Fatigue fracture surface analysis in C45 steel specimens using X-Ray fractography

X-Ray fractography is a useful technique to analyse the mechanisms operating in fracture and involves an examination of the fracture surface. In the present investigation, this technique has been employed to study the fatigue fracture behaviour of a medium carbon steel of C45 grade in different heat treated conditions. The different trends observed in the residual stress (σr) and diffraction profile full width at half maximum intensity (B) relationships with the maximum stress intensity factor (Kmax) on the fracture surface have been correlated to the differences in flow characteristics of these materials. The root mean square value of microstrain , and the coherent domain (particle) size, D, were determined through single line diffraction profile (Voigt's) analysis. It has been observed that contribution of microstrain to profile broadening is more significant than that due to domain size. However, at higher Kmax values an influence of D was found on line broadening, to a small extent. Results of sub-surface stress measurements were compared in two conditions. A good correlation was noticed between the depths below the fracture surface, designated as ymax, at which the measured σr, reaches the base material value and the corresponding monotonic plastic zone size (rp) obtained by calculation. The observed depths below the fracture surface (ypeak) at which an increase in σr or a decrease in B was noticed, appear to be related to the conditions of the near-tip regions where the material has undergone severe fatigue damage and cyclic softening

Effect of the intermediate quenching on fracture toughness of ferrite-martensite dual phase steels

The main aim of the research work is to examine the fracture toughness of the dual phase steels prepared using the intermediate quenching method. The ferrite-martensite dual phase (DP) steel is produced using low carbon micro alloyed steel by the heat treatment and intercritical quenching technique using various intercritical temperatures such as 740,760,780,800 and 820oC. The samples of the produced dual phase steel are analyzed for their microstructure using optical microscope. The fracture toughness investigations for the dual phase steel have been carried out using ASTM standard testing procedure. From the results it is observed that the fine distribution and equal volume fraction of ferrite and martensite phases at 780oC. The effect of which, the A780 steel has demonstrated excellent fracture toughness which is the result of intermediate quenching technique. The fractography analysis it is clear that the ductile initiated brittle fracture is occurred which is due to the increased hard martensite phase and the increment in the stress accumulation at the ferrite which also leads to the higher elongation

Comparison of one and two time constant models for lithium ion battery

The fast and accurate modeling topologies are very much essential for power train electrification. The importance of thermal effect is very important in any electrochemical systems and must be considered in battery models because temperature factor has highest importance in transport phenomena and chemical kinetics. The dynamic performance of the lithium ion battery is discussed here and a suitable electrical equivalent circuit is developed to study its response for sudden changes in the output. An effective lithium cell simulation model with thermal dependence is presented in this paper. One series resistor, one voltage source and a single RC block form the proposed equivalent circuit model. The 1 RC and 2 RC Lithium ion battery models are commonly used in the literature are studied and compared. The simulation of Lithium-ion battery 1RC and 2 RC Models are performed by using Matlab/Simulink Software. The simulation results in his paper shows that Lithium-ion battery 1 RC model has more maximum output error of 0.42% than 2 RC Lithium-ion battery model in constant current condition and the maximum output error of 1 RC Lithium-ion battery model is 0.18% more than 2 RC Lithium-ion battery model in UDDS Cycle condition. The simulation results also show that in both simple and complex discharging modes, the error in output is much improved in 2 RC lithium ion battery model when compared to 1 RC Lithium-ion battery model. Thus the paper shows for general applications like in portable electronic design like laptops, Lithium-ion battery 1 RC model is the preferred choice and for automotive and space design applications, Lithium-ion 2 RC model is the preferred choice. In this paper, these simulation results for 1 RC and 2 RC Lithium-ion battery models will be very much useful in the application of practical Lithium-ion battery management systems for electric vehicle applications

Some studies on the influence of stress ratio and test temperature on X-ray fractography observations in C45 steel specimens

