Twinning and the mechanical behavior of magnesium alloys at very high strain rates

The dynamic mechanical behavior of magnesium and its alloys is a subject of interest primarily because of its high specific strength. This makes it attractive for structural components and vehicles. The hexagonal close packed crystal structure of magnesium makes it highly anisotropic in terms of its mechanical behavior. Extension twinning is a dominant deformation mechanism in these materials. This is often reflected in a characteristic sigmoidal profile of the stress–strain curve when crystals are compressed along directions perpendicular to the crystallographic c-axis. Past experiments have been limited to strain rates of 103 s–1 . This study focuses on microstructural twinning effects on the mechanical behavior of AZ31 magnesium alloy at higher strain rates. We perform very high-strain rate experiments on AZ31 magnesium alloy, using a miniature Kolsky compression bar apparatus coupled with a high speed camera for whole field imaging. This experiment is capable of achieving strain rates on the order of 105 s–1 . Experiments at these strain rates have shown substantial plastic deformation without failure when compared with the lower rates of loading. This is evidence of deformation mechanisms that tend to delay failure in the material. We also observe a change in the hardening rates between these experiments and experiments done at 103 s–1. Examination of the microstructure of deformed samples gives us information about the relative activation and growth of deformation mechanisms that cause plastic deformation at these rates

A Real Time Image Fusion based Framework for Concealed Weapon Detection

In this paper, a well-organized hidden weapon detection (CWD) algorithm based on image fusion is presented. First, the images obtained consumingdissimilar sensors are decomposed into low and high occurrence bands with the double-density dualtree compound wavelet transform (DDDTCWT). Then two novel decision methods are introduced referring to the appearances of the frequency bands, which meaningfully improves the image fusion performance. The fusion of low frequency bands coefficients is strong-minded by the local contrast, while the high occurrence band fusion rule is developed by considering both the texture feature of HVS and the local energy basis. Finally, the fused image is attained through the inverse DDDTCWT. Experiments and comparisons establish the robustness and efficiency of the proposed approach and indicate that the fusion rules can be applied to different multi-scale transforms. Also, our work shows that the mixture result using the proposed fusion rules on DDDTCWT is superior to other mixtures as well as previously proposed approaches

Synchrophasor Technology for Cyber Security in Smart Grid

Smart grid is controlled by an authority personnel who uses LAN or the internet to control it. By knowing this information any one from outside can control the smart grid using LAN or the internet. This process of hacking the smart grid control is known as aurora attack. The Aurora attack may pose a risk to rotating machinery operating under certain conditions on the electrical grid. The Aurora attack involves opening and closing one or more circuit breakers, resulting in an out-of-synchronism condition that may damage rotating equipment connected to the power grid.This paper focuses on the Aurora attack on a synchronous generator and the existing technology available to mitigate the attack. The root cause of the vulnerability is breakdown in security. The first level prevents the attack with sound security practices. The second level protects the equipment in the event that the security level is compromised. The equipment can be protected using wide-area synchronized phasor measurement and protection system and security considerations

Corrigendum: Systemic contact dermatitis related to alcoholic beverage consumption

The original article was published on September 15, 2019 and corrected on November 15, 2019.The revised version of the article adds a missing author. This change appears in the revised online PDF copy of this article

