’s ratios. A genetic algorithm (GA) optimized back propagation neuronal network (BPNN) model is proposed to support the 3D force decoupling, which can greatly improve the decoupling accuracy. The introduction of the GA-BPNN significantly enhances decoupling accuracy compared to the initial neural network. Micro-porous structures with varied Poisson’s ratios are embedded into the sensing unit to achieve better sensibility. Significantly, this study underscores that the decoupling accuracy of the force components along the Z-axis can be further improved by substituting the solid unit with a designed porous structure unit featuring a specific Poisson’s ratio in an arrayed 3D force sensor.
6
Vázquez-Arellano, Manuel, David Reiser, Dimitrios Paraforos, Miguel Garrido-Izard, and Hans Griepentrog. "Leaf Area Estimation of Reconstructed Maize Plants Using a Time-of-Flight Camera Based on Different Scan Directions." Robotics 7, no. 4 (October 11, 2018): 63. http://dx.doi.org/10.3390/robotics7040063.
Abstract:
The leaf area is an important plant parameter for plant status and crop yield. In this paper, a low-cost time-of-flight camera, the Kinect v2, was mounted on a robotic platform to acquire 3-D data of maize plants in a greenhouse. The robotic platform drove through the maize rows and acquired 3-D images that were later registered and stitched. Three different maize row reconstruction approaches were compared: reconstruct a crop row by merging point clouds generated from both sides of the row in both directions, merging point clouds scanned just from one side, and merging point clouds scanned from opposite directions of the row. The resulted point cloud was subsampled and rasterized, the normals were computed and re-oriented with a Fast Marching algorithm. The Poisson surface reconstruction was applied to the point cloud, and new vertices and faces generated by the algorithm were removed. The results showed that the approach of aligning and merging four point clouds per row and two point clouds scanned from the same side generated very similar average mean absolute percentage error of 8.8% and 7.8%, respectively. The worst error resulted from the two point clouds scanned from both sides in opposite directions with 32.3%.
7
Kazerooni, H., Mark S. Evans, and J. Jones. "Hydrostatic Force Sensor for Robotic Applications." Journal of Dynamic Systems, Measurement, and Control 119, no. 1 (March 1, 1997): 115–19. http://dx.doi.org/10.1115/1.2801201.
Abstract:
This article presents a theoretical and experimental investigation of a new kind of force sensor which detects forces by measuring an induced pressure change in a material of large Poisson’s ratio. In this investigation, we develop mathematical expressions for the sensor’s sensitivity and bandwidth, and show that its sensitivity can be much larger and its bandwidth is usually smaller than those of existing strain-gage-type sensors. This force sensor is well-suited for measuring large but slowly varying forces. It can be installed in a space smaller than that required for existing sensors. This paper also discusses the effects of various parameters on the sensor’s performance and on failure modes. To verify the theoretical derivation, a prototype force sensor was designed and built. This prototype hydrostatic force sensor can measure the compressive forces up to 7200 lbf and tensile forces up to 3500 lbf.
8
Serpen, Gursel, and Jayanta Debnath. "Design and performance evaluation of a parking management system for automated, multi-story and robotic parking structure." International Journal of Intelligent Computing and Cybernetics 12, no. 4 (November 11, 2019): 444–65. http://dx.doi.org/10.1108/ijicc-02-2019-0017.
Abstract:
Purpose The purpose of this paper is to present design and performance evaluation through simulation of a parking management system (PMS) for a fully automated, multi-story, puzzle-type and robotic parking structure with the overall objective of minimizing customer wait times while maximizing the space utilization. Design/methodology/approach The presentation entails development and integration of a complete suite of path planning, elevator scheduling and resource allocation algorithms. The PMS aims to manage multiple concurrent requests, in real time and in a dynamic context, for storage and retrieval of vehicles loaded onto robotic carts for a fully automated, multi-story and driving-free parking structure. The algorithm suite employs the incremental informed search algorithm D* Lite with domain-specific heuristics and the uninformed search algorithm Uniform Cost Search for path search and planning. An optimization methodology based on nested partitions and Genetic algorithm is adapted for scheduling of a group of elevators. The study considered a typical business day scenario in the center of a metropolis. Findings The simulation study indicates that the proposed design for the PMS is able to serve concurrent storage-retrieval requests representing a wide range of Poisson distributed customer arrival rates in real time while requiring reasonable computing resources under realistic scenarios. The customer waiting times for both storage and retrieval requests are within acceptable bounds, which are set as no more than 5 min, even in the presence of up to 100 concurrent storage and retrieval requests. The design is able to accommodate a variety of customer arrival rates and presence of immobilized vehicles which are assumed to be scattered across the floors of the structure to make it possible for deployment in real-time environments. Originality/value The intelligent system design is novel as the fully automated robotic parking structures are just in the process of being matured from a technology standpoint.
9
Li, Yue, Stelian Coros, and Bernhard Thomaszewski. "Neural Metamaterial Networks for Nonlinear Material Design." ACM Transactions on Graphics 42, no. 6 (December 5, 2023): 1–13. http://dx.doi.org/10.1145/3618325.
Abstract:
Nonlinear metamaterials with tailored mechanical properties have applications in engineering, medicine, robotics, and beyond. While modeling their macromechanical behavior is challenging in itself, finding structure parameters that lead to ideal approximation of high-level performance goals is a challenging task. In this work, we propose Neural Metamaterial Networks (NMN)---smooth neural representations that encode the nonlinear mechanics of entire metamaterial families. Given structure parameters as input, NMN return continuously differentiable strain energy density functions, thus guaranteeing conservative forces by construction. Though trained on simulation data, NMN do not inherit the discontinuities resulting from topo-logical changes in finite element meshes. They instead provide a smooth map from parameter to performance space that is fully differentiable and thus well-suited for gradient-based optimization. On this basis, we formulate inverse material design as a nonlinear programming problem that leverages neural networks for both objective functions and constraints. We use this approach to automatically design materials with desired strain-stress curves, prescribed directional stiffness and Poisson ratio profiles. We furthermore conduct ablation studies on network nonlinearities and show the advantages of our approach compared to native-scale optimization.
10
Duits, Remco, Erik J. Bekkers, and Alexey Mashtakov. "Fourier Transform on the Homogeneous Space of 3D Positions and Orientations for Exact Solutions to Linear PDEs." Entropy 21, no. 1 (January 8, 2019): 38. http://dx.doi.org/10.3390/e21010038.
Abstract:
Fokker–Planck PDEs (including diffusions) for stable Lévy processes (including Wiener processes) on the joint space of positions and orientations play a major role in mechanics, robotics, image analysis, directional statistics and probability theory. Exact analytic designs and solutions are known in the 2D case, where they have been obtained using Fourier transform on S E ( 2 ) . Here, we extend these approaches to 3D using Fourier transform on the Lie group S E ( 3 ) of rigid body motions. More precisely, we define the homogeneous space of 3D positions and orientations R 3 ⋊ S 2 : = S E ( 3 ) / ( { 0 } × S O ( 2 ) ) as the quotient in S E ( 3 ) . In our construction, two group elements are equivalent if they are equal up to a rotation around the reference axis. On this quotient, we design a specific Fourier transform. We apply this Fourier transform to derive new exact solutions to Fokker–Planck PDEs of α -stable Lévy processes on R 3 ⋊ S 2 . This reduces classical analysis computations and provides an explicit algebraic spectral decomposition of the solutions. We compare the exact probability kernel for α = 1 (the diffusion kernel) to the kernel for α = 1 2 (the Poisson kernel). We set up stochastic differential equations (SDEs) for the Lévy processes on the quotient and derive corresponding Monte-Carlo methods. We verified that the exact probability kernels arise as the limit of the Monte-Carlo approximations.
11
Reid, Daniel R., Nidhi Pashine, Justin M. Wozniak, Heinrich M. Jaeger, Andrea J. Liu, Sidney R. Nagel, and Juan J. de Pablo. "Auxetic metamaterials from disordered networks." Proceedings of the National Academy of Sciences 115, no. 7 (January 30, 2018): E1384—E1390. http://dx.doi.org/10.1073/pnas.1717442115.
Abstract:
Recent theoretical work suggests that systematic pruning of disordered networks consisting of nodes connected by springs can lead to materials that exhibit a host of unusual mechanical properties. In particular, global properties such as Poisson’s ratio or local responses related to deformation can be precisely altered. Tunable mechanical responses would be useful in areas ranging from impact mitigation to robotics and, more generally, for creation of metamaterials with engineered properties. However, experimental attempts to create auxetic materials based on pruning-based theoretical ideas have not been successful. Here we introduce a more realistic model of the networks, which incorporates angle-bending forces and the appropriate experimental boundary conditions. A sequential pruning strategy of select bonds in this model is then devised and implemented that enables engineering of specific mechanical behaviors upon deformation, both in the linear and in the nonlinear regimes. In particular, it is shown that Poisson’s ratio can be tuned to arbitrary values. The model and concepts discussed here are validated by preparing physical realizations of the networks designed in this manner, which are produced by laser cutting 2D sheets and are found to behave as predicted. Furthermore, by relying on optimization algorithms, we exploit the networks’ susceptibility to tuning to design networks that possess a distribution of stiffer and more compliant bonds and whose auxetic behavior is even greater than that of homogeneous networks. Taken together, the findings reported here serve to establish that pruned networks represent a promising platform for the creation of unique mechanical metamaterials.
12
Khoshgoftar, Mohammad Javad, Ali Barkhordari, Sajjad Seifoori, and Mohammad Javad Mirzaali. "Elasticity Approach to Predict Shape Transformation of Functionally Graded Mechanical Metamaterial under Tension." Materials 14, no. 13 (June 22, 2021): 3452. http://dx.doi.org/10.3390/ma14133452.
