Thermoelastoplastic and Residual Stress Analysis during Induction Hardening of Steel

A theoretical model was developed to predict the thermoelastoplastic and residual stresses developed in a round steel bar during induction hardening. For numerical analysis, a quasi- static, uncoupled thermoelastoplastic solution based on the hyperbolic sine law of Tien and Richmond was formulated. The properties of the material were assumed to be temperature dependent. The phase transformation was considered in the numerical calculation, and the results were compared with the case where phase transformation is avoided. The cylinder was heated rapidly; once the temperature of the outer surface exceeded the transformation temperature, the cylinder was rapidly cooled. Accordingly, in the numerical calculation, only the area at the vicinity of the outer surface was assumed to transform to martensite. The results showed that the compressive residual stresses at the vicinity of the outer surface were considerably higher than the tensile stresses at the center.     

Experimental and numerical investigations of low velocity impact behavior of high-performance fiber-reinforced cement based composite

Fiber-reinforced concrete (FRC) has been used in structural applications in order to enhance the structural performance under dynamic loading and reduce cracking and spalling phenomena by increasing toughness, ductility, and tensile strength of the concrete. High-performance fiber-reinforced cement based composite (HPFRC) is a high-strength FRC with enhanced high-performance characteristics. Recent studies have shown that HPFRC has higher impact resistance than other types of concrete. Therefore, it has been widely considered as a promising material for the construction of important and strategic structures. HPFRC panels are tested by drop projectiles up to an impact at which failure occurs. Mechanical properties of HPFRC are obtained to define material parameters in the MAT_SOIL_CONCRETE model in LS-DYNA, which is used to simulate the behavior of HPFRC panel under impact loading and perform parametric studies. Predicted crack and failure patterns on both sides of the HPFRC panel based on finite element simulation are in good agreement with their corresponding experimental results.     

Multi‐threshold and multi‐input DNA logic design style for profiling the microRNA biomarkers of real cancers

Early detection of cancer is very critical because it can reduce the treatment risk and cost. MicroRNAs (miRNAs) have been introduced in recent years as an efficient class of biomarkers for cancer early detection. Now, real‐time polymerase chain reaction has been used to profile the miRNA expression, which is costly, time consuming and low accuracy. Most recently, DNA logic gates are used to detect the miRNA expression level that is more accurate and faster than previous methods. The DNA‐based logic gates face with serious challenges such as the large complexity and low scalability. In this study, the authors proposed a methodology to design multi‐threshold and multi‐input DNA‐based logic gates in response to specific miRNA inputs in live mammalian cells. The proposed design style can simultaneously recognise multiple miRNAs with different rising and falling thresholds. The design style has been evaluated on the lung cancer biomarkers and the experimental results show the efficiency of the proposed method in terms of accuracy, efficiency and speed.Inspec keywords: DNA, logic design, biocomputing, RNA, molecular biophysics, logic gates, lung, genetics, cellular biophysics, cancer, biology computing, enzymes, biosensorsOther keywords: falling thresholds, specific miRNA inputs, multiinput DNA‐based logic gates, low scalability, DNA‐based logic gates face, miRNA expression level, DNA logic gates, low accuracy, time consuming, real‐time polymerase chain reaction, cancer early detection, treatment risk, cancers, microRNA biomarkers, multiinput DNA logic design style, multithreshold, lung cancer biomarkers     

Internet routing instability

This paper examines the network interdomain routing information exchanged between backbone service providers at the major US public Internet exchange points. Internet routing instability, or the rapid fluctuation of network reachability information, is an important problem currently facing the Internet engineering community. High levels of network instability can lead to packet loss, increased network latency and time to convergence. At the extreme, high levels of routing instability have led to the loss of internal connectivity in wide-area, national networks. We describe several unexpected trends in routing instability, and examine a number of anomalies and pathologies observed in the exchange of inter-domain routing information. The analysis in this paper is based on data collected from border gateway protocol (BGP) routing messages generated by border routers at five of the Internet core's public exchange points during a nine month period. We show that the volume of these routing updates is several orders of magnitude more than expected and that the majority of this routing information is redundant, or pathological. Furthermore, our analysis reveals several unexpected trends and ill-behaved systematic properties in Internet routing. We finally posit a number of explanations for these anomalies and evaluate their potential impact on the Internet infrastructure     

