Hidden Markov models combining discrete symbols and continuous attributes in handwriting recognition

Prior arts in handwritten word recognition model either discrete features or continuous features, but not both. This paper combines discrete symbols and continuous attributes into structural handwriting features and model, them by transition-emitting and state-emitting hidden Markov models. The models are rigorously defined and experiments have proven their effectiveness.     

Ionic Silicon Protects Oxidative Damage and Promotes Skeletal Muscle Cell Regeneration

Volumetric muscle loss injuries overwhelm the endogenous regenerative capacity of skeletal muscle, and the associated oxidative damage can delay regeneration and prolong recovery. This study aimed to investigate the effect of silicon-ions on C2C12 skeletal muscle cells under normal and excessive oxidative stress conditions to gain insights into its role on myogenesis during the early stages of muscle regeneration. In vitro studies indicated that 0.1 mM Si-ions into cell culture media significantly increased cell viability, proliferation, migration, and myotube formation compared to control. Additionally, MyoG, MyoD, Neurturin, and GABA expression were significantly increased with addition of 0.1, 0.5, and 1.0 mM of Si-ion for 1 and 5 days of C2C12 myoblast differentiation. Furthermore, 0.1–2.0 mM Si-ions attenuated the toxic effects of H₂O₂ within 24 h resulting in increased cell viability and differentiation. Addition of 1.0 mM of Si-ions significantly aid cell recovery and protected from the toxic effect of 0.4 mM H₂O₂ on cell migration. These results suggest that ionic silicon may have a potential effect in unfavorable situations where reactive oxygen species is predominant affecting cell viability, proliferation, migration, and differentiation. Furthermore, this study provides a guide for designing Si-containing biomaterials with desirable Si-ion release for skeletal muscle regeneration.     

All‐Dielectric Active Terahertz Photonics Driven by Bound States in the Continuum

The remarkable emergence of all‐dielectric meta‐photonics governed by the physics of high‐index dielectric materials offers a low‐loss platform for efficient manipulation and subwavelength control of electromagnetic waves from microwaves to visible frequencies. Dielectric metasurfaces can focus electromagnetic waves, generate structured beams and vortices, enhance local fields for advanced sensing, and provide novel functionalities for classical and quantum technologies. Recent advances in meta‐photonics are associated with the exploration of exotic electromagnetic modes called the bound states in the continuum (BICs), which offer a simple interference mechanism to achieve large quality factors (Q) through excitation of supercavity modes in dielectric nanostructures and resonant metasurfaces. Here, a BIC‐driven terahertz metasurface with dynamic control of high‐Q silicon supercavities that are reconfigurable at a nanosecond timescale is experimentally demonstrated. It is revealed that such supercavities enable low‐power, optically induced terahertz switching and modulation of sharp resonances for potential applications in lasing, mode multiplexing, and biosensing.     

Monitoring of Fatigue in Welded Beams Using Piezoelectric Wafer Based Impedance Technique

Real-life aerospace and mechanical structures are mostly prone to fatigue, which is the occurrence of localized but progressive damage due to continuous fluctuating stresses. Fatigue damage can be monitored by observing changes in the structural stiffness resulting from strength reduction as a function of the number of loading cycles. The problem is more severe if the welds are subjected to such fatigue behavior. This paper employed non-destructive testing (NDT) method such as dye-penetrant and advanced NDT method such as the piezoelectric wafer based electromechanical impedance (EMI) technique to study the fatigue behavior of fillet welds in three specimens. Two specimens were tested in one single day, whereas the third on three consecutive days by unloading the specimen at the end of each day. Generally in laboratory, fatigue test is conducted by continuous cyclic loading/unloading till failure. However, the third specimen was subjected to intermittent fatigue to understand the stiffness changes which are due to the crack and its growth, or material realignment and partial strength restoration. Furthermore, cracks leading to failure are captured using EMI based signature analysis in these specimens. The signatures were further analyzed using statistical index, numerical modeling and peak shift measurements. The uniqueness of this paper is to present a comprehensive study of both load and non-load carrying welds by means of intermittent fatigue tests, using a thorough admittance signature analysis. The major observation of this study is that the fatigue behavior can be viewed as fusion of axial and transverse load changes coupled with crack severity, as observed from signatures.     

