DCTracVis: a system retrieving and visualizing traceability links between source code and documentation

It is well recognized that traceability links between software artifacts provide crucial support in comprehension, efficient development, and effective management of a software system. However, automated traceability systems to date have been faced with two major open research challenges: how to extract traceability links with both high precision and high recall, and how to efficiently visualize links for complex systems because of scalability and visual clutter issues. To overcome the two challenges, we designed and developed a traceability system, DCTracVis. This system employs an approach that combines three supporting techniques, regular expressions, key phrases, and clustering, with information retrieval (IR) models to improve the performance of automated traceability recovery between documents and source code. This combination approach takes advantage of the strengths of the three techniques to ameliorate limitations of IR models. Our experimental results show that our approach improves the performance of IR models, increases the precision of retrieved links, and recovers more correct links than IR alone. After having retrieved high-quality traceability links, DCTracVis then utilizes a new approach that combines treemap and hierarchical tree techniques to reduce visual clutter and to allow the visualization of the global structure of traces and a detailed overview of each trace, while still being highly scalable and interactive. Usability evaluation results show that our approach can effectively and efficiently help software developers comprehend, browse, and maintain large numbers of links.     

A self-duty-cycled 7.2–8.5 GHz IR-UWB receiver for low power and low data rate applications

A self-duty-cycled non-coherent impulse radio-ultra wideband receiver targeted at low-power and low-data-rate applications is presented. The receiver is implemented in a 130 nm CMOS technology and works in the 7.2–8.5 GHz UWB band, which covers the IEEE 802.15.4a and 802.15.6 mandatories high-band channels. The receiver architecture is based on a non-coherent RF front-end (high gain LNA and pulse detector) followed by a synchronizer block (clock and data recovery or CDR function and window generation block), which enables to shut down the power-hungry LNA between pulses to strongly reduce the receiver power consumption. The main functions of the receiver, i.e. the RF front-end and the CDR block, were measured stand-alone. A maximum gain of 40 dB at 7.2 GHz is measured for the LNA. The RF front-end achieves a very low turn-on time (<1 ns) and an average sensitivity of ?92 dBm for a 10^?3 BER at a 1 Mbps data rate. A root-mean-square (RMS) jitter of 7.9 ns is measured for the CDR for a power consumption of 54 µW. Simulation results of the fully integrated self-duty-cycled 7.2–8.5 GHz IR-UWB receiver (that includes the measured main functions) confirm the expected performances. The synchronizer block consumes only 125 µW and the power consumption of the whole receiver is 1.8 mW for a 3% power duty-cycle (on-window of 30 ns).     

The interfacial transfer of aluminium to steels and ceramic materials under loaded contact at high temperatures II: Both surfaces at high temperatures

The rolling contact between aluminium strips and rolls of different materials, in which the rolls were heated in situ with an auxiliary furnace to a temperature similar to that of the strips, was studied. Rolls of solid alumina failed during the rolling of the aluminium strip; all the other rolls, including plasma spray-coated rolls, remained undamaged. Examination of the structure and composition of the coatings which developed on the rolls showed that there was more transfer for all the different rolls but that the variations between the rolls were much less than they were when the rolls were at ambient temperatures. The thick coatings formed on the rolls were predominantly aluminium metal and the characteristic structure was independent of the original roll surface structures.     

Infrared fluorescence imaging of infarcted hearts with Ag2S nanodots

Ag₂S nanodots have already been demonstrated as promising near-infrared (NIR-II, 1.0–1.45 μm) emitting nanoprobes with low toxicity, high penetration and high resolution for in vivo imaging of, for example, tumors and vasculature. In this work, we have systematically investigated the potential application of functionalized Ag₂S nanodots for accurate imaging of damaged myocardium tissues after a myocardial infarction induced by either partial or global ischemia. Ag₂S nanodots surface-functionalized with the angiotensin II peptide (ATII) have shown over 10-fold enhanced binding efficiency to damaged tissues than non-specifically (PEG) functionalized Ag₂S nanodots due to their interaction with the upregulated angiotensin II receptor type I (AT1R). It is demonstrated how the NIR-II images generated by ATII-functionalized Ag₂S nanodots contain valuable information about the location and extension of damaged tissue in the myocardium allowing for a proper identification of the occluded artery as well as an indirect evaluation of the damage level. The potential application of Ag₂S nanodots in the near future for in vivo imaging of myocardial infarction was also corroborated by performing proof of concept whole body imaging experiments.