This paper deals with additional ¿X-ray fractography¿ observations made on C45 steel, subsequent to the earlier work [K. Rajanna, B. Pathiraj and B. H. Kolster, Fatigue fracture surface analysis in C45 steel specimens using X-ray fractography. Engng Fracture Mech. 39, 147¿157 (1991)]. Fatigue crack: growth tests were carried out at 20°C on CT samples prepared from this steel using different stress ratios (0.1R, 0.5R and 0.7R). Tests were also carried out at different temperatures (¿20°C, 20°C and 115°C) using a stress ratio of 0.1. The fractured surfaces were analysed for their residual stress state. The influence of the test conditions on the residual stresses developed is discussed

MIMO-OFDM BASED COGNITIVE RADIO SYSTEMS WITH IMPERFECT SPECTRUM SENSING BY MULTI-OBJECTIVE OPTIMIZATION TECHNIQUE

This paper presents optimization strategies for a MIMO (Multiple Input Multiple Output) OFDM (Orthogonal Frequency Division Multiplexing) based cognitive radio (CR) system. The proposed optimization  schemes maximize the downlink transmission rate of the CR users under spatial interference constraints, considering both the availability and absence of the primary user (PU) Channel State Information (CSI). A multi-objective optimization (MOOP) approach to investigate the optimal link adaptation problem of MIMO OFDM based cognitive radio (CR) systems, where secondary users (SUs) can opportunistically access the spectrum of primary users (PUs). For such a scenario, we solve the problem of jointly maximizing the CR system throughput and minimizing it’s transmitting power, subject to constraints on both SU and PUs. The optimization problem imposes predefined interference thresholds for the PUs, guarantees the SU quality of service in terms of a maximum bit-error-rate (BER). Additionally, the results show that the performance of the proposed algorithm approaches that of an exhaustive search for the discrete optimal allocations with a significantly reduced computational effort. Simulation results presented validate the performance of the proposed schemes

Intra- and Interspecies Genomic Transfer of the Enterococcus faecalis Pathogenicity Island

Enterococci are the third leading cause of hospital associated infections and have gained increased importance due to their fast adaptation to the clinical environment by acquisition of antibiotic resistance and pathogenicity traits. Enterococcus faecalis harbours a pathogenicity island (PAI) of 153 kb containing several virulence factors including the enterococcal surface protein (esp). Until now only internal fragments of the PAI or larger chromosomal regions containing it have been transfered. Here we demonstrate precise excision, circularization and horizontal transfer of the entire PAI element from the chromosome of E. faecalis strain UW3114. This PAI (ca. 200 kb) contained some deletions and insertions as compared to the PAI of the reference strain MMH594, transferred precisely and integrated site-specifically into the chromosome of E. faecalis (intergenic region) and Enterococcus faecium (tRNAlys). The internal PAI structure was maintained after transfer. We assessed phenotypic changes accompanying acquisition of the PAI and expression of some of its determinants. The esp gene is expressed on the surface of donor and both transconjugants. Biofilm formation and cytolytic activity were enhanced in E. faecalis transconjugants after acquisition of the PAI. No differences in pathogenicity of E. faecalis were detected using a mouse bacteraemia and a mouse peritonitis models (tail vein and intraperitoneal injection). A 66 kb conjugative pheromone-responsive plasmid encoding erm(B) (pLG2) that was transferred in parallel with the PAI was sequenced. pLG2 is a pheromone responsive plasmid that probably promotes the PAI horizontal transfer, encodes antibiotic resistance features and contains complete replication and conjugation modules of enterococcal origin in a mosaic-like composition. The E. faecalis PAI can undergo precise intra- and interspecies transfer probably with the help of conjugative elements like conjugative resistance plasmids, supporting the role of horizontal gene transfer and antibiotic selective pressure in the successful establishment of certain enterococci as nosocomial pathogens

Sensor-based precision nutrient and irrigation management enhances the physiological performance, water productivity, and yield of soybean under system of crop intensification