RNA secondary structured logic gates for profiling the microRNA cancer biomarkers

Deregulation of microRNAs expression is symptomatic of cancer disease and occurs before the awareness of cancer signs. Early detection of cancer disease can improve or drop the disease entirely. DNA computing is an emerging field of detecting microRNAs based on toehold‐mediated strand displacement reactions, which is a more efficient method than the commonly used method like real‐time PCR. Accuracy and cost of diagnostic applications are essential criteria that are achieved by using the DNA logic gates based on the DNA computing method. In this study, the authors proposed the multi‐input liver cancer biosensor with the RNA secondary structure motifs as the computational module and two approaches are suggested.Inspec keywords: cancer, biocomputing, biochemistry, DNA, RNA, biosensors, logic gates, liver, macromolecules, genetics, molecular biophysics, diseasesOther keywords: RNA secondary structured logic gates, microRNA cancer biomarkers, microRNAs expression, cancer disease, cancer signs, detecting microRNAs, toehold‐mediated strand displacement reactions, DNA logic gates, DNA computing method, multiinput liver cancer biosensor, RNA secondary structure motifs     

A Multiband Inductor-Reuse CMOS Low-Noise Amplifier

This paper presents the design and implementation of a new multiband, multistandard CMOS low-noise amplifier (LNA) that reuses inductors for different frequency bands to minimize chip area. The idea is to adaptively reconfigure a CMOS transistor in either common source or common gate configuration to achieve narrow-band (NB) or wide-band (WB) input matching, respectively, while conveniently reusing input and load inductors for both bands. This architecture is suitable for 802.11 a/b/g and Public Safety Broadband (PSB) applications, where the NB configuration covers wireless local area network (WLAN) 802.11 b/g, while the WB configuration accommodates the PSB at 4.9 GHz and WLAN 802.11 a. Two versions of the proposed idea, a tapped-capacitor and a tapped-inductor input-matched LNA, have each been designed and fabricated in 0.13-mum CMOS and measurement results are demonstrated.     

Motivating mechanical engineers to minor in electrical engineering

The objective of this paper is to describe an innovative teaching technique consisting of pedagogy and motivation as instruments to gradually enhance the interest of mechanical engineering students for minoring in electrical engineering. A study was conducted comparing the performance of 87 students in four classes majoring in mechanical engineering at Temple University, USA. Confidentially conducted student surveys were statistically analyzed. In conclusion, the number of students opting to take up a minor in electrical engineering gradually increased from 0 to 36% reflecting the gradual increase in electrical engineering content, through an emphasis on pedagogical strategy and the motivation provided     

On reducing the post-heat-treatment time of the weldment

Post heat treatment of weldments is one of the most extensively used techniques by the industrial community for relieving welding residual stresses. Such practice not only delays the manufacturing process, but also increases the cost of manufacturing. In this article, an idea of a new welding technique, which is a promising tool for relieving welding residual stresses, is presented. This method is anticipated to reduce the time and cost of the manufacturing process. The first part of the investigation focuses on simulation of an idea by using an auxiliary heat source for creating a weldment with a more uniform temperature distribution both spatially and temporally. A subroutine has been developed for optimizing the size of an auxiliary heat input (AHI). The details of the subroutine and the parameters considered for optimizing the AHI are presented. The results show that by increasing the stabilizing temperature and size of the AHI, the speed of cooling and spatial temperature gradient decreases. This may result in reducing the level of residual stresses.     

The Blaster Worm: Then and Now

In August of 2003 the Blaster worm struck the Internet, infecting at least 100,000 Microsoft Windows systems and causing millions of dollars in damages. In spite of considerable cleanup efforts, an antiworm aimed at patching systems, and a widely downloaded clean-up tool from Microsoft, the worm is still very much alive. In this article we describe observations of the Blaster worm from its onset in 2003 to its continued persistence a year later.