Abstract:
The re-entrant structures are among the simple unit cell designs that have been widely used in the design of mechanical metamaterials. Changing the geometrical parameters of these unit cell structures, their overall elastic properties (i.e., elastic stiffness and Poisson’s ratio), can be simultaneously tuned. Therefore, different design strategies (e.g., functional gradient) can be implemented to design advanced engineering materials with unusual properties. Here, using the theory of elasticity and finite element modeling, we propose a fast and direct approach to effectively design the microarchitectures of mechanical metamaterials with re-entrant structures that allow predicting complex deformation shapes under uniaxial tensile loading. We also analyze the efficiency of this method by back calculating the microarchitectural designs of mechanical metamaterials to predict the complex 1-D external contour of objects (e.g., vase and foot). The proposed approach has several applications in creating programmable mechanical metamaterials with shape matching properties for exoskeletal and soft robotic devices.
13
Irsyad, As’Ary Sahlul, Muhammad Ikhsan, and Aidil Halim Lubis. "USE OF PROPORTIONAL INTEGRAL DERIVATIVE (PID) ALGORITHM IN GRASS POISONING ROBOT." JURTEKSI (Jurnal Teknologi dan Sistem Informasi) 9, no. 3 (June 7, 2023): 377–84. http://dx.doi.org/10.33330/jurteksi.v9i3.2210.
Abstract:
Abstract: Grass is one of the plants that live on God's earth, even grass is also written in Al-quran. Grass is currently also a pest for plants, so sometimes to minimize grass growth, many farmers or people eradicate grass by cutting it even by poisoning the grass. Each method used has its own risk of work accidents, such as using grass poison can experience insecticide poisoning. To anticipate this, a remotecontrol robot that sprays automatic grass poison using the PID method is designed. The test results found that the robot works with a voltage of 11.1 VDC with a 5-12VDC motor with a speed of 3000rpm and a gearbox motor is used so that it turns into a 5Kg load torque. Meanwhile, for control using the HC-05 interface which is connected to Android, the maximum distance transmission system is 0-10m. For watering grass, it has 2 scala heights, grass with a height of 10-15 uses PID 1, which is watered with a voltage of 11.1VDC delay (t) 1.5s. Grass with a height of 25-30 using PID 2, watered with a voltage of 14.8VDC delay (t) 3s. All watering the grass uses a 16VDC pump motor with 1500 rpm. After the robotic watering system is applied using the PID method, the P value = 14.56. The value of I = 22.08 and the value of D = 15.5. Keywords : Control Remote; PID method; Poison sprinkler robot Abstrak: Rumput merupakan salah satu tumbuhan yang hidup dimuka bumi allah, bahkan rumput juga tertulis didalam Al-quran. Rumput saat ini juga sebagai hama bagi tumbuhan, sehingga terkadang untuk meminimalisir pertumbuhan rumput, banyak petani atau orang yang membasmi rumput dengan cara dipotong bahkan sampai dengan cara meracun rumput tersebut. Setiap cara yang digunakan memiliki resiko kecelakaan kerja tersendiri, seperti menggunakan racun rumput bisa mengalami Keracunan insektisida. Untuk mengantisipasi hal tersebut, maka dirancang robot kendali distance jauh penyiram racun rumput otomatis menggunakan metode PID. Hasil pengujian mendapati robot bekerja dengan tegangan 11.1 VDC dengan motor penggerak 5-12VDC dengan kecepatan 3000rpm dan dipakaikan motor gearbox sehingga berubah kedalam bentuk torsi beban 5Kg. Sementara untuk kendali menggunakan interface HC-05 yang terhubung ke Android, sistem pengiriman distance maksimal 0-10m. Untuk penyiraman rumput, memiliki 2 scala tinggi, rumput dengan tinggi 10-15 menggunakan PID 1, yaitu disiram dengan tegangan 11.1VDC delay (t) 1.5s. Rumput dengan tinggi 20-30 menggunakan PID 2, disiram dengan tegangan 14.8VDC delay (t) 3s. Seluruh penyiraman rumputmenggunakan motor pompa 16VDC dengan rpm 1500. Setelah sistem penyiraman robot diterapkan dengan metode PID, maka nilai P = 14,56. Nilai I = 22,08 dan nilai D = 15.5. Kata kunci: Kendali Jarak Jauh; Metode PID; Robot penyiram racun
14
Qu, Y. F., J. H. Ma, Y. Q. He, L. Zhang, F. C. Ren, and B. Li. "3D printing-directed flexible strain sensors of accordion-like architecture to achieve ultrastretchability with the assist of ultrasonic cavitation treatment." Journal of Physics: Conference Series 2085, no. 1 (November 1, 2021): 012042. http://dx.doi.org/10.1088/1742-6596/2085/1/012042.
Abstract:
Abstract A new class of accordion-like cellular architecture with sinusoidal struts is designed to enhance the planar stretchability of cellular solids, aiming to fabricate flexible strain sensors with ultrastretchability. The combination manufacturing process of fused deposition modeling (FDM) 3D printing technique and ultrasonic cavitation-enabled treatment was introduced into the fabrication of flexible strain sensors made of thermoplastic polyurethane (TPU) substrate and carbon nanotubes (CNTs). A negative Poisson’s ratio (NPR) architecture made of TPU was firstly 3D-printed by FDM. The ultrasonic cavitation treatment was then conducted on the soft auxetic structure immersing in CNTs liquid, aiming to embed the CNTs into the surface layer of the flexible TPU substrate with NPR configurations. Instead of 3D printing the TPU matrix composite after hybridization inside the matrix material, the hybrid manufacturing procedure can ensure that the intrinsic excellent mechanical properties of TPU are not embrittled. Besides, the sinusoidal struts in accordion-like cellular architectures offer a design route to extend the material property chart to achieve ultrahigh stretchability in lightweight 3D printable flexible polymers for the applications that require combined stretchability, lightweight, and energy absorption such as soft robotics, stretchable electronics, and wearable protection shields.
15
Hosseinian, S., and H. Arefi. "ASSESSMENT OF RESTORATION METHODS OF X-RAY IMAGES WITH EMPHASIS ON MEDICAL PHOTOGRAMMETRIC USAGE." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B5 (June 16, 2016): 835–40. http://dx.doi.org/10.5194/isprs-archives-xli-b5-835-2016.
Abstract:
Nowadays, various medical X-ray imaging methods such as digital radiography, computed tomography and fluoroscopy are used as important tools in diagnostic and operative processes especially in the computer and robotic assisted surgeries. The procedures of extracting information from these images require appropriate deblurring and denoising processes on the pre- and intra-operative images in order to obtain more accurate information. This issue becomes more considerable when the X-ray images are planned to be employed in the photogrammetric processes for 3D reconstruction from multi-view X-ray images since, accurate data should be extracted from images for 3D modelling and the quality of X-ray images affects directly on the results of the algorithms. For restoration of X-ray images, it is essential to consider the nature and characteristics of these kinds of images. X-ray images exhibit severe quantum noise due to limited X-ray photons involved. The assumptions of Gaussian modelling are not appropriate for photon-limited images such as X-ray images, because of the nature of signal-dependant quantum noise. These images are generally modelled by Poisson distribution which is the most common model for low-intensity imaging. In this paper, existing methods are evaluated. For this purpose, after demonstrating the properties of medical X-ray images, the more efficient and recommended methods for restoration of X-ray images would be described and assessed. After explaining these approaches, they are implemented on samples from different kinds of X-ray images. By considering the results, it is concluded that using PURE-LET, provides more effective and efficient denoising than other examined methods in this research.
16
Tipaldi, Gian Diego, and Kai Arras. "Planning Problems for Social Robots." Proceedings of the International Conference on Automated Planning and Scheduling 21 (March 22, 2011): 339–42. http://dx.doi.org/10.1609/icaps.v21i1.13481.
Abstract:
As robots enter environments that they share with people, human-aware planning and interaction become key tasks to be addressed. For doing so, robots need to reason about the places and times when and where humans are engaged into which activity and plan their actions accordingly. In this paper, we first address this issue by learning a nonhomogenous spatial Poisson process whose rate function encodes the occurrence probability of human activities in space and time. We then present two planning problems for human robot interaction in social environments. The first one is the maximum encounter probability planning problem, where a robot aims to find the path along which the probability of encountering a person is maximized. We are interested in two versions of this problem, with deadlines or with a certainty quota. The second one is the minimum interference coverage problem, where a robot performs a coverage task in a socially compatible way by reducing the hindrance or annoyance caused to people. An example is a noisy vacuum robot that has to cover the whole apartment having learned that at lunch time the kitchen is a bad place to clean. Formally, the problems are time dependent variants of known planning problems: MDPs and price collecting TSP for the first problem and the asymmetric TSP for the second. The challenge is that the cost functions of the arcs and nodes vary with time, and that execution time is more important that optimality, given the real-time constraints in robotic systems. We present experimental results using variants of known planners and formulate the problems as benchmarks to the community.
17
Hosseinian, S., and H. Arefi. "ASSESSMENT OF RESTORATION METHODS OF X-RAY IMAGES WITH EMPHASIS ON MEDICAL PHOTOGRAMMETRIC USAGE." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B5 (June 16, 2016): 835–40. http://dx.doi.org/10.5194/isprsarchives-xli-b5-835-2016.
Abstract:
Nowadays, various medical X-ray imaging methods such as digital radiography, computed tomography and fluoroscopy are used as important tools in diagnostic and operative processes especially in the computer and robotic assisted surgeries. The procedures of extracting information from these images require appropriate deblurring and denoising processes on the pre- and intra-operative images in order to obtain more accurate information. This issue becomes more considerable when the X-ray images are planned to be employed in the photogrammetric processes for 3D reconstruction from multi-view X-ray images since, accurate data should be extracted from images for 3D modelling and the quality of X-ray images affects directly on the results of the algorithms. For restoration of X-ray images, it is essential to consider the nature and characteristics of these kinds of images. X-ray images exhibit severe quantum noise due to limited X-ray photons involved. The assumptions of Gaussian modelling are not appropriate for photon-limited images such as X-ray images, because of the nature of signal-dependant quantum noise. These images are generally modelled by Poisson distribution which is the most common model for low-intensity imaging. In this paper, existing methods are evaluated. For this purpose, after demonstrating the properties of medical X-ray images, the more efficient and recommended methods for restoration of X-ray images would be described and assessed. After explaining these approaches, they are implemented on samples from different kinds of X-ray images. By considering the results, it is concluded that using PURE-LET, provides more effective and efficient denoising than other examined methods in this research.
