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Detection of Graphene Cracks By Electromagnetic Induction, Insensitive to Doping Level
Get PDFDetection of cracks is a great concern in production and operation processes of graphene based devices to ensure uniform quality. Here, we show a detection method for graphene cracks by electromagnetic induction. The time varying magnetic field leads to induced voltage signals on graphene, and the signals are detected by a voltmeter. The measured level of induced voltage is correlated with the number of cracks in graphene positively. The correlation is attributed to the increasing inductive characteristic of defective graphene, and it is verified by electromagnetic simulation and radio frequency analysis. Furthermore, we demonstrate that the induced voltage signal is insensitive to the doping level of graphene. Our work can potentially lead to the development of a high-throughput and reliable crack inspection technique for mass production of graphene applications
Thickness Effect of Nanocrystalline Layer on the Deformation Mechanism of Amorphous/Crystalline Multilayered Structure
Get PDFDifferent thickness of amorphous/nanocrystalline multi-layered structure can be used to modulate the strength and ductility of the composite materials. In this work, molecular dynamics simulations were conducted to study the thickness effect of nanocrystalline layer on mechanical properties and deformation behavior of the Cu64Zr36/Cu multi-layer structure. The stress-strain relationship, local stress, local strain, and deformation mechanism are investigated. The results reveal that the change of thickness of the crystalline layer significantly affects the mechanical properties and deformation behavior. As the strain at the elastic region, the amorphous Cu64Zr36 layer dominates the mechanical behavior, leading the fact that Young’s modulus, first yielding stress, and first yielding strain are close to that of Cu64Zr36 BMG. As the strain at the plastic region, the contribution of the crystalline layer on the mechanical behavior becomes more and more significant with increasing the thickness of the crystalline layer. For the thickness ratio (amorphous/crystalline) of 4, the shear band deformation of amorphous layer dominates the mechanical properties. For the thickness ratio is 1, the glide dislocation of the crystalline layer dominates the stress-strain behavior
Overview of Computational Modeling in Nano/Micro Scaled Thin Films Mechanical Properties and Its Applications
Get PDFThis research reviews the application of computational mechanics on the properties of nano/micro scaled thin films, in which the application of different computational methods is included. The concept and fundamental theories of concerned applications, material behavior estimations, interfacial delamination behavior, strain engineering, and multilevel modeling are thoroughly discussed. Moreover, an example of an interfacial adhesion estimation is presented to systematically estimate the related mechanical reliability issue in the microelectronic industry. The presented results show that the peeled mode fracture is the dominant delamination behavior of layered material system, with high stiffness along the bonding interface. However, the shear mode fracture being dominated as the polymer cover plate with low moduli is considered. The occurrence of crack advance is also significantly influenced by the interfacial crack length and applied loading. Therefore, this paper could serve as a guideline of several engineering cases with the assistance of computational mechanics
A Layer-Based Mesh Generator and Scheme for 3D Printing Simulation
Get PDF3D Printing, also called Additive Manufacturing, has become a promising manufacturing method to produce parts in various fields as it can produce parts even with very irregular shapes in a relatively shorter process and time. However, during the printing process, some problems could decrease the accuracy and quality of the printed parts, such as warpage due to thermal strains, deformation due to inadequate supports, etc. The finite element method is most commonly adopted to evaluate engineering problems in advance to reduce possible failures; however, the element meshes, needed for analyses, are always irregularly distributed, especially for irregular objects, and cannot match the layer-by-layer growing shapes of the printed parts in the 3D printing process. Without a proper element mesh, the analysis cannot be performed. To overcome this problem, a layer-based mesh generator combined with a corresponding scheme for the 3D Printing simulation is proposed and developed. With the proposed methods, the analysis models can be designed and generated to match the growing shapes, i.e., layer-by-layer, and used to simulate the layer-by-layer growing behavior in the 3D printing process. Moreover, the proposed schemes directly adopt the Stereo-Lithography (STL) formatted geometric data as the geometry model on which the mesh generation and simulation are based. This makes them even easier to use since the STL geometry format is a De facto standard format used in the 3D printing industry. Several simulation cases have been conducted to demonstrate the effectiveness and efficiency of these proposed schemes
A New NTRU-Type Public-Key Cryptosystem over the Binary Field
Get PDFAs the development of cloud computing and the convenience of wireless sensor netowrks, smart devices are widely used in daily life, but the security issues of the smart devices have not been well resolved. In this paper, we present a new NTRU-type public-key cryptosystem over the binary field. Specifically, the security of our scheme relies on the computational intractability of an unbalanced sparse polynomial ratio problem (DUSPR). Through theoretical analysis, we prove the correctness of our proposed cryptosystem. Furthermore, we implement our scheme using the NTL library, and conduct a group of experiments to evaluate the capabilities and consuming time of encryption and decryption. Our experiments result demonstrates that the NTRU-type public-key cryptosystem over the binary field is relatively practical and effective
Directional Antenna Intelligent Coverage Method Based on Traversal Optimization Algorithm