     

An inverse procedure for determination of material constants of a periodic multilayer using Floquet wave homogenization

An inverse numerical method for periodic composite characterization is reported. The method utilizes the velocity data based on Floquet wave homogenization. The optimization procedure is performed on the basis of the gradient method. An efficient polynomial function is derived from Christoffel equation. The numerical procedure leads to an analytical form of the minimized function which is related to the whole Floquet data. The set of input data is collected from different azimuthal plane orientations inside the homogenization domain. The output results mainly include the effective elastic constants of the multidirectional composite and the reliability factor. The initialization of the elastic stiffness matrix is obtained by averaging the rigidity tensor corresponding to each layer orientation. This procedure is examined for [0/90] and [0/60/−60] composites; some of the obtained elastic constants are significantly dependent on the frequency. The agreement between the adopted Floquet velocities and the calculated ones is good; the reliability factor does not exceed 1%. Slight deviations are pointed out in the vicinity of the homogenization limits.     

Study of the effect of magnesium concentration on the deposit of allotropic forms of calcium carbonate and related carbon steel interface behavior

Different allotropic forms of calcium carbonate scales were electrochemically deposited on a carbon steel surface in artificial underground Tunisian water at −0.95 V_SCE and various Mg²⁺ concentrations. Because of the importance of the diffusion process, the rotating disk electrode was used. The deposition kinetics were analyzed by chronoamperometry measurements and the calcareous layers were characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The physical model proposed by Gabrielli was used to analyze the EIS measurements. Independent of the deposited allotropic form of calcium carbonate, the measurements showed that the oxygen reduction occurs in the pores formed between the CaCO₃ crystals and the metallic surface.     

Engineering electrospun nanofibrillar surfaces for spinal cord repair: a discussion

BACKGROUND: The design of implants comprised of biodegradable electrospun nanofibers for the purpose of bridging injuries in damaged spinal cord is discussed. Electrospun nanofibers structurally mimic the extracellular matrix on which neurons and other cell types grow in vivo. This property has created great interest for their use in tissue engineering applications. However, their employment as biomimetic surfaces for such in vivo applications is still in its infancy. RESULTS: A nonwoven fabric comprised of electrospun polyamide nanofibers supported modest axonal regeneration in injured adult rat spinal cord. Covalent modification of the nanofibers with a bioactive peptide derived from the neuroregulatory extracellular matrix molecule tenascin‐C enhanced the ability of the nanofibers to facilitate axonal regrowth. However, the random orientation of the nanofibrillar fabric folds was an impediment to the forward movement of axons. CONCLUSIONS: Polyamide nanofibers covalently modified with neuroactive molecules provide a promising material for grafts to promote spinal cord regeneration. However, for the proper guidance of regrowing axons, attention must be paid to the engineering of ordered nanofibrillar structures. Copyright © 2007 Society of Chemical Industry     

Adaptive MRAC-based direct torque control with SVM for sensorless induction motor using adaptive observer

This paper presents an improved direct torque control (DTC) method for induction motor (IM) drive. The main drawback of the conventional DTC is the use of hysteresis comparators which leads to high torque and flux ripples. The improvement in this paper includes using the space vector modulation to preserve a constant switching frequency and to reduce totally flux and torque ripples. Besides, the torque and stator flux regulation will be done based on model reference adaptive control (MRAC) strategy to ensure a robust control against external disturbance and less sensitivity from machine parameter variation unlike the conventional proportional-integral (PI) controllers. Furthermore, a design of an adaptive observer based on Lyapunov stability is presented for speed/flux and load torque estimation. The observer can improve the control performances and decrease the cost and increase reliability of the global control system by reducing the number of sensors. The proposed strategy will be examined under simulation tests using Matlab/Simulink and experimental implementation with real-time interface (RTI) based on dSpace 1104 board.