18
Zhang, Z., and A. O. Krushynska. "Programmable shape-morphing of rose-shaped mechanical metamaterials." APL Materials 10, no. 8 (August 1, 2022): 080701. http://dx.doi.org/10.1063/5.0099323.
Abstract:
Shape morphing is one of the most attractive functionalities of materials that are desired in many applications, including robotic grippers, medical stents, wearable electronics, and so on. Shape morphing can be implemented by using mechanical metamaterials that combine building blocks with properly designed mechanical or material properties. The design approaches are, however, mostly ad hoc or require materials with special properties. This work proposes two automated design strategies for programmable shape morphing and validates them on structures 3D-printed from a widely available commercial Stereolithography Durable resin. We proposed a so-called rose-shaped metamaterial with reduced stress concentration due to the absence of sharp corners and with a large range of tailorable Poisson’s ratios, from −0.5 to 0.9, governed by a single design parameter. We programmed the shape of the rose-shaped metamaterial sheets aiming at high shape comfortability or uniform effective stiffness. The shape-morphing performance is demonstrated in the linear (0.1% strain) and non-linear (20% strain) deformation regimes, and it agrees well with the tensile test results. Our findings show the potential to develop complex practical metamaterial structures at comparatively low costs.
19
Lee, Ju-Yong, Min-Ha Oh, Joo-Hyeon Park, Se-Hun Kang, and Seung-Kyun Kang. "Three-Dimensionally Printed Expandable Structural Electronics Via Multi-Material Printing Room-Temperature-Vulcanizing (RTV) Silicone/Silver Flake Composite and RTV." Polymers 15, no. 9 (April 23, 2023): 2003. http://dx.doi.org/10.3390/polym15092003.
Abstract:
Three-dimensional (3D) printing has various applications in many fields, such as soft electronics, robotic systems, biomedical implants, and the recycling of thermoplastic composite materials. Three-dimensional printing, which was only previously available for prototyping, is currently evolving into a technology that can be utilized by integrating various materials into customized structures in a single step. Owing to the aforementioned advantages, multi-functional 3D objects or multi-material-designed 3D patterns can be fabricated. In this study, we designed and fabricated 3D-printed expandable structural electronics in a substrateless auxetic pattern that can be adapted to multi-dimensional deformation. The printability and electrical conductivity of a stretchable conductor (Ag-RTV composite) were optimized by incorporating a lubricant. The Ag-RTV and RTV were printed in the form of conducting voxels and frame voxels through multi-nozzle printing and were arranged in a negative Poisson’s ratio pattern with a missing rib structure, to realize an expandable passive component. In addition, the expandable structural electronics were embedded in a soft actuator via one-step printing, confirming the possibility of fabricating stable interconnections in expanding deformation via a missing rib pattern.
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Pekkanen, Suvi, Satu Rautaoja, Risto Kauppinen, Leena Ahola, Jaakko Mononen, and Petri Kainulainen. "Lypsylehmät sopeutuivat hyvin siirtoon parsinavetasta automaattiseen lypsyjärjestelmään." Suomen Maataloustieteellisen Seuran Tiedote, no. 21 (January 31, 2006): 1–6. http://dx.doi.org/10.33354/smst.76771.
Abstract:
Tutkimuksessa tarkasteltiin lypsylehmien yksilöllistä sopeutumista siirryttäessä suoraan parsinavetastapihaton automaattiseen lypsyjärjestelmään. Tutkimus toteutettiin tapaustutkimuksena lämminpihatossakevään ja syksyn 2004 välisenä aikana sekä kyselytutkimuksena 16 tilalle, jotka olivat siirtyneetsuoraan parsinavetasta automaattiseen lypsyjärjestelmään. Suurin osa lehmistä tottui nopeasti uuteenlypsyjärjestelmään. Lehmien totuttamiseen tarvittiin jonkun verran ylimääräistä työtä kahdenensimmäisen viikon aikana siirron jälkeen. Työ oli lähinnä lehmien ajamista robotille.TapaustutkimusTapaustutkimuksessa 28 ayshire lehmää siirrettiin suoraan parsinavetasta pihattoon ja robottilypsyyn.Pihattoon siirrettyjen lehmien annettiin ensin tutustua rauhassa uuteen ympäristöön. Totutettaessalehmiä robotille houkutusrehua oli jatkuvasti tarjolla. Tarvittaessa lehmiä ajettiin, vedettiin jatyönnettiin robotille. Lehmien käyttäytymistä tarkkailtiin suoralla seurannalla (focal sampling) niidenmennessä robotille kahdeksalla lypsykerralla neljän päivän ajan. Pelkkiä robotin läpikulkukertoja eihuomioitu laskennassa.Kaksikymmentä lehmää käyttäytyi rauhallisesti ja pelottomasti heti ensimmäisestä robotillakäyntikerrasta lähtien. Kuudennella lypsykerralla kirjattiin havainnot 18 lehmästä, joista yhtä vaillekaikki kulkivat robotille joko aivan itsenäisesti tai vaativat vain vähäistä ajamista. Kaksi viikkoarobotin käyttöönoton jälkeen kaikki lehmät kävivät robotilla ilman ajamistaKyselytutkimusKyselytutkimus tehtiin 16 tilalle, jotka olivat siirtyneet suoraan parsinavetasta automaattiseenlypsyjärjestelmään. Kyselytutkimus tuki tapaustutkimuksen havaintoja. Vastausten mukaan lehmätsuhtautuivat lypsyrobottiin uteliaasti. Parsinavetasta automaattiseen lypsyjärjestelmään siirryttäessä80 % lehmistä tottui uuteen järjestelmään helposti.Lehmiä oli totutettu lypsyrobottiin ajamalla (11 tilaa), rehulla houkuttelemalla (7), vetämällä (3)ja jollakin muulla tavalla (5). Muita tapoja olivat lehmän työntäminen lypsyrobottiin sekä lehmienvieminen navettaan ennen lypsyrobotin käyttöönottoa. Yhdellä tilalla lehmiä totutettiin pyyhkimälläniiden utareita lypsypyyhkeellä ennen robottilypsyä, jotta lehmällä olisi lypsytapahtumassa jotaintuttua. Useilla tiloilla käytettiin useita totutustapoja yhtäaikaisesti, jotta tottuminen nopeutuisi.Ensikoiden ja vanhempien lehmien tottumisessa robottiin ei ollut vastausten mukaan suuria eroja. Yksitai useampi lehmä poistettiin joka toisella tilalla automaattiseen lypsyjärjestelmään siirryttäessä.Yleisin poiston syy oli matala, robottiin sopimaton utarerakenne.
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Zhang, Jiachen, Ziyu Ren, Wenqi Hu, Ren Hao Soon, Immihan Ceren Yasa, Zemin Liu, and Metin Sitti. "Voxelated three-dimensional miniature magnetic soft machines via multimaterial heterogeneous assembly." Science Robotics 6, no. 53 (April 28, 2021): eabf0112. http://dx.doi.org/10.1126/scirobotics.abf0112.
Abstract:
Small-scale soft-bodied machines that respond to externally applied magnetic field have attracted wide research interest because of their unique capabilities and promising potential in a variety of fields, especially for biomedical applications. When the size of such machines approach the sub-millimeter scale, their designs and functionalities are severely constrained by the available fabrication methods, which only work with limited materials, geometries, and magnetization profiles. To free such constraints, here, we propose a bottom-up assembly-based 3D microfabrication approach to create complex 3D miniature wireless magnetic soft machines at the milli- and sub-millimeter scale with arbitrary multimaterial compositions, arbitrary 3D geometries, and arbitrary programmable 3D magnetization profiles at high spatial resolution. This approach helps us concurrently realize diverse characteristics on the machines, including programmable shape morphing, negative Poisson’s ratio, complex stiffness distribution, directional joint bending, and remagnetization for shape reconfiguration. It enlarges the design space and enables biomedical device-related functionalities that are previously difficult to achieve, including peristaltic pumping of biological fluids and transport of solid objects, active targeted cargo transport and delivery, liquid biopsy, and reversible surface anchoring in tortuous tubular environments withstanding fluid flows, all at the sub-millimeter scale. This work improves the achievable complexity of 3D magnetic soft machines and boosts their future capabilities for applications in robotics and biomedical engineering.
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Saravana Jothi, N. S., and A. Hunt. "Active mechanical metamaterial with embedded piezoelectric actuation." APL Materials 10, no. 9 (September 1, 2022): 091117. http://dx.doi.org/10.1063/5.0101420.
Abstract:
Metamaterials are artificially structured materials and exhibit properties that are uncommon or non-existent in nature. Mechanical metamaterials show exotic mechanical properties, such as negative stiffness, vanishing shear modulus, or negative Poisson’s ratio. These properties stem from the geometry and arrangement of the metamaterial unit elements and, therefore, cannot be altered after fabrication. Active mechanical metamaterials aim to overcome this limitation by embedding actuation into the metamaterial unit elements to alter the material properties or mechanical state. This could pave the way for a variety of applications in industries, such as aerospace, robotics, and high-tech engineering. This work proposes and studies an active mechanical metamaterial concept that can actively control the force and deformation distribution within its lattice. Individually controllable actuation units are designed based on piezostack actuators and compliant mechanisms and interconnected into an active metamaterial lattice. Both the actuation units and the metamaterial lattice are modeled, built, and experimentally studied. In experiments, the actuation units attained 240 and 1510 µm extensions, respectively, in quasi-static and resonant operation at 81 Hz, and 0.3 N blocked force at frequencies up to 100 Hz. Quasi-static experiments on the active metamaterial lattice prototype demonstrated morphing into four different configurations: Tilt left, tilt right, convex, and concave profiles. This demonstrated the feasibility of altering the force and deformation distribution within the mechanical metamaterial lattice. Much more research is expected to follow in this field since the actively tuneable mechanical state and properties can enable qualitatively new engineering solutions.