Influence of injection timing on the performance,combustion and emission characteristics of diesel engine powered with tamarind seed biodiesel blend

ABSTRACT

The limitations and ramifications of petroleum fuel on the present environmental society raised the necessity of alternative fuel. The physicochemical properties of biodiesel and its ability to reduce emissions have engaged the attention of researchers to prefer biodiesel as a better alternative fuel. A modification in engine parameters is proven to be one of the best techniques to obtain comparable results with diesel. The following study emphasises TSME 20 (20% Tamarind Seed Methyl Ester with 80% diesel) as an alternative fuel and its performance and emission characteristics are deciphered at different injection timings (19°, 23° and 27° bTDC) at different loads. Focusing on the results obtained at full-load condition, considerable improvement in brake thermal efficiency by 3.18% was noticed with the significant reduction in carbon monoxide, hydrocarbon, oxides of nitrogen and smoke by 17.3%, 57.3%, 31.34% and 8.1%, respectively, at retarded injection timing compared to standard injection timing.     

Insight of electrical behavior in ferroelectric‐semiconductor polymer nanocomposite films of PVDF/ZnSe and PVDF/Cu:ZnSe

Nanocomposite thin films (NCTF) of low‐dimensional ZnSe and copper doped ZnSe integrated poly(vinylidene fluoride) (PVDF) polymer were developed via simple solution casting method. Herein, ZnSe and Cu:ZnSe nanoparticles were synthesized through the chemical reduction technique. The obtained low‐dimensional nanoparticles and NCTFs were characterized by XRD, SEM/EDS, TEM, and FTIR analysis. Room temperature dielectric and ferroelectric characteristics of PVDF/ZnSe flexible NCTF exhibited superior dielectric and ferroelectric behavior with a high coercive field of 15.6 V. Whereas, the dielectric and ferroelectric characteristics were greatly diminished in the PVDF/Cu:ZnSe flexible NCTF was due to the conducting behavior of copper ions at the interface of the polymer network. These results indicated that the PVDF/ZnSe flexible NCTF will be a potential candidate for advanced electrical applications and device fabrication. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44983.     

Applying location estimation for reliable routing in tactical unmanned ground vehicle networks

An unmanned ground vehicle (UGV) network operates as an ad hoc autonomous tactical network. In this paper, we study the deployment of a UGV network and its ability to use location estimation to provide reliable data forwarding. This analysis involves (1) location estimation to obtain realistic estimates of the node’s (UGV) spatial positions and (2) real-time path planning to obtain reliable routing among nodes using the estimates of the node positions. Conventional approaches commonly use the popular Random Waypoint (RWP) model (or its variants) as the mobility model. The RWP approach uses randomly selected node positions and has no way to cope with nodes moving in and out of transmission range. These deficiencies cause the route reliability to suffer. Our approach (1) uses an Extended Kalman Filter (EKF) for node mobility/location estimation and (2) uses a modified Ad Hoc On Demand Distance Vector (AODV) algorithm for route selection using a new routing parameter called contact time. We refer to this combined approach as the AODV-LocPred algorithm. We compare the AODV-LocPred algorithm with AODV using the RWP model. This is referred to as AODV-RWP. Our simulations show that the AODV-LocPred algorithm significantly outperforms the AODV-RWP algorithm in terms of packet delivery ratio (PDR), because it provides realistic node position estimates and it copes in a reasonable way with nodes moving in and out of transmission range. However, the AODV-LocPred incurs an increase in end-to-end delay. Nonetheless, we expect that in many real-world settings, this tradeoff is acceptable.     

Optimal flow control for utility-lifetime tradeoff in wireless sensor networks

In this paper, we study the utility-lifetime tradeoff in wireless sensor networks (WSNs) by optimal flow control. We consider the flow control in a more practical way by taking into account link congestion and energy efficiency in our network model, and formulate it as a constrained multi-objective optimization problem. Because of the variable coupling in the objective function, auxiliary variables are introduced to decouple it. We introduce the concept of inconsistent coordination price to balance the energy consumption of the sensor nodes. Based on the congestion price and inconsistent coordination prices, a distributed algorithm using gradient projection is proposed to solve the optimization problem. The convergence of the algorithm is also proved. Numerical results show the convergence of our algorithm, the tradeoff of utility and lifetime, as well as the necessity of considering link congestion in WSNs.