Sensor-based decision tools provide a quick assessment of nutritional and physiological health status of crop, thereby enhancing the crop productivity. Therefore, a 2-year field study was undertaken with precision nutrient and irrigation management under system of crop intensification (SCI) to understand the applicability of sensor-based decision tools in improving the physiological performance, water productivity, and seed yield of soybean crop. The experiment consisted of three irrigation regimes [I1: standard flood irrigation at 50% depletion of available soil moisture (DASM) (FI), I2: sprinkler irrigation at 80% ETC (crop evapo-transpiration) (Spr 80% ETC), and I3: sprinkler irrigation at 60% ETC (Spr 60% ETC)] assigned in main plots, with five precision nutrient management (PNM) practices{PNM1-[SCI protocol], PNM2-[RDF, recommended dose of fertilizer: basal dose incorporated (50% N, full dose of P and K)], PNM3-[RDF: basal dose point placement (BDP) (50% N, full dose of P and K)], PNM4-[75% RDF: BDP (50% N, full dose of P and K)] and PNM5-[50% RDF: BDP (50% N, full P and K)]} assigned in sub-plots using a split-plot design with three replications. The remaining 50% N was top-dressed through SPAD assistance for all the PNM practices. Results showed that the adoption of Spr 80% ETC resulted in an increment of 25.6%, 17.6%, 35.4%, and 17.5% in net-photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO2 concentration (Ci), respectively, over FI. Among PNM plots, adoption of PNM3 resulted in a significant (p=0.05) improvement in photosynthetic characters like Pn (15.69 µ mol CO2 m−2 s−1), Tr (7.03 m mol H2O m−2 s−1), Gs (0.175 µmol CO2 mol−1 year−1), and Ci (271.7 mol H2O m2 s−1). Enhancement in SPAD (27% and 30%) and normalized difference vegetation index (NDVI) (42% and 52%) values were observed with nitrogen (N) top dressing through SPAD-guided nutrient management, helped enhance crop growth indices, coupled with better dry matter partitioning and interception of sunlight. Canopy temperature depression (CTD) in soybean reduced by 3.09–4.66°C due to adoption of sprinkler irrigation. Likewise, Spr 60% ETc recorded highest irrigation water productivity (1.08 kg ha−1 m−3). However, economic water productivity (27.5 INR ha−1 m−3) and water-use efficiency (7.6 kg ha−1 mm−1 day−1) of soybean got enhanced under Spr 80% ETc over conventional cultivation. Multiple correlation and PCA showed a positive correlation between physiological, growth, and yield parameters of soybean. Concurrently, the adoption of Spr 80% ETC with PNM3 recorded significantly higher grain yield (2.63 t ha−1) and biological yield (8.37 t ha−1) over other combinations. Thus, the performance of SCI protocols under sprinkler irrigation was found to be superior over conventional practices. Hence, integrating SCI with sensor-based precision nutrient and irrigation management could be a viable option for enhancing the crop productivity and enhance the resource-use efficiency in soybean under similar agro-ecological regions

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

PLC Communication using OOK/ASK Modulation for Automatic Meter Reading Systems for Smart Metering in Rural Smart Micro-Grids

Smart Grids are in performance an essential role in the current world. The current research efforts on these smart grids involve the advance in the turf of Smart Metering. The most costly, modest and straightforward to feast out abilities lie in Power Line Communications (PLC), which manufactured them useful in electric grids. Smart Metering in smart grid uses PLC technology in various architectures of LV grid. This paper proposes a scheme for a Smart Metering network with PLC expertise consuming on-off keying/amplitude-shift keying (OOK/ASK'S) Modulation. PLC with AMR schemes hand-me-down in energy conveyance system and recording, usages of illicit electricity by sleuthing because of the current network. More particularly in rural areas, the PLC with AMR Systems can minimize theft and illegal use electricity, which raises the power distribution authorities' revenue. Dissolute and Consistent meter analysis gathering with minor mistakes can be accomplished AMR Systems, which removes the requirement of physically construing meters. The anticipated system for current meters has remained in MATLAB/Simulink software