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Turner, Joel G., Thomas C. Rowe, David A. Ostrov, Elizabeth J. Ciaravino, Jana L. Gump, and Daniel M. Sullivan. "Blocking a Topoisomerase IIα Nuclear Export Signal Sensitizes Human Multiple Myeloma Cells to Topoisomerase II Inhibitors." Blood 114, no. 22 (November 20, 2009): 2850. http://dx.doi.org/10.1182/blood.v114.22.2850.2850.
Abstract:
Abstract Abstract 2850 Poster Board II-826 Background We have previously demonstrated that topoisomerase IIa (topo IIa) is exported from the nucleus of high density human multiple myeloma (MM) cells by a CRM1-dependent mechanism (Engel et al, Exp. Cell Res. 295(2):421-31, 2004). We have also identified the nuclear export signals (NES) for topo IIa at amino acids 1017-28 (site 1) and 1054-66 (site 2) using mutated full-length FLAG-tagged topo IIa protein and immunofluorescence microscopy (Turner et al, J. Cell Sci. 117:3061-71, 2004). Drug resistance to topo II poisons occurs when topo II is trafficked to the cytoplasm where it is not in contact with the DNA and thus unable to induce cell death in response to topo II inhibitors. In addition, we have recently shown that blocking nuclear export of topo IIα with a CRM1 inhibitor or by siRNA sensitizes MM cells to topo II poisons (Turner et al, Cancer Res. In press). Materials and Methods The structure of S. cerevisiae topo II was used to create a model of human topo IIα using the program Protein Homology/analogy Recognition Engine (Phyre), available on the Web (http://www.imperial.ac.uk/phyre). The procedure for molecular docking involved selection of structural pockets of the NES in topo IIa that were suitable for interactions with drug-like small molecule inhibitors (SMI). Molecular docking simulations screened 140,000 small molecules (mw < 500) from the NCI database. The top scoring SMI for each of the two NES (20 total) were obtained from NCI and tested for induction of apoptosis (caspase 3) and anti-proliferative activity using CellTiter-Blue (Promega). Cell types used included human MM RPMI 8226 and NCI-H929 cells. SMI were tested both as single agents and in combination experiments with the topo II inhibitor doxorubicin. In addition, immunofluorescence microscopy for the intracellular location of topo IIα in SMI-treated MM cells was also performed. Results Low density myeloma cells: Robotic cell viability assays determined that several of the SMI had anti-proliferative activity. However, only SMI that docked to NES site 1 showed any inhibition of viability. The IC50 values obtained from single-drug cell viability assays in low density cells revealed two SMI compounds with IC50 values of 4.7 and 11.1 μM. None of the SMI affected the viability of high density cells (IC50 >100 μM). High density drug-resistant myeloma cells: Data from apoptosis assays indicated that four of the SMI that docked to NES site 1 significantly (p<0.05) sensitized high density MM cells to doxorubicin. Immunofluorescence microscopy revealed an increase in topo IIα in the cell nucleus of cells treated for 20 hours with the four lead SMI. Conclusions Using computer-generated molecular modeling, we have identified four lead compounds from the NCI database that bind to the site 1 NES of topo IIα. These lead compounds are SMI that synergize with the topo II inhibitor doxorubicin. In vitro apoptosis assays indicate that these drugs may be effective as single agents or in combination with currently used cancer drugs that target topo II. These data may have potential clinical implications in the treatment of multiple myeloma. Disclosures: Sullivan: Merck: Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; Merrion: Membership on an entity's Board of Directors or advisory committees.
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Turner, Joel G., Thomas C. Rowe, David Ostrov, Jana L. Dawson, Elizabeth Ciaravino, and Daniel Sullivan. "Novel Drug Targets to Overcome De Novo Drug-Resistance In Multiple Myeloma." Blood 116, no. 21 (November 19, 2010): 3006. http://dx.doi.org/10.1182/blood.v116.21.3006.3006.
Abstract:
Abstract Abstract 3006 Abstract Human multiple myeloma (MM) still remains an incurable disease despite improved treatment regimens that include bortezomib, lenalidomide and thalidomide. New therapeutic targets are needed to further improve treatment outcomes. We have shown that targeting intracellular trafficking of proteins may sensitize cells to antitumor agents (Turner et al. 2009, Cancer Res, 69, 6899-905). We have previously demonstrated that topoisomerase II alpha (topo IIα) trafficking from the nucleus to the cytoplasm in myeloma cells occurs by a CRM1-dependent mechanism and resulting in drug resistance to topo II inhibitors (Engel et al. 2004, Exp Cell Res, 295, 421-31). We have also identified the nuclear export signals (NES) for topo IIα at amino acids 1017-28 (site 1) and 1054-66 (site 2) (Turner et al. 2004, J Cell Sci, 117, 3061-71). Blocking nuclear export of topo IIα with a CRM1 inhibitor or by siRNA has been shown to sensitize MM cells to topo II poisons (Turner et al. 2009, Cancer Res, 69, 6899-905). The NES amino acid sequence of topo IIα at 1017–1028 is a unique site. Even though this site conforms to the hydrophobic amino acid motif for an NES, the amino acid sequence does not occur in any other human protein. In addition, this NES is in a pocket formed by the three-dimensional structure of the topo IIα protein. These factors allow the potential for the development of drugs that will exclusively block the NES of topo IIα and not affect the export of other nuclear proteins, as occurs with other known CRM1 inhibitors. Drug resistance to topo II inhibitors occurs when topo IIα is trafficked from the nucleus to the cytoplasm where it is no longer in contact with the DNA, and thus unable to induce cell death (Valkov et al 2000, Br J Haematol, 108, 331-45, Engel et al. 2004, Exp Cell Res, 295, 421-31). We therefore hypothesize that targeting a specific NES in topo IIα is an innovative treatment approach in MM and may allow a very focused and potent combination with topo II inhibitors, possibly overcoming de novo drug resistance in this malignancy. To date, we know of no agents that target the NES of a specific protein that are being developed to treat cancer. A computer generated hybrid molecule using the known three dimensional structure of yeast topo II and the human NES sequences of topo IIα was produced. Molecules were docked in silico using the NCI small molecule database (140,000 compounds). The molecules with the highest docking scores were obtained from NCI and assayed for IC50 values and synergy with the topo II inhibitor doxorubicin. All NES site 1 molecules tested showed activity, however, none of the NES site 2 molecules exhibited any anti-neoplastic activity with or without a topo II inhibitor. CT blue (Promega) robotic cell viability assays determined that several of the site 1 inhibitors had anti-proliferative activity. The IC50 values obtained from single drug cell viability assays in low density cells revealed two site 1 inhibitors compounds with IC50 values of 4.7 (NCI-36400) and 11.1 μM (NCI-35847). None of the site 1 inhibitors affected the viability of high-density cells (IC50>100 μM). Data from apoptosis assays indicate that three of the site 1 inhibitors (NCI-36400, NCI-35847, NCI-35024) that dock to NES site 1 do significantly (p<0.05) sensitize high density MM cells to doxorubicin. Immunofluorescence microscopy revealed an increase in topo IIα in the cell nucleus of cells treated for 20 hours with the three lead site 1 inhibitors. Nuclear-cytoplasmic fractionation revealed that the NES site 1 docking molecules prevent nuclear export of topo IIα. These compounds may lead to new chemotherapeutic treatments of myeloma. Disclosures: No relevant conflicts of interest to declare.
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ERDOĞMUŞ, Alim Kerem, and Uğur YAYAN. "Verification and Validation of Camera Based Robotic Inspection System via Camera Fault Injection Tool." Eskişehir Osmangazi Üniversitesi Mühendislik ve Mimarlık Fakültesi Dergisi, February 20, 2024. http://dx.doi.org/10.31796/ogummf.1348531.
Abstract:
Günümüzde, gelişen görüntü işleme teknikleri ile birlikte kamera tabanlı robotik inceleme sistemleri oldukça popülerlik kazanmıştır. Bu tür sistemler gıdadan, askeriyeye birçok sektörde yoğun olarak kullanılmaktadır. Bu sistemler geliştirilirken gerekli olan doğrulama ve onaylama süreçleri oldukça uzun ve maliyetli olmaktadır. Bu çalışma, kamera tabanlı endüstriyel robotik sistemler üzerinde doğrulama ve onaylama faaliyetlerini gerçekleştirmek ve iyileştirmek amacıyla geliştirilmiştir. RGB ve TOF kameralara farklı türlerde (Open, Close, Dilation, Erosion, Gradient, Motionblur, Tuz&Biber, Gaussian ve Poisson) hata enjeksiyon yöntemleri kullanılmasını mümkün Kamera Hata Enjeksiyon Aracı (CamFITool) ile gerçekleştirilmiş testler ve sonuçlar açıklanmıştır. Yapılan çalışma, VALU3S projesi kapsamında, OTOKAR’ın ROKOS robotik sistemine, CamFITool ile gerçek ortamdan alınmış kamera görüntülerinden oluşan kitaplıklara, çeşitli konfigürasyonlarda hatalar enjekte edilip, bu enjeksiyonun sisteme etkilerinin incelenmesine odaklanmıştır. Bu kapsamda 49 farklı test komfigürasyonunda hata enjeksiyonu gerçekleştirilmiştir. Sonuç olarak, kamera tabanlı endüstriyel robotik sistemlerin daha güvenli ve stabil çalışmalarının sağlanması için, bu sistemlerin hataya dayanıklı olup olmadıklarını test eden açık kaynaklı bir hata enjeksiyon aracı olan CamFITool önerilmiştir.