Get PDFWireless broadband communication is widely used in maneuver command communications systems in many fields, such as military operations, counter-terrorism and disaster relief. How to reasonably formulate the directional antenna coverage strategy according to the mobile terminal dynamic distribution and guide the directional antenna dynamic coverage becomes a practical research topic. In many applications, a temporary wireless boardband base station is required to support wireless signal communications between many terminals from nearby vehicles and staffs. It is therefore important to efficiently set directional antenna while ensuring large enough coverage over dynamically distributed terminals. The wireless broadband base station mostly uses two rotatable conical-polarized directional antennas with a coverage angle of 80 degrees. In this paper, we study this directional antenna coverage problem and propose a new solution by using three-dimensional coordinate transformation, provides wireless signal coverage schemes for point-to-point and point-to-region, determined the required horizontal rotation angle and pitch rotation angle of the directional antenna intelligent coverage, which lays the foundation for the performance of the wireless broadband communication in the maneuver command communication system
Theoretical Implementation of All-Optical XOR Gate at 160 Gb/s Using Semiconductor Optical Amplifiers-Based Turbo-Switched Mach-Zehnder Interferometer
Get PDFThe implantation of an all-optical eXclusive-OR (XOR) gate run at 160 Gb/s using semiconductor optical amplifiers (SOAs)-based turbo-switched Mach-Zehnder interferometer (TS-MZI) is theoretically investigated and verified. The dependence of the quality factor (QF) on the signal and SOA key operating parameters is examined and assessed, including the impact of amplified spontaneous emission in order to obtain realistic results. A higher QF is obtained when using SOAs-based TS-MZI than when using conventional SOAs-based MZI
Characterizing the Mechanical Variations of Human Femoropopliteal Artery During Aging Process
Get PDFVascular diseases during aging process are closely correlated to the age-related changes of mechanical stimuli for resident cells. Characterizing the variations of mechanical environments in vessel walls with advancing age is crucial for a better understanding of vascular remodeling and pathological changes. In this study, the mechanical stress, strain, and wall stiffness of the femoropopliteal arteries (FPAs) were compared among four different age groups from adolescent to young, middle-aged, and aged subjects. The material parameters and geometries adopted in the FPA models were obtained from published experimental results. It is found that high mechanical stress appears at different layers in young and old FPA walls respectively. The characteristics of the middle-aged FPA wall suggests that it is the most capable of resisting high blood pressures and maintaining a mechanical homeostasis during the entire life span. It is demonstrated that the variations of stress and strain rather than that of wall stiffness can be used as an indicator to illustrate the profile of FPA aging. Our results could serve as an age-specific mechanical reference for vascular mechanobiological studies, and allow further exploration of cellular dysfunctions in vessel walls during aging process
Sanguinarine Decreases Cell Stiffness and Traction Force and Inhibits the Reactivity of Airway Smooth Muscle Cells in Culture
Get PDFAirway hyperresponsiveness (AHR) is the cardinal character of asthma, which involves the biomechanical properties such as cell stiffness and traction force of airway smooth muscle cells (ASMCs). Therefore, these biomechanical properties comprise logical targets of therapy. β2-adrenergic agonist is currently the mainstream drug to target ASMCs in clinical practice for treating asthma. However, this drug is known for side effects such as desensitization and non-responsiveness in some patients. Therefore, it is desirable to search for new drug agents to be alternative of β2-adrenergic agonist. In this context, sanguinarine, a natural product derived from plants such as bloodroots, that has been reported to relax gut smooth muscle emerges as a potential candidate. So far, it is unknown whether sanguinarine can regulate the biomechanical properties of ASMCs and reactivity of ASMCs to irritants. Thus, we tested the hypothesis that sanguinarine reduce the contractile potentials of ASMCs in culture. To do so, the primary cultured rat ASMCs were first treated with different concentration of sanguinarine. Then, cell stiffness, traction force, fiber distribution, and calcium signaling of the ASMCs were evaluated by optical magnetic twisting cytometry, Fourier transform traction microscopy, atomic force microscopy, and Fluo-4/AM based fluorescence confocal scanning microscopy, respectively. The results indicated that sanguinarine (0.05 and 0.5 μmol/L) significantly decreased cell stiffness and traction force, inhibited reactivity of ASMCs to histamine, and disrupted the fiber structures in ASMCs in dose-dependent manner. These findings establish that sanguinarine can indeed change the biomechanical properties of ASMCs and may be used to treat AHR in asthma
Warmest Congratulations to Dr. Yuan-Cheng Fung at His Centennial Celebration
Get PDFProfessor Y.C. Fung has made tremendous impacts on science, engineering and humanity through his research and its applications, by setting the highest standards, through educating many students and their students, and providing his exemplary leadership. He has applied his profound knowledge and elegant analytical methods to the study of biomedical problems with rigor and excellence. He established the foundations of biomechanics in living tissues and organs. Through his vision of the power of “making models” to explain and predict biological phenomena, Dr. Fung opened up new vista for bioengineering, from organs-systems to molecules-genes, and has provided the foundation of research activities in many institutions in the United States and the world. He has made outstanding contributions to education in bioengineering, service to professional organizations, and translation to industry and clinical medicine. He is widely recognized as the Father of Biomechanics and the leading Bioengineer in the world. His extraordinary achievements and commands in science, engineering and the arts make him a Renaissance Man for the world