Apatite formation and weight loss study in EDMed perforated AZ31 Mg-alloy

Porous structures are highly preferred for bone regeneration and high tissue in-growth.In present work,electrical discharge drilling(EDD),a thermal erosion process was used to produce through holes in Mg-alloys to fabricate perforated structure similar to open cell porous structure in extruded AZ31.Apatite formation and weight loss study was conducted for 7 days,14 days and 21 days after immersion tests in SBF solution.The perforated structure in AZ31 with 26 through micro-holes provides 72%increase in surface area but with marginally 4%higher weight loss as compare to non-perforated structure.Comparing perforated and non-perforated samples of Mg-alloy,it was well observed that perforated structure forms high volume of apatite as compared to non-perforated structure.Scanning electron microscopic(SEM)study revealed that in perforated structure,drilled holes retain their circularity after 21 days of immersion test and distinct corrosion phenomenon occur at localized sites.

Malware Analysis and Classification: A Survey

One of the major and serious threats on the Internet today is malicious software, often referred to as a malware. The malwares being designed by attackers are polymorphic and metamorphic which have the ability to change their code as they propagate. Moreover, the diversity and volume of their variants severely undermine the effectiveness of traditional defenses which typically use signature based techniques and are unable to detect the previously unknown malicious executables. The variants of malware families share typical behavioral patterns reflecting their origin and purpose. The behavioral patterns obtained either statically or dynamically can be exploited to detect and classify unknown malwares into their known families using machine learning techniques. This survey paper provides an overview of techniques for analyzing and classifying the malwares.

Investigation of Tolerable Laser Linewidth for Different Modulation Formats in CO-OFDM Systems

The ideal behavior of communication system requires a single frequency carrier. In optical communication system, light is used as a carrier. Practical laser source has a finite linewidth due to variations in the frequency of operation, hence, resulting in undesired phase perturbations in the signal whereas the ideal requirement is the delta function spectral shape at the carrier frequency. The spectral shape gets broadened due to phase noise and is modeled as lorentzian shape. Linewidth is a measure of stability of laser phase noise with time. Coherent Optical Orthogonal frequency division multiplexing (CO-OFDM) along with the spectrally efficient Quadrature Amplitude Modulation (QAM) formats is emerging as one of the best solutions for future high speed fiber transmission systems. Though the coherent, receivers have advantages in terms of sensitivity and selectivity, laser phase noise is the main limitation of such systems as the laser phase noise further causes common phase rotation of all the subcarriers per symbol and also results in inter carrier interference. QAM formats are also susceptible to laser phase noise. Phase noise in coherent systems is governed by laser linewidth. Hence, it is very important to investigate the impact of laser linewidth in CO-OFDM systems. This paper investigates the tolerable laser linewidths for different QAM formats in a 40 Gbps COOFDM system.

Lactate reloaded–reevaluation of the importance of lactate monitoring in the management of adult sepsis in the emergency department

For about a quarter of a century,monitoring lactate levels and/or lactate clearance has been an unquestionable cornerstone in sepsis management.The elevated lactate level appeared to be an independent predictor of mortality,and the consequent metabolic acidosis was thought to explain a number of pathophysiological changes seen in septic shock.Recent physiological and clinical findings seem to challenge the adverse role of lactic acidosis in sepsis.Evidence suggests that lactate levels are not necessarily directly proportional to either tissue or cellular hypoxia,and conversely,despite high lactate levels,increased peripheral tissue oxygen pressure can be measured in adult patients with septic shock.According to the most recent understanding of in vitro and in vivo evidence,the elevated lactate level in sepsis might be a normal reaction due to adrenergic stress with potential beneficial/protective physiological effects,as well.On the one hand,burning lactic may help fuel the body during critical illness,but on the other hand,with a slight drop in pH,the body may counteract certain deleterious changes during the dysregulated host response;reduce the chances of reperfusion myocardial injury,and improve tissue oxygenation by shifting the haemoglobin dissociation curve to the right.Understanding the pathophysiological process in sepsis resulting in elevated lactate levels may aid management in an emergency,medicine,and intensive care settings.With more in-depth physiological knowledge,physicians may inevitably surpass normalisation heuristics and deliver personalized rather than protocolised sepsis resuscitation.