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Li, Zixuan. "A Novel Squid-Inspired AUV Design: Revolutionizing Coral Reef Preservation Through CFD and Experimental Insights into Drag and Maneuverability." Science and Technology of Engineering, Chemistry and Environmental Protection 1, no. 3 (October 22, 2023). http://dx.doi.org/10.61173/5jgtw752.
Abstract:
This study focuses on conceptualizing and optimizing an advanced bionic robotic solution to surmount the limitations of current observational vehicles in coral reef conservation. Human divers are traditionally subjected to physiological challenges, while current robotic alternatives grapple with operational impediments, including anthropogenic marine disturbances. Utilizing advanced robotics tailored for marine ecosystems with intricate topologies and fragile corals, this study aims to enhance conservation precision in the face of climatic shifts and marine pollution from anthropogenic activities.This paper develops a squid-inspired Autonomous Underwater Vehicle (AUV), whose behavior is then examined and improved utilizing both experiments and Computational Fluid Dynamics.(CFD). The governing equations considered here are the incompressible Reynolds-Averaged Navier-Stokes (RANS) with an iterative solver for both the pressure-Poisson and momentum equations. Apart from CFD analysis, a prototype was assembled and experimentally tested to validate the CFD outcomes and assess the lift from its bionic rudders. The maneuverability is optimized through careful designs and parameter studies of several features.A head length is determined to balance viscous and pressure drag while achieving the least total drag in the AUV design. Additionally, a disk is introduced at the AUV’s front, which reduces fluid contact, thereby decreasing the viscous drag. While this modification slightly increased pressure drag, it yielded an overall reduction in total drag. Experimental observations confirmed a propulsion speed and underscored the necessity for maximizing rudder extension.The developed AUV’s squid-like design, optimized via CFD, ensures drag reduction by 5.34% and energy efficiency. By mimicking squid dynamics, disturbances to marine biota are minimized. The incorporation of bionic fins, empirically fine-tuned, enhances the AUV’s agility. These attributes establish it as an exceptional prototype, setting a precedent for future coral reef monitoring systems and augmenting conservation strategies.
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Huang, Xin, Tianzhao Bu, Qingyang Zheng, Shaoyu Liu, Yangyang Li, Han Fang, Yuqi Qiu, Bin Xie, Zhouping Yin, and Hao Wu. "Flexible sensors with zero Poisson's ratio." National Science Review, January 23, 2024. http://dx.doi.org/10.1093/nsr/nwae027.
Abstract:
Abstract Flexible sensors have been developed to provide sufficient perception capability for various stimuli. However, the complex deformation, usually results from forces or strains from multi-axes, can be challenging to measure due to the lack of independent perception of multi-axial stimuli. Herein, flexible sensors based on the metamaterial membrane with zero Poisson's ratio (ZPR) are proposed to achieve independent detection of biaxial stimuli. By deliberately designing the geometric dimensions and arrangement parameters of elements, the Poisson's ratio of elastomer membrane can be modulated from negative to positive, and the ZPR membrane can maintain a constant transverse dimension under longitudinal stimuli. Due to the accurate monitoring of grasping force by ZPR sensors that are insensitive to curvatures of contact surfaces, rigid robotic manipulators can be guided to safely grasp deformable objects. Meanwhile, the ZPR sensor can also precisely distinguish different states of manipulators. When ZPR sensors are attached to a thermal-actuation soft robot, they can accurately detect the moving distance and direction. This work presents a new strategy for independent biaxial stimuli perception through the design of mechanical metamaterials, which may inspire the future development of advanced flexible sensors for healthcare, human-machine interfaces and robotic tactile sensing.
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McCarthy, Elizabeth, Benjamin L. Gough, Michael S. Johns, Alexandra Hanlon, Sachin Vaid, and Nicholas Petrelli. "A Comparison of Colectomy Outcomes Utilizing Open, Laparoscopic, and Robotic Techniques." American Surgeon, December 19, 2020, 000313482097338. http://dx.doi.org/10.1177/0003134820973384.
Abstract:
Introduction Robotic colectomy could reduce morbidity and postoperative recovery over laparoscopic and open procedures. This comparative review evaluates colectomy outcomes based on surgical approach at a single community institution. Methods A retrospective review of all patients who underwent colectomy by a fellowship-trained colon and rectal surgeon at a single institution from 2015 through 2019 was performed, and a cohort developed for each approach (open, laparoscopic, and robotic). 30-day outcomes were evaluated. For dichotomous outcomes, univariate logistic regression models were used to quantify the individual effect of each predictor of interest on the odds of each outcome. Continuous outcomes received a similar approach; however, linear and Poisson regression modeling were used, as appropriate. Results 115 patients were evaluated: 14% (n = 16) open, 44% (n = 51) laparoscopic, and 42% (n = 48) robotic. Among the cohorts, there was no statistically significant difference in operative time, rate of reoperation, readmission, or major complications. Robotic colectomies resulted in the shortest length of stay (LOS) (Kruskal-Wallis P < .0001) and decreased estimated blood loss (EBL) (Kruskal-Wallis P = .0012). Median age was 63 years (interquartile range [IQR] 53-72). 54% (n = 62) were female. Median American Society of Anesthesiologists physical status classification was 3 (IQR 2-3). Median body mass index was 28.67 (IQR 25.03-33.47). A malignant diagnosis was noted on final pathology in 44% (n = 51). Conclusion Among the 3 approaches, there was no statistically significant difference in 30-day morbidity or mortality. There was a statistically significant decreased LOS and EBL for robotic colectomies.
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"Smooth Path Planning of Ackerman Chassis Robot based on Improved ant Colony Algorithm." International Journal of Circuits, Systems and Signal Processing 14 (July 20, 2020). http://dx.doi.org/10.46300/9106.2020.14.49.
Abstract:
In the domain of robotics and autonomous driving, the automatic path planning of vehicle collision-free motion is an essential task on the navigation level. It is found that the traditional path planning algorithm and the ployline path cannot fully meet the driving requirements of Ackerman chassis robot. In order to solve the autonomous navigation problem of Ackerman chassis mobile robot in structured environment, this paper presents a new improved algorithm. The method of configuration space can introduce the robot's own structural size parameters into the algorithm. Through convex polygon detection method, the local U-shaped area in the map is transformed into a closed area. The essence of these two strategies is to preprocess the map. The initial pheromone distribution is no longer globally uniform, but is distributed according to the terrain. The volatilization factor of pheromone is changed from static constant to dynamic one, which is combined with Poisson distribution law. This strategy makes the improved pheromone distribution law not only avoid the randomness and blindness in the initial stage of the algorithm, but also ensure the ant colony's exploration behavior and guiding role in the middle stage of the algorithm. Path smoothing is also a challenging task. This algorithm optimizes the path step by step by improving the evaluation function, removing redundant nodes and 2-turning algorithm. Thus, a collision free smooth path suitable for Ackerman robot is obtained. This paper combines a variety of algorithm improvement strategies, not only improving the performance of ant colony algorithm path exploration, but also planning a smooth curve path suitable rather than polyline for Ackerman mobile robot tracking. The algorithm is coded and simulated by MATLAB, and the feasibility and effectiveness of the algorithm are verified. This will provide an important basis for the subsequent algorithm migration and lay the foundation for the path tracking control of the Ackermann chassis robot.
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Pellegrini, Alessandro, Maria Emanuela Palmieri, Fulvio Lavecchia, Luigi Tricarico, and Luigi Maria Galantucci. "Auxetic behavior of 3D-printed structure made in acrylonitrile butadiene styrene and carbon fiber-reinforced polyamide." Progress in Additive Manufacturing, June 6, 2023. http://dx.doi.org/10.1007/s40964-023-00465-0.
Abstract:
AbstractParts with an auxetic structure, which exhibit negative Poisson’s ratio, can be associated with a novel class of smart materials. Such interesting property has been widely explored, over the time, for different applications, i.e., medical, automotive, robotic and aeronautic field. However, the research about the design and analysis of auxetic behavior is still on the way. In this paper, a 2D re-entrant honeycomb structure was realized using material extrusion additive manufacturing technology. Two different materials, acrylonitrile butadiene styrene and carbon fiber-reinforced polyamide were adopted. The technique of digital image correlation was implemented during the tensile test to evaluate over the time and in different areas of specimens the strain behavior of the auxetic structure for both investigated materials. The measured negative Poisson’s ratio confirmed the auxetic behavior of the designed structure. The comparison between the two investigated materials showed a different trend of negative Poisson’s ratio.
31
Singh, Gaurav, Ahsan Nawroj, and Aaron M. Dollar. "Mechanical Characterization of Compliant Cellular Robots. Part I: Passive Stiffness." Journal of Mechanisms and Robotics, May 18, 2022, 1–22. http://dx.doi.org/10.1115/1.4054615.
Abstract:
Abstract Modular Active Cell Robots (MACROs) are a design paradigm for modular robotic hardware that uses only two components, namely actuators and passive compliant joints. Under the MACRO approach, a large number of actuators and joints are connected to create mesh-like robotic structures that can be actuated to achieve large deformation and shape-change. In this two-part paper, we study the importance of different possible mesh topologies within the MACRO framework. Regular and semi-regular tilings of the plane are used as the candidate mesh topologies and simulated using Finite Element Analysis (FEA). In Part 1, we use FEA to evaluate their passive stiffness characteristics. Using a strain energy method, the homogenized material properties (Young’s modulus, shear modulus, and Poisson’s ratio) of the different mesh topologies are computed and compared. The results show that the stiffnesses increase with increasing nodal connectivity and that stretching-dominated topologies have higher stiffness compared to bending-dominated ones. We also investigate the role of relative actuator-node stiffness on the overall mesh characteristics. This analysis shows that the stiffness of stretching-dominated topologies scale directly with their cross-section area whereas bending-dominated ones don’t have such a direct relationship.
