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An artificial neural network (ANN) based tunable automated standalone RF sensor system is proposed to realize an improved sensing module involving a quite accurate solution of the non-linear inverse characterization problem. The presented tunable sensor system is quite novel as it alleviates the need for any active tuning circuitry. Moreover, the proposed unified design topology facilitates a relatively higher tuning range (1900 MHz) than that of the earlier reported (580 MHz) capacitor-based tunable complementary split-ring resonator (CSRR). The higher tuning range of structures resulted from the improved design configuration comprising a modified CSRR design coupled with a modified microstrip line. The obtained dielectric sensitivity is ∼8.8%. The numerically generated S-parameters of various dielectric samples are used here as a training dataset for the ANN, which is trained using the Levenberg–Marquardt backpropagation algorithm in combination with the Bayesian regularization. Finally, several standard test samples at different unloaded tuned frequencies are measured to record the corresponding resonant frequency and magnitude of the S-parameter in order to process them using the proposed ANN-based sensor system. It is found that the developed ANN-based sensor system provides a reasonably accurate value of the extracted complex permittivity over the frequency range under consideration, which basically removes the need for designing multiple resonant structures unlikely to the conventional resonant sensors. [ABSTRACT FROM AUTHOR]

An artificial neural network (ANN) based frequency controlled automated RF sensor system for the characterization of dispersive liquids is presented. The frequency of the designed structure is electronically controlled by varying the applied reverse-biased voltage to the complementary split ring resonator (CSRR) attached varactor diode. A hybrid modelling approach has mainly been devised to account for the effects of biasing circuitry and the parasitic elements. The designed RF sensor can provide a relatively higher tuning bandwidth (800 MHz) for applied DC biasing voltage of 0–25 V. The proposed sensor system employs an artificially intelligent feed-forward neural network architecture, which is trained by the Levenberg–Marquardt training algorithm for the complex permittivity estimation in the designated frequency band with reasonable accuracy. It employs the Bayesian Regularization for better input–output correlation and system performance. The ANN based characterization algorithm is integrated with a graphical user interface (GUI) and implemented using MATLAB. [ABSTRACT FROM AUTHOR]

We have examined the reliability risks of complementary SiGe HBTs on thick-film silicon on insulator (SOI). DC stress techniques, such as reverse emitter–base (EB) stress, mixed-mode stress, and flyback measurements, were used to characterize the safe operating area of n-p-n and p-n-p SiGe HBTs fabricated on SOI substrates. The measurements were analyzed based on fundamental damage mechanisms, such as hot carriers generated at the EB and collector–base junctions during large reverse voltage, and thermal runaway as a result of high current phenomena. RF stress (using a large amplitude continuous-wave signal) was also performed to examine the reliability of complementary bipolar complementary metal–oxide–semiconductor devices and circuits in an RF context. In both cases, p-n-p SiGe HBTs were found to be more reliable than n-p-n SiGe HBTs, a fact that may offer opportunities for circuit design optimization. [ABSTRACT FROM PUBLISHER]

In this article, the author discusses a systematic review that revealed the equal effectiveness of resin-based and glass ionomer cement (GIC) fissure sealants in preventing dental carries. The author says that the review has two weaknesses, such as the assumption of tooth pairs' independence and the application of a fixed effects model in heterogeneity determination. The author also mentions that based on the limited evidence, neither resin-based nor GIC fissure sealants are of high quality.

The hot carrier and ionizing radiation responses of 45-nm SOI RF nMOSFETs are investigated. Devices with “tight” source/drain (S/D) contact spacing have improved RF performance but degraded hot carrier reliability and radiation tolerance. Devices with “loose” gate finger-to-gate finger spacing have improved RF performance and also improved hot carrier and radiation tolerance. The effects of finger width on the hot carrier stress and ionizing radiation degradation of strained silicon-on-insulator RF MOSFETs are also investigated. Enhanced degradation is observed for devices with wide finger widths and is attributed to the greater channel-region mechanical stress induced impact ionization. This result is contrary to the previous studies which showed that narrow channel width devices should exhibit greater damage. Taken together, these results have serious consequences for RF circuits that require large widths for sufficient RF gain. Finally, devices with symmetric halo doping are observed to exhibit greater total-dose degradation than devices with asymmetric halo doping. [ABSTRACT FROM PUBLISHER]

Background. The authors evaluated the effectiveness of using a patient simulator (MARC Patient Simulator [MARC PS], BlueLight analytics, Halifax, Nova Scotia, Canada), to instruct dental students (DS) on how to deliver energy optimally to a restoration from a curing light. Five months later, the authors evaluated the retention of the instruction provided to the DS. Methods. Toward the end of the DS' first year of dental education, the authors evaluated the light- curing techniques of one-half of the class of first-year DS (Group 1) before and after receiving instruction by means of the patient simulator. Five months later, they retested DS in Group 1 and tested the remaining first-year DS who were then second-year DS and who had received no instruction by means of the patient simulator (Group 2). They gave DS in Group 1 and Group 2 MARC PS instruction and retested them. The authors also the tested fourth-year DS (Group 3) and dentists (Group 4) by using the MARC PS before giving any instruction by means of the MARC PS. Results. The results of one-way analysis of variance (ANOVA) showed that there were no significant differences in the ability of dentists and DS to light cure a simulated restoration before they received instruction by means of the patient simulator (P = .26). The results of two-way ANOVA and Fisher protected least significant difference tests showed that after receiving instruction by means of the patient simulator, DS delivered significantly more energy to a simulated restoration, and this skill was retained. There were no significant differences between DS in Group 1 and Group 2 after they had received instruction by means of the patient simulator. Conclusions. The abilities of dentists and DS to light cure a simulated restoration were not significantly different. Hands-on teaching using a patient simulator enhanced the ability of DS to use a curing light. This skill was retained for at least five months. Practical Implications. The education provided to dentists and DS is insufficient to teach them how to deliver the optimum amount of energy from a curing light. Better teaching and understanding of the importance of light curing is required. [ABSTRACT FROM AUTHOR]