Cyclic codes of length 2k over Z8

We study the structure of cyclic codes of length 2k?over Z8?for any natural number k.? It is known that cyclic codes of length 2k?over Z8?are ideals of the ring R=Z8[X]/. In this paper we prove that the ring R=Z8[X]/ is a local ring with unique maximal ideal, thereby implying that R is not a principal ideal ring.? We also prove that cyclic codes of length?2k?over Z8?are generated as ideals by at most three elements.

Evaluation and analysis of cutting speed, wire wear ratio, and dimensional deviation of wire electric discharge machining of super alloy Udimet-L605 using support vector machine and grey relational analysis

The current study investigates the behavior of wire electric discharge machining （WEDM） of the super alloy Udimet-L605 by employing sophisticated machine learning approaches. The experimental work was designed on the basis of the Taguchi orthogonal L27 array, consid- ering six explanatory variables and evaluating their influ- ences on the cutting speed, wire wear ratio （WWR）, and dimensional deviation （DD）. A support vector machine （SVM） algorithm using a normalized poly-kernel and a radial-basis flow kernel is recommended for modeling the wire electric discharge machining process. The grey rela- tional analysis （GRA） approach was utilized to obtain the optimal combination of process variables simultaneously, providing the desirable outcome for the cutting speed, WWR, and DD. Scanning electron microscope and energy dispersive X-ray analyses of the samples were performed for the confirmation of the results. An SVM based on the radial-basis kernel model dominated the normalized poly- kernel model. The optimal combination of process vari- ables for a mutually desirable outcome for the cutting speed, WWR, and DD was determined as Ton1, Toffa, Ip1, WT3, SV1, and WF3. The pulse-on time is the significant variable influencing the cutting speed, WWR, and DD. The largest percentage of copper （8.66%） was observed at the highest cutting speed setting 7.05% of copper at the low of the machine compared to cutting speed setting of the machine.

Power quality investigation of a solar PV transformer-less grid-connected system fed DVR

This paper presents a single stage transformerless grid-connected solar photovoltaic （PV） system with an active and reactive power control. In the absence of active input power, the grid-tied voltage source converter （VSC） is operated in a reactive power generation mode, which powers the control circuitry, and maintains a regulated DC voltage to the VSC. A data-based maximum power point tracking （MPPT） control scheme which performs power quality control at a maximum power by reducing the total harmonic distortion （THD） in grid injected current as per IEEE-519/1547 standards is implemented. A proportionalintegral （P1） controller based dynamic voltage restorer （DVR） control scheme is implemented which controls the grid side converter during single-phase to ground fault. The analysis includes the grid current THD along with the corresponding variation of the active and reactive power during the fault condition. The MPPT tracks the actual variable DC link voltage while deriving the maximum power from the solar PV array, and maintains the DC link voltage constant by changing the modulation index of the VSC. Simulation results using Matlab/Simulink are presented to demonstrate the feasibility and validations of the proposed novel MPPT and DVR control systems under different environmental conditions.

THD reduction with reactive power compensation for fuzzy logic DVR based solar PV grid connected system

Dynamic voltage restorer （DVR） is used to protect sensitive loads from voltage disturbances of the distribution generation （DG） system. In this paper, a new control approach for the 200 kW solar photovoltaic grid connected system with perturb and observe maximum power point tracking （MPPT） technique is implemented. Power quality improvement with comparison is conducted during fault with proportional integral （PI） and artificial intelligence-based fuzzy logic controlled DVR. MPPT tracks the actual variable DC link voltage while deriving the maximum power from a photovoltaic array and maintains DC link voltage constant by changing modula- tion index of the converter. Simulation results during fault show that the fuzzy logic based DVR scheme demonstrates simultaneous exchange of active and reactive power with less total harmonic distortion （THD） present in voltage source converter （VSC） current and grid current with fast tracking of optimum operating point at unity power factor. Standards （IEEE-519/1547）, stipulates that the current with THD greater than 5% cannot be injected into the grid by any distributed generation source. Simulation results and validations of MPPT technique and operation of fuzzy logic controlled DVR demonstrate the effectiveness of the proposed control schemes.