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Aarthy, B., and B. Srutha Keerthi. "Enhancement of various images using coefficients obtained from a class of Sakaguchi type functions." Scientific Reports 13, no. 1 (October 31, 2023). http://dx.doi.org/10.1038/s41598-023-45938-y.
Abstract:
AbstractDigital image processing has a wide range of uses, including robotics and automated inspection of industrial parts. Other uses include remote sensing using satellites and other spacecraft, image transmission and storage for business applications, medical processing, and Acoustic image processing. The process of highlighting particular intriguing features in a hidden image is known as image enhancement. We can accomplish this by altering the brightness, contrast, etc. The generated output is more suitable than the original image for some particular purposes. The proposed algorithm which is based on the convolution of coefficient bounds of a subclass $$p-\Upsilon {\mathcal {S}}^*(t,\delta ,\mu )$$ p - Υ S ∗ ( t , δ , μ ) obtained using Mittag-Leffler type Poisson Distribution is tested on three image data sets with different dimensions and image formats (PNG, JPEG, TIFF, etc.) and its PSNR, SSIM, MSE, RMSE, PCC and MAE values are observed to check the quality of the enhanced images.
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Kim, Chae-Hwan, Hyun-Young Kim, Jun-Ho Kim, and Jaehwan Kim. "3D Printing-based Soft Auxetic Structures using PDMS-Ecoflex Hybrid." Functional Composites and Structures, March 2, 2023. http://dx.doi.org/10.1088/2631-6331/acc0cf.
Abstract:
Abstract Auxetic structures with negative Poisson’s ratio have received much attention due to their attractive behavioral properties in next-generation metamaterials and robotic applications. However, until now, there has been a lack of research into using soft materials to reliably develop a largely-deformable auxetic structures. Here, we develop soft PDMS-Ecoflex auxetic structures using a 3D printing technique, leading to high fabrication reliability and repeatability. Water-soluble filaments are employed to design sacrificial mold structures that quickly dissolve in warm water. By measuring the mechanical properties and light transmittance of soft composite membranes with various mixing ratios of PDMS and Ecoflex, the intrinsic characteristics of the composite membranes are determined. The newly fabricated soft auxetic structures composed of PDMS and Ecoflex composites always exhibit negative Poisson’s ratio during stretching. The negative Poisson’s ratio of the structure is maximized when PDMS and Ecoflex have a 2:1 mixing ratio and nominal strain is less than 5 %. Advances in technology to reliably fabricate soft auxetic structures using 3D printers are believed to promote next-generation applications such as wearable sensors and energy-absorbing structures.
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Dong, Le, Chengru Jiang, Jinqiang Wang, and Dong Wang. "Design of Shape Reconfigurable, Highly Stretchable Honeycomb Lattice With Tunable Poisson’s Ratio." Frontiers in Materials 8 (May 31, 2021). http://dx.doi.org/10.3389/fmats.2021.660325.
Abstract:
The mechanical behaviors of lattice structures can be tuned by arranging or adjusting their geometric parameters. Once fabricated, the lattice’s mechanical behavior is generally fixed and cannot adapt to environmental change. In this paper, we developed a shape reconfigurable, highly stretchable lattice structure with tunable Poisson’s ratio. The lattice is built based on a hexagonal honeycomb structure. By replacing the straight beam with curled microstructure, the stretchability of the lattice is significantly improved. The Poisson’s ratio is adjusted using a geometric angle. The lattice is 3D printed using a shape memory polymer. Using its shape memory effect, the lattice demonstrates tunable shape reconfigurability as the ambient temperature changes. To capture its high stretchability, tunable Poisson’s ratio and shape reconfigurability, a phase evolution model for lattice structure is used. In the theoretical model, the effects of temperature on the material’s nonlinearity and geometric nonlinearity due to the lattice structure are assumed to be decoupled. The theoretical shape change agrees well with the Finite element results, while the theoretical model significantly reduces the computational cost. Numerical results show that the geometrical parameters and the ambient temperature can be manipulated to transform the lattice into target shapes with varying Poisson’s ratios. This work provides a design method for the 3D printed lattice structures and has potential applications in flexible electronics, soft robotics, and biomedicine.
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Yang, Nan, Juncheng Zhuang, Shichuan Wei, and Ying Yu. "Continuous and Discrete Deformation Modes of Mechanical Metamaterials With Ring-Like Unit Cells." Frontiers in Physics 10 (July 4, 2022). http://dx.doi.org/10.3389/fphy.2022.909536.
Abstract:
Structures with multiple deformation paths provide a promising platform for robotics and reprogrammable mechanical and thermal deformation materials. Reconfigurations with a multi-path can fulfill many tasks (e.g., walking and grasping) and possess multiple properties (e.g., targeted Poisson’s ratio and thermal expansion coefficient). Here, we proposed a new ring-like kirigami structure and theoretically and experimentally found that for a basic unit, there are four discrete deformation patterns and a continuous shearing deformation pattern; thus, there are a large number of discrete deformation patterns for a multi-unit combination with geometrical compatibility coupled with a shearing deformation mode. Moreover, targeted Poisson’s ratios (either + or -) in the x- and y-directions can be realized by inversely designing the geometrical parameters for a certain deformation path. Additionally, we showed the capability of constructing 2D and 3D cellular structures in various patterns with the proposed ring-like units. The multiple deformation modes demonstrated here open up avenues to design new reprogrammable materials and robots across various scales.
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Liu, Kevin T., and G. H. Paulino. "Geometric mechanics of hybrid origami assemblies combining developable and non-developable patterns." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 480, no. 2282 (January 2024). http://dx.doi.org/10.1098/rspa.2023.0716.
Abstract:
Origami provides a method to transform a flat surface into complex three-dimensional geometries, which has applications in deployable structures, meta-materials, robotics and beyond. The Miura-ori and the eggbox are two fundamental planar origami patterns. Both patterns have been studied closely, and have become the basis for many engineering applications and derivative origami patterns. Here, we study the hybrid structure formed by combining unit cells of the Miura-ori and eggbox patterns. We find the compatibility constraints required to form the hybrid structure and derive properties of its kinematics such as self-locking and Poisson’s ratio. We then compare the aforementioned properties of the Miura-eggbox hybrid with those of the morph pattern, another generalization of the Miura-ori and eggbox patterns. In addition, we study the structure formed by combining all three unit cells of the Miura-ori, eggbox and morph. Our results show that such patterns have tunable self-locking states and Poisson’s ratio beyond their constituent components. Hybrid patterns formed by combining different origami patterns are an avenue to derive more functionality from simple constituents for engineering applications.
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Uddin, Kazi Zahir, Ibnaj Anamika Anni, George Youssef, and Behrad Koohbor. "Modulating poisson’s ratio in flexible honeycombs by density and architecture gradations." Engineering Research Express, September 26, 2023. http://dx.doi.org/10.1088/2631-8695/acfd81.
Abstract:
Abstract Zero Poisson’s ratio structures are a new class of mechanical metamaterials wherein the absence of lateral deformations allows the structure to adapt and conform their geometries to desired shapes with minimal interventions. These structures have gained attention in large deformation applications where shape control is a key performance attribute, with examples including but not limited to shape morphing, soft robotics, and flexible electronics. The present study introduces an experimentally driven approach that leads to the design and development of (near) zero Poisson’s ratio structures with considerable load-bearing capacities through concurrent density and architecture gradations in hybrid honeycombs created from hexagonal and re-entrant cells. The strain-dependent Poisson’s ratios in hexagonal and re-entrant honeycombs with various cell wall thicknesses have been characterized experimentally. A mathematical approach is then proposed and utilized to create hybrid structures wherein the spatial distribution of different cell shapes and densities leads to the development of honeycombs with minimal lateral deformations under compressive strains as high as 0.7. Although not considered design criteria, the load-bearing and energy absorption capacities of the hybrid structures are shown to be comparable with those of uniform cell counterparts. Finally, the new hybrid structures indicate lesser degrees of instability (in the form of cell buckling and collapse) due to the self-constraining effects imposed internally by the adjacent cell rows in the structures.
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Kim, Dong, Arman Safdari, and Kyung Chun Kim. "Sound pressure level spectrum analysis by combination of 4D PTV and ANFIS method around automotive side-view mirror models." Scientific Reports 11, no. 1 (May 27, 2021). http://dx.doi.org/10.1038/s41598-021-90734-1.
Abstract:
AbstractThis paper proposes a data augmentation method based on artificial intelligence (AI) to obtain sound level spectrum as predicting the spatial and temporal data of time-resolved three-dimensional Particle Tracking Velocimetry (4D PTV) data. A 4D PTV has used to measure flow characteristics of three side mirror models adopting the Shake-The-Box (STB) algorithm with four high-speed cameras on a robotic arm for measuring industrial scale. Helium filled soap bubbles are used as tracers in the wind tunnel experiment to characterize flow structures around automobile side mirror models. Full volumetric velocity fields and evolution of vortex structures are obtained and analyzed. Instantaneous pressure fields are deduced by solving a Poisson equation based on the 4D PTV data. To predict spatial and temporal data of velocity field, artificial intelligence (AI)-based data prediction method has applied. Adaptive Neural Fuzzy Inference System (ANFIS) based machine learning algorithm works well to find 4D missing data behind the automobile side mirror model. Using the ANFIS model, power spectrum of velocity fluctuations and sound level spectrum of pressure fluctuations are successfully obtained to assess flow and noise characteristics of three different side mirror models.
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Zhuang, Lei, De Lu, Jijun Zhang, Pengfei Guo, Lei Su, Yuanbin Qin, Peng Zhang, et al. "Highly cross-linked carbon tube aerogels with enhanced elasticity and fatigue resistance." Nature Communications 14, no. 1 (June 1, 2023). http://dx.doi.org/10.1038/s41467-023-38664-6.
