Experimental investigation on low energy impact behavior of foam cored sandwich composites

This study focuses on an experimental investigation of damage tolerance of the foam cored sandwich composite subjected to low energy impact. Tests are performed to correlate delamination length with failure loads and loss of damage tolerance of the sandwich composite. The impact force history is used to determine momentum imparted to the specimen, the work done on the specimen, and the kinetic energy in order to gain an understanding of the mechanisms involved in damage due to impact loading.     

Neural network applications for jamming state information generator

A known jamming state information (JSI) scheme for a coded frequency-hopped M-ary frequency-shift-keying (FH/MFSK) system under partial-band noise jamming, plus additive white Gaussian noise, utilizes the maximum a posteriori (MAP) rule based on the total energy received in the M-tone signaling bands. It is assumed that the knowledge of partial-band noise jamming fraction is available to the JSI generator. Because this scheme reduces the M-dimensional information into one dimension, i.e., the total energy, the generated JSI may not be the best. In this paper, a neural network approach to the JSI generation is presented. The efficiency of the new JSI generator with known partial-band noise jamming fraction is compared with the MAP generator. The neural network scheme is then generalized to increase its robustness by allowing for an unknown partial-band noise jamming fraction. The neural network JSI generator with or even without knowledge of jamming fraction offers significantly better performance for a coded FH/MFSK communication system than the MAP JSI generator for high code rate.     

Real-time fiber optic network for an integrated digital protectionand control system

The authors present a real-time network using an optical-fiber transmission line and implement the prototype network system for a proposed integrated digital protection and control system. A single network structure is investigated which supports both protection and control functions. It realizes high-speed communications among the power equipment. As a communication protocol the IEEE 802.4 token passing bus protocol with fiber-optic medium is employed, taking substation environments into account. Two implementation schemes for the communication scheme are suggested which are based on the IEEE 802.4 specifications. An allocation method is presented for setting the network parameter and some performance indices are analyzed. Through the experiments, it is shown that the proposed prototype network system satisfies the necessary requirements in substations     

Bright-Multicolor,Highly Efficient,and Addressable Phosphorescent Organic Light-Emitting Fibers: Toward Wearable Textile Information Displays

Fiber-based light-emitting devices, which can be directly integrated into daily clothes, have emerged as a next-generation display form factor that can provide informational hyper-connections between humans and devices. However, although various approaches have provided advanced wearability, challenges remain for visualizing information, such as high power consumption resulting from high driving voltage and low current efficiency (CE), limited brightness making information difficult to recognize, and lack of addressability for displaying information. Here, a novel fiber-based textile display that can surmount those challenges by successfully introducing phosphorescent organic light-emitting diodes (phOLEDs) based on a dip-coating method and an addressable structure on cylinder-shaped fiber is reported. The fiber phOLEDs exhibit unprecedented optoelectronic performance, including brightness, CE, and driving voltages comparable to those of conventional glass-based OLEDs. Particularly, they show the highest CE values of 16.3, 60.7, and 16.9 cd A^–1 for red, green, and blue, respectively, among results reported thus far. Also, the fiber phOLEDs with an addressable structure implementing independent pixels can be operated by the matrix-addressable scheme. Based on unique deformability which is confirmed by flexibility tests, the performance capabilities, and addressability, letter information can be successfully visualized on daily clothes, demonstrating the potential for realizing truly wearable textile displays.     

Metal–Organic Framework‐Derived Graphitic Nanoribbons Anchored on Graphene for Electroionic Artificial Muscles

To achieve large bending displacement and fast response time under ultralow input voltages, as well as improved durability, advanced high‐performance ionic actuators still face crucial design challenges that must be resolved. Here, hierarchically porous and unzipped graphitic nanoribbons anchored on graphene as an efficient electrode material for high‐performance electroionic artificial muscles are reported. Using controlled solvothermal and pyrolysis methods, nanoarchitectured carbon is derived from a self‐templated potassium‐based metal–organic frameworks–graphene hybrid. The newly designed ionic actuator demonstrates excellent actuation performance, including large bending displacement (17.4 mm) and a strain difference of 0.51% at 0.5 V AC input, very fast response time (700 ms) at 0.5 V DC input, wide frequency response (0.1–15 Hz), and excellent cycling stability (92%) after 25 000 cycles without any delamination of electrodes under continuous electrical operation. The breakthrough in actuation performance mainly stems from the unzipping of hollow nanorods to hierarchical porous graphitic nanoribbons anchored on graphene with the enlarged surface area, large pore volume, stronger mechanical integrity, and emerging charge storage and transport ability. Further, the electroionic actuator shows promise when applied in the demonstration of a biomimicking Venus flytrap.     

Determining speaker attributes from stress-affected speech in emergency situations with hybrid SVM-DNN architecture

Multimedia Tools and Applications - In the millions of emergency reporting calls made each year, about a quarter are non-emergencies. To avoid responding to such situations, forensic examination of...     

Characterisation of unbound aggregate materials considering physical and morphological properties

The objective of this paper is to evaluate the factors affecting resilient and permanent deformation behaviour of unbound granular materials, with a focus on the aggregate physical and morphological characteristics. To evaluate the behaviour of base course, repeated load triaxial testing is commonly used to establish the stress-dependent resilient modulus properties of unbound aggregate base and subbase materials. Although resilient modulus of aggregates is a critical input into mechanistic-empirical pavement design methods, the resilient modulus of unbound base material is often estimated from empirical correlations with index properties in the AASHTOWare Pavement ME design procedure for its simplicity. Since actual field stress conditions and resilient modulus stress states are generally quite different from those generated in the empirical test methods, use of an empirical correlation could lead to an unreliable prediction of resilient modulus and permanent deformation. In order to properly assess the stability of an unbound aggregate layer, it is necessary to establish a proper process to understand the factors affecting fundamental and performance-related properties of unbound granular materials. In this study, aggregate samples from four different sources were tested for resilient modulus and Poisson’s ratio measurements using the Precision Unbound Material Analyzer equipment. Morphological or shape properties of aggregate samples were also measured using an image analysis device. The results demonstrate that aggregate physical and morphological properties affect aggregate resilient and permanent deformation. Further, it is suggested that the resilient modulus of the aggregate should not be used as the sole indicator of rutting performance of aggregate base.     

Camphor‐Enabled Transfer and Mechanical Testing of Centimeter‐Scale Ultrathin Films

Camphor is used to transfer centimeter‐scale ultrathin films onto custom‐designed substrates for mechanical (tensile) testing. Compared to traditional transfer methods using dissolving/peeling to remove the support‐layers, camphor is sublimed away in air at low temperature, thereby avoiding additional stress on the as‐transferred films. Large‐area ultrathin films can be transferred onto hollow substrates without damage by this method. Tensile measurements are made on centimeter‐scale 300 nm‐thick graphene oxide film specimens, much thinner than the ≈2 μm minimum thickness of macroscale graphene‐oxide films previously reported. Tensile tests were also done on two different types of large‐area samples of adlayer free CVD‐grown single‐layer graphene supported by a ≈100 nm thick polycarbonate film; graphene stiffens this sample significantly, thus the intrinsic mechanical response of the graphene can be extracted. This is the first tensile measurement of centimeter‐scale monolayer graphene films. The Young's modulus of polycrystalline graphene ranges from 637 to 793 GPa, while for near single‐crystal graphene, it ranges from 728 to 908 GPa (folds parallel to the tensile loading direction) and from 683 to 775 GPa (folds orthogonal to the tensile loading direction), demonstrating the mechanical performance of large‐area graphene in a size scale relevant to many applications.