HERMITIAN SYMMETRY BASED FIBER NON-LINEARITY COMPENSATION IN OPTICAL OFDM NETWORKS

Orthogonal Frequency Division Multiplexing (OFDM) is a modulation technique which is now used in most new and emerging broadband wired and wireless communication systems such as standard 802.11a/b/g/n, Digital Video Broad casting Television (DVB-TV), and Long Term Evolution (LTE) in the next mobile generation, due to its capacity in solving the problems of Inter-Symbol Interference (ISI) caused by the effects of the dispersive channel. Very recently researches focus on applying OFDM technology in optical fiber communication systems. Optical OFDM is well suited for high speed transmission systems with high spectral efficiency and attracted significant attention from the optical communication community. One of the major issues that degrade the performance of optical OFDM networks is its fiber non-linearity. Fiber non-linearities represent the fundamental limiting mechanisms to the amount of data that can be transmitted on a single optical fiber. Non-linear effects arise as optical fiber data rates, transmission lengths, number of wavelengths, and optical power level increases. Therefore, the effect of non-linearity in high data rate optical networks needs to be controlled to enhance link performances. In this paper, a nonlinearity compensation technique (Hermitian Symmetry) is implemented to improve the performance of OFDM based optical networks. This would provide high spectral efficiency, low ISI and very good Bit Error Rate (BER) performances without increasing the complexity of the network. The optical OFDM transmission system with fiber non-linearity compensation is simulated using Virtual Photonics Integrated (VPI) software

Investigation on Tensile and Flexural Strength of KOH Treated Ridge Gourd Fiber-Polyester Resin Composite

Abstract- Natural fiber is abundantly availing in nature. Nowadays this is used in composite materials. In general ridge gourd fiber is very strength material due to its woven. So this fiber is using in composites. Here potassium hydroxide (KOH) treated ridge gourd fiber is used in composite. One of the traditional methods, hand lay – up method is to use for preparing ridge gourd fiber reinforcing polyester composite. Specimens are to be test as per ASTM standards. Tensile and flexural strength are analyzed and optimize the parameters. Then, the fractured surfaces are analyzed with the help of SEM images. DOI: 10.17762/ijritcc2321-8169.150312

Content-Adaptive Variable Framerate Encoding Scheme for Green Live Streaming

Adaptive live video streaming applications use a fixed predefined configuration for the bitrate ladder with constant framerate and encoding presets in a session. However, selecting optimized framerates and presets for every bitrate ladder representation can enhance perceptual quality, improve computational resource allocation, and thus, the streaming energy efficiency. In particular, low framerates for low-bitrate representations reduce compression artifacts and decrease encoding energy consumption. In addition, an optimized preset may lead to improved compression efficiency. To this light, this paper proposes a Content-adaptive Variable Framerate (CVFR) encoding scheme, which offers two modes of operation: ecological (ECO) and high-quality (HQ). CVFR-ECO optimizes for the highest encoding energy savings by predicting the optimized framerate for each representation in the bitrate ladder. CVFR-HQ takes it further by predicting each representation's optimized framerate-encoding preset pair using low-complexity discrete cosine transform energy-based spatial and temporal features for compression efficiency and sustainable storage. We demonstrate the advantage of CVFR using the x264 open-source video encoder. The results show that CVFR-ECO yields an average PSNR and VMAF increase of 0.02 dB and 2.50 points, respectively, for the same bitrate, compared to the fastest preset highest framerate encoding. CVFR-ECO also yields an average encoding and storage energy consumption reduction of 34.54% and 76.24%, considering a just noticeable difference (JND) of six VMAF points. In comparison, CVFR-HQ yields an average increase in PSNR and VMAF of 2.43 dB and 10.14 points, respectively, for the same bitrate. Finally, CVFR-HQ resulted in an average reduction in storage energy consumption of 83.18%, considering a JND of six VMAF points

Development and Airworthiness Certification of the Ti6Al4V Inlet Casing Inner Forging

The inlet casing inner has manufactured using Ti-6Al-4V alloy through a closed die-forging route. It undergoes cyclic loads in addition to operating in extreme conditions in high-temperature environments. The demanding mission requirement of these engines necessitates the inlet casing inner to be flawless throughout its life cycle while retaining its structural integrity. It makes the qualification for airworthiness of the casing, a daunting task. In addition, the qualification tests also help to evaluate the design and manufacturing processes (closed die forging) of the inlet casing inner. The tests also provide data for further improvement of the inlet casing inner in terms of strength and fatigue life. It helps to ensure that the inlet casing inner will be able to perform as expected throughout its operational life. All the batch and consolidated test results comply with the relevant ASTM, MIL standards, and test schedule requirements