Abstract:
AbstractCarbon aerogels are elastic, mechanically robust and fatigue resistant and are known for their promising applications in the fields of soft robotics, pressure sensors etc. However, these aerogels are generally fragile and/or easily deformable, which limits their applications. Here, we report a synthesis strategy for fabricating highly compressible and fatigue-resistant aerogels by assembling interconnected carbon tubes. The carbon tube aerogels demonstrate near-zero Poisson’s ratio, exhibit a maximum strength over 20 MPa and a completely recoverable strain up to 99%. They show high fatigue resistance (less than 1.5% permanent degradation after 1000 cycles at 99% strain) and are thermally stable up to 2500 °C in an Ar atmosphere. Additionally, they possess tunable conductivity and electromagnetic shielding. The combined mechanical and multi-functional properties offer an attractive material for the use in harsh environments.
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Park, Yeong Jae, Hyunje Ahn, and Hugo Rodrigue. "Shape‐Memory Alloy‐Based Auxetic Smart Metamaterials: Enabling Inherently Bidirectional Actuation." Advanced Intelligent Systems, March 21, 2024. http://dx.doi.org/10.1002/aisy.202400040.
Abstract:
Auxetic metamaterials, characterized by their negative Poisson's ratio, have garnered significant interest in various fields due to their unique mechanical properties. This article presents a pioneering approach to the development of auxetic smart metamaterials using shape memory alloy (SMA) as the core material. As SMAs can be Joule heated to change between their low‐ and high‐temperature phases to trigger the actuation of the structure, the auxetic smart metamaterial can actively modify its shape and stiffness to produce bidirectional actuation with a single power input and using a single bias mechanical element. The proposed active auxetic metamaterial consists of an SMA plate patterned with auxetic cuts, creating hinges that modulate the deformation of the structure to produce an auxetic behavior. This work looks at the impact of different geometric parameters on the behavior of the structure, including its generated force, its maximum strain, and its Poisson's ratio. The study also investigates the effect of the number of segmented units, revealing that designs with more segmented units suffer from stress concentrations near attachment points, limiting their advantages. This article shows that smart materials can help imbue metamaterials such as auxetic metamaterials with active properties to facilitate their implementation in future robotic applications.
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Ramírez-Gutiérrez, Diana L., Enrique Cuan-Urquizo, and Rita Q. Fuentes-Aguilar. "Sine-based lattice plates: additive manufacturing and their mechanical properties when loaded out of plane." Rapid Prototyping Journal, May 29, 2023. http://dx.doi.org/10.1108/rpj-01-2023-0010.
Abstract:
Purpose Demanding applications could benefit from the mathematical parametrization of lattice structures as this could lead not only to the characterization of structure–property relation but also facilitates the tailoring of the effective mechanical properties. This paper aims to characterize the mechanical performance of sine-based lattices. The characterization includes the results of in-plane Poisson’s ratio plates models, and the stiffness of additively manufactured lattice plates when loaded in the out-of-plane direction, with the objective of obtaining a relation with their geometrical parameters. Design/methodology/approach The geometrical parameter–Poisson’s ratio relationship was characterized via finite element (FE) simulations. The stiffness was also measured on additively manufactured polylactic acid lattice plates and contrasted with FE computations. Findings The characterization of auxetic lattice plates performed using in-plane and out-of-plane loading leads to key properties when deciding the geometry specific for applications: relative density, auxetic behavior and stiffness. Approximately 26% reduction of stiffness was observed between the square lattice and sine-based lattices of the same volume fraction. Originality/value Auxetic metamaterials are potential candidates for applications in biomedical engineering, smart sensors, sports and soft robotics. This paper aims to contribute to the existing gap in the study of auxetic metamaterials subjected to complex loading conditions, other than simple tension and compression, required for the mentioned applications.
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An, Siqi, Yajun Cao, and Hanqing Jiang. "A mechanically robust and facile shape morphing using tensile-induced buckling." Science Advances 10, no. 21 (May 24, 2024). http://dx.doi.org/10.1126/sciadv.ado8431.
Abstract:
Inspired by the adaptive mechanisms observed in biological organisms, shape-morphing soft structures have emerged as promising platforms for many applications. In this study, we present a shape-morphing strategy to overcome existing limitations of the intricate fabrication process and the lack of mechanical robustness against mechanical perturbations. Our method uses tensile-induced buckling, achieved by attaching restraining strips to a stretchable substrate. When the substrate is stretched, the stiffness mismatch between the restraining strips and the substrate, and the Poisson’s effect on the substrate cause the restraining strips to buckle, thereby transforming initially flat shapes into intricate three-dimensional (3D) configurations. Guided by an inverse design method, we demonstrate the capability to achieve complicated and diverse 3D shapes. Leveraging shape morphing, we further develop soft grippers exhibiting outstanding universality, high grasping efficiencies, and exceptional durability. Our proposed shape-morphing strategy is scalable and material-independent, holding notable potential for applications in soft robotics, haptics, and biomedical devices.
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Li, Tiantian, and Yaning Li. "3D Tiled Auxetic Metamaterial: A New Family of Mechanical Metamaterial with High Resilience and Mechanical Hysteresis." Advanced Materials, January 10, 2024. http://dx.doi.org/10.1002/adma.202309604.
Abstract:
AbstractFor artificial materials, desired properties often conflict. For example, engineering materials often achieve high energy dissipation by sacrificing resilience and vice versa, or desired auxeticity by losing their isotropy, which limits their performance and applications. To solve these conflicts, a strategy is proposed to create novel mechanical metamaterial via 3D space filling tiles with engaging key‐channel pairs, exemplified via auxetic 3D keyed‐octahedron–cuboctahedron metamaterials. This metamaterial shows high resilience while achieving large mechanical hysteresis synergistically under large compressive strain. Especially, this metamaterial exhibits ideal isotropy approaching the theoretical limit of isotropic Poisson's ratio, ‐1, as rarely seen in existing 3D mechanical metamaterials. In addition, the new class of metamaterials provides wide tunability on mechanical properties and behaviors, including an unusual coupled auxeticity and twisting behavior under normal compression. The designing methodology is illustrated by the integral of numerical modeling, theoretical analysis, and experimental characterization. The new mechanical metamaterials have broad applications in actuators and dampers, soft robotics, biomedical materials, and engineering materials/systems for energy dissipation.
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Wang, Jian-Peng, Da-Peng Li, Yu-Chen Liu, Lei Zhang, Zi-Yue Fu, Bing-Yu Liang, Si-Yue Yin, et al. "Comparison of learning curves and related postoperative indicators between endoscopic and robotic thyroidectomy: a systematic review and meta-analysis." International Journal of Surgery, June 21, 2024. http://dx.doi.org/10.1097/js9.0000000000001852.
Abstract:
Backgroud: Endoscopic thyroidectomy (ET) and robotic thyroidectomy (RT) yield similar perioperative outcomes. This study investigated how the learning curve (LC) affects perioperative outcomes between ET and RT, identifying factors that influence the LC. Materials and Methods: Two researchers individually searched PubMed, EMBASE, Web of Science, and Cochrane Library for relevant studies published until February 2024. The Newcastle-Ottawa Scale assessed study quality. Random effects model was used to compute the odds ratio and weighted mean difference (WMD). Poisson regression comparison of the number of surgeries (NLC) was required for ET and RT to reach the stable stage of the LC. Heterogeneity was measured using Cochran’s Q. Publication bias was tested using funnel plots, and sensitivity analysis assessed findings robustness. Subgroup analysis was done by operation type and patient characteristics. Results: This meta-analysis involved 33 studies. The drainage volume of ET was higher than that of RT (WMD=−17.56 [30.22, −4.49]). After reaching the NLC, the operation time of ET and RT was shortened (ET: WMD=28.15[18.04, 38.26]; RT: WMD=38.53[29.20, 47.86]). Other perioperative outcomes also improved to varying degrees. Notably, RT showed more refined central lymph node resection(5.67 vs. 4.71), less intraoperative bleeding (16.56 mL vs. 42.30 mL), and incidence of transient recurrent laryngeal nerve injury(24.59 vs. 26.77). The NLC of RT was smaller than that of ET(Incidence-rate ratios [IRR]=0.64[0.57, 0.72]). CUSUM analysis (ET: IRR=0.84[0.72, 0.99]; RT: IRR=0.55[0.44, 0.69]) or a smaller number of respondents (ET: IRR=0.26[0.15, 0.46]; RT: IRR=0.51[0.41, 0.63]) was associated with smaller NLC. In RT, transoral approach (IRR=2.73[1.96, 4.50]; IRR=2.48[1.61, 3.84]) and retroauricular approach (RAA) (IRR=2.13[1.26, 3.60]; IRR=1.78[1.04, 3.05]) had smaller NLC compared to bilateral axillo-breast and transaxillary approach (TAA). In ET, the NLC of RAA was smaller than that of TAA (IRR=1.61[1.04, 2.51]), breast approach(IRR=1.67[1.06, 2.64]), and subclavian approach(IRR=1.80[1.03, 3.14]). Conclusions: Rich surgical experience can improve surgical results of ET and RT. After reaching the NLC, the perioperative outcomes of RT are better than those of ET. Study subjects, surgical approaches, and analysis methods can affect NLC.
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Liu, Fengrui, Tatsuro Terakawa, Siying Long, and Masaharu Komori. "Rigid-foldable cylindrical origami with tunable mechanical behaviors." Scientific Reports 14, no. 1 (January 2, 2024). http://dx.doi.org/10.1038/s41598-023-50353-4.
Abstract:
AbstractRigid-foldable origami shows significant promise in advanced engineering applications including deployable structures, aerospace engineering, and robotics. It undergoes deformation solely at the creases during the folding process while maintaining rigidity throughout all facets. However, most types of cylindrical origami, such as Kresling origami, water-bomb origami, and twisted tower origami, lack rigid-foldability. Although shape transformation can be achieved through elastic folding, their limited rigid foldability constrains their engineering applications. To address this limitation, we proposed a type of cylindrical origami inspired by Kresling origami, named foldable prism origami (FP-ori), in this paper. FP-ori possesses not only rigid-foldability but also several tunable properties, including flat-foldability, self-locking, and bistability. The geometric properties of FP-ori were analyzed and the relationship between different parameters and tunable mechanical behaviors were verified through finite element method simulations, as well as experiments using paper models. Furthermore, we proposed stacked structures composed of multiple cubic FP-ori units, the rotation directions of which could be controlled through the combination arrangement. And drawing inspiration from kirigami, a negative Poisson’s ratio tessellation structure was created. These results indicated that FP-ori has substantial potential for broad application in engineering fields.
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Zhao, Fang, Yuzhan Li, Hong Gao, Ran Tao, Yiqi Mao, Yu Chen, Sheng Zhou, Jianming Zhao, and Dong Wang. "Design and Characterization of Deformable Superstructures Based on Amine‐Acrylate Liquid Crystal Elastomers." Advanced Science, November 9, 2023. http://dx.doi.org/10.1002/advs.202303594.
Abstract:
AbstractDeformable superstructures are man‐made materials with large deformation properties that surpass those of natural materials. However, traditional deformable superstructures generally use conventional materials as substrates, limiting their applications in multi‐mode reconfigurable robots and space‐expandable morphing structures. In this work, amine‐acrylate‐based liquid crystal elastomers (LCEs) are used as deformable superstructures substrate to provide high driving stress and strain. By changing the molar ratio of amine to acrylate, the thermal and mechanical properties of the LCEs are modified. The LCE with a ratio of 0.9 exhibited improved polymerization degree, elongation at break, and toughness. Besides an anisotropic finite deformation model based on hyperelastic theory is developed for the LCEs to capture the configuration variation under temperature activation. Built upon these findings, an LCE‐based paper‐cutting structure with negative Poisson's ratio and a 2D lattice superstructure model are combined, processed, and molded by laser cutting. The developed superstructure is pre‐programmed to the configuration required for service conditions, and the deformation processes are analyzed using both experimental and finite element methods. This study is expected to advance the application of deformable superstructures and LCEs in the fields of defense and military, aerospace, and bionic robotics.
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Bouguermouh, Karima, Mohamed Habibi, and Luc Laperrière. "4D printing of fiber-reinforced auxetic structures: the building blocks: A review." Smart Materials and Structures, May 2, 2024. http://dx.doi.org/10.1088/1361-665x/ad469d.
Abstract:
Abstract Four-dimensional (4D) printing has recently received much attention in the field of smart materials. It concerns using additive manufacturing to obtain geometries that can change shape under the effect of different stimuli. Such a technique enables the fabrication of 3D printed parts with the additional functionality of scalable, programmable, and controllable part shapes over time. 
This review provides a comprehensive examination of advances in the field of 4D printing, emphasizing the integration of fiber reinforcement and auxetic structures as crucial building blocks. 
The incorporation of fibers enhances structural integrity, while auxetic design principles contribute unique mechanical properties, such as negative Poisson's ratio and great potential for energy absorption due to their specific deformation mechanisms. Therefore, they present potential applications in aerospace, drones, and robotics.
The objective of this review article is first to describe the distinctive properties of shape memory polymers (SMPs), auxetic structures, and composite (fiber-reinforced) materials. A review of applications that use combinations of such materials is also presented when appropriate. The goal is to get a grip on the delicate balance between the different properties achievable in each case. The paper concludes by describing recent advances in 4D printing of fiber-reinforced auxetic structures.
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Tahidul Haque, A. B. M., Samuele Ferracin, and Jordan R. Raney. "Reprogrammable Mechanics via Individually Switchable Bistable Unit Cells in a Prestrained Chiral Metamaterial." Advanced Materials Technologies, May 30, 2024. http://dx.doi.org/10.1002/admt.202400474.
Abstract:
AbstractArchitected materials exhibit unique properties and functionalities based on the geometric arrangement of their constituent materials. In most cases, these parameters are fixed, requiring that the system be redesigned and reconstructed if different properties are desired. Both stimuli‐responsive materials and modular designs have been used to enable re‐programmable properties in the past, but often have limitations, such as the need for a continuous application of external stimuli or power, or unwanted global morphing. In this study, a locally stable anti‐tetra chiral (LSAT) metamaterial is introduced consisting of independently multistable units that can deform and change state without inducing changes in the global morphology. Adjacent cells are only weakly coupled, allowing the collective metamaterial to be switched between many different possible states. Local bistability enables re‐programmable heterogeneity, such as the snapping of cells along an edge or diagonally within the architected material. Utilizing finite element analysis (FEA), the influence of key geometric parameters on the re‐programmability of the metamaterials is systematically investigated. The effect of these parameters on properties such as shear stiffness, Poisson's ratio, and vibration are also investigated using experimental prototypes. This re‐programmable metamaterial promises to expand the design space for mechanical systems, with potential applications in non‐traditional computation, robotic actuation, and adaptive structures.
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Adhikari, Jitendra, Rajeev Kumar, Vikas Narain, and Satish Chandra Jain. "Electromechanical study of graphene reinforced lead-free functionally graded tile for vibration energy harvesting." Journal of Intelligent Material Systems and Structures, October 1, 2022, 1045389X2211219. http://dx.doi.org/10.1177/1045389x221121949.
Abstract:
This study focuses on the electromechanical analysis of functionally graded graphene reinforced piezoelectric composite (FG-GRPC) structures in order to identify circuit metrics such as voltage and power. The graphene platelets (GPLs) scatter evenly and parallelly in each graphene platelets reinforced piezoelectric composite (GRPC) tile. The effective modulus of elasticity for the GRPC tile is calculated by the Halpin-Tsai (HT) parallel model. The rule of the mixture (ROM) is employed to estimate the effective mass density, poisson’s ratio, and piezoelectric properties of GRPC structure. A simple power law distribution is responsible for the spatial disparity in composition over the thickness to generate FG-GRPC structural tiles. The first-order shear deformation theory and Hamilton’s principle are used to derive the governing finite element equations for the FG-GRPC plates. The impact of external resistance, frequency, volume fraction, piezoelectric characteristics, and geometry of the tile on the circuit metrics of FG-GRPC structures are thoroughly examined. Our results reveal that the circuit metrics of FG-GRPC plates are significantly enhanced due to consideration of material grading exponent and a small quantity of GPLs. This article will provide the necessary physical insights for modeling the electromechanical coupling in multipurpose piezoelectric materials, devices, and large-scale systems, allowing them to be used in industrial applications such as pressure sensors, miniature ultrasonic motors, fuel injectors, active controllers, and robotic systems.
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Lemire, Joe, Kate Chatfield‐Reed, Lindsay Kalan, Natalie Gugala, Connor Westersund, Henrik Almblad, Gordon Chua, and Raymond J. Turner. "Unravelling the myths and mysteries of the antimicrobial agent, silver." FASEB Journal 31, S1 (April 2017). http://dx.doi.org/10.1096/fasebj.31.1_supplement.939.2.
Abstract:
BackgroundSilver is being widely‐deployed in the clinic – in wound dressing, catheters, and endotracheal tubes ‐ to combat and control infectious disease. Despite this widespread use, we still don't know the precise way that silver kills the bacterial cell. Recently, our research group demonstrated that silver formulations with novel chemistries – silver oxysalts – have an enhanced antibacterial activity. Yet, we still don't know why different silver formulations show variable antimicrobial efficacy.MethodsTo test the efficacy of various silver compounds, numerous strains of E.coli, P.aeruginosa, and S.aureus were grown as single and multispecies biofilms in the Calgary Biofilm Device. The capacity of different silver compounds to prevent the formation of and eradicate planktonic and biofilm populations of bacteria was performed using the minimal biofilm eradication concentration assay, confocal microscopy and crystal violet staining. To enhance our understanding of how silver poisons bacteria, we undertook a robotic chemical genetic screen of an ordered mutant library of E.coli bacteria – the Keio collection. To confirm the genetic linkage of our silver responsive genes identified in our chemical genetic screen, we used Scarless Cas‐9 Assisted Recombineering to generate unmarked mutants. Our genes of interest were then linked to silver sensitivity or resistance phenotypes using minimal inhibition concentration assays and transmission electron microscopy (TEM).ResultsWe observed that higher oxidation states of silver have enhanced activity for preventing the formation of, and eradicating single and multispecies, planktonic and biofilm, populations of bacteria – suggesting that the chemistry of silver formulations dictates its antimicrobial efficacy. Our chemical genetic screen suggests that silver poisoning has previously unanticipated effects on the bacterial cell including disrupting the bacterial cell envelope, altering indole metabolism, and controlling bacterial cell population. Moreover, using a Recombineering workflow and TEM we confirmed the involvement of a gene involved in the production of a cell wall protein, and a monovalent cation transporter, in silver sensitivity and resistance, respectively. The latter finding is relevant because the protein responsible for the entrance of silver into the bacterial cell has yet to be identified.ConclusionsAltogether, our findings established novel mechanisms regarding the mode‐of‐action of silver in the bacterial cell. We've established that the specific chemistries of silver compounds determine antimicrobial capacity. Additionally, we've identified genes that may lead to silver resistance. These findings are ever‐important as we aim to maintain the utility of this valuable antimicrobial agent.Support or Funding InformationWe graciously acknowledge funding from the Natural Science and Engineering Research Council of Canada and the Canadian Institutes of Health Research. JL was funded by a Banting Postdoctoral Fellowship and an Alberta Innovates Health Solutions Postdoctoral award. We would also like to thank the University of Calgary for providing an Eyes High Graduate/Postgraduate Fellowship to NG and HA, respectively and research funding for JL.