2,068 research outputs found
Voltage-Mode Highpass, Bandpass, Lowpass and Notch Biquadratic Filters Using Single DDCC
A new voltage-mode multifunction biquadratic filter using one differential difference current conveyor (DDCC), two grounded capacitors and three resistors is presented. The proposed circuit offers the following attractive advantages: realizing highpass, bandpass, lowpass and notch filter functions, simultaneously, from the same circuit configuration; employing grounded capacitors, which is ideal for integration and simpler circuit configuration
DCCII-Based Novel Lossless Grounded Inductance Simulators With No Element Matching Constrains
In 1996, the differential current conveyor (DCCII) was introduced as a versatile active element with current differencing capability. Therefore, in this study, the usefulness of the DCCII is shown on six novel lossless grounded inductance simulator circuits. Proposed circuits simultaneously employ minimum number of elements, i.e. single DCCII, one capacitor, and two resistors. No passive element matching restriction is needed and all solutions are electronically tunable in case that one of resistors is replaced by MOSFET-based voltage-controlled resistor. The internal structure of the active element has been implemented using the TSMC 0.25 um SCN025 CMOS process BSIM3v3.1 parameters. Firstly, the performance of the selected inductor simulator is evaluated and subsequently verified in the design of 5th-order high-pass ladder and 2nd-order frequency filters. In addition, experimental results using commercially available AD844/ADs are given to verify the theoretical analysis and SPICE simulations
High-Order Current-Mode and Transimpedance-Mode Universal Filters with Multiple-Inputs and Two-Outputs Using MOCCIIs
A high-order current-mode and transimpedance-mode universal filter with multiple-inputs and two-outputs based on multiple output second-generation current conveyors (MOCCIIs) is introduced. By choosing the input current terminals appropriately, the current-mode and transimpedance-mode lowpass, bandpass, highpass, notch or allpass filters can be obtained without component matching conditions. The proposed nth order universal filter requires (n+1) MOCCIIs, (n+1) resistors and n grounded capacitors. As examples, the first-order, biquadratic and third-order universal filters are given and compared with previous published works
High Input Impedance Voltage-Mode Universal Biquadratic Filters With Three Inputs Using Three CCs and Grounding Capacitors
Two current conveyors (CCs) based high input impedance voltage-mode universal biquadratic filters each with three input terminals and one output terminal are presented. The first circuit is composed of three differential voltage current conveyors (DVCCs), two grounded capacitors and four resistors. The second circuit is composed of two DVCCs, one differential difference current conveyor (DDCC), two grounded capacitors and four grounded resistors. The proposed circuits can realize all the standard filter functions, namely, lowpass, bandpass, highpass, notch and allpass filters by the selections of different input voltage terminals. The proposed circuits offer the features of high input impedance, using only grounded capacitors and low active and passive sensitivities. Moreover, the x ports of the DVCCs (or DDCC) in the proposed circuits are connected directly to resistors. This design offers the feature of a direct incorporation of the parasitic resistance at the x terminal of the DVCC (DDCC), Rx, as a part of the main resistance
Electronically Tunable Third-Order Quadrature Oscillator Using CDTAs
A current/voltage-mode third-order quadrature oscillator based on current differencing transconductance amplifiers (CDTAs) is presented in this paper. Outputs of two current-mode and two voltage-mode sinusoids each with 90o phase difference are available in the quadrature oscillator circuit. The oscillation condition and oscillation frequency are independently controllable. The proposed circuit employs only grounded capacitors and is ideal for integration. Simulation results are included to confirm the theoretical analysis
Web Courseware Usability and Tools for the Enhancement of Teacher Education
This article presents the findings of a study designed to investigate the effectiveness of the usability and tools in on-line course management packages. It also describes the challenges that teacher educators may face with respect to student use of on-line courses. Five research questions were formulated to ·explore the usability issues and the use of teaching tools in the on-line courseware, WebCT. The findings indicated that there was a significant difference between students\u27 acceptance of on-line courseware, WebCT, based on their genders: female students were more satisfied than male students. Significant variance among academic status (Freshman, Sophomore, Junior, Senior, and Graduate) was observed in students\u27 acceptance ofWebCT, demonstrating that graduate students were more likely to prefer learning on-line than undergraduates. Two usability elements, perceptual limitation and learnability, were the most statistically significant predictors in the on-line courseware. No significant differences were observed among students\u27 acceptance of WebCT in terms of their previous on-line experiences and computer skills. In addition, the qualitative results provided compelling evidence that learners did not use the Help tools as their primary aid when encountering difficulties. Some problems associated with the use of the discussion board, such as sending/ viewing attachments, were revealed in the discussion section
Prediction of Nontrivial Band Topology and Superconductivity in MgPb
The interplay of BCS superconductivity and nontrivial band topology is
expected to give rise to opportunities for creating topological
superconductors, achieved through pairing spin-filtered boundary modes via
superconducting proximity effects. The thus-engineered topological
superconductivity can, for example, facilitate the search for Majorana fermion
quasiparticles in condensed matter systems. Here we report a first-principles
study of MgPb and predict that it should be a superconducting topological
material. The band topology of MgPb is identical to that of the archetypal
quantum spin Hall insulator HgTe, while isostructural and isoelectronic
MgSn is topologically trivial; a trivial to topological transition is
predicted for MgSnPb for x~0.77. We propose that
MgPb-MgSn quantum wells should generate robust spin-filtered edge
currents in analogy to HgTe/CdTe quantum wells. In addition, our calculations
predict that MgPb should become superconducting upon electron doping.
Therefore, MgPb is expected to provide a practical material platform for
studying emergent phenomena arising from the interplay of superconductivity and
band topology.Comment: 5 figure
REVAMP: Automated Simulations of Adversarial Attacks on Arbitrary Objects in Realistic Scenes
Deep Learning models, such as those used in an autonomous vehicle are
vulnerable to adversarial attacks where an attacker could place an adversarial
object in the environment, leading to mis-classification. Generating these
adversarial objects in the digital space has been extensively studied, however
successfully transferring these attacks from the digital realm to the physical
realm has proven challenging when controlling for real-world environmental
factors. In response to these limitations, we introduce REVAMP, an easy-to-use
Python library that is the first-of-its-kind tool for creating attack scenarios
with arbitrary objects and simulating realistic environmental factors,
lighting, reflection, and refraction. REVAMP enables researchers and
practitioners to swiftly explore various scenarios within the digital realm by
offering a wide range of configurable options for designing experiments and
using differentiable rendering to reproduce physically plausible adversarial
objects. We will demonstrate and invite the audience to try REVAMP to produce
an adversarial texture on a chosen object while having control over various
scene parameters. The audience will choose a scene, an object to attack, the
desired attack class, and the number of camera positions to use. Then, in real
time, we show how this altered texture causes the chosen object to be
mis-classified, showcasing the potential of REVAMP in real-world scenarios.
REVAMP is open-source and available at https://github.com/poloclub/revamp
Detection of Ubiquitination on Syk and Documenting Syk Stability
Post-translational modifications regulate the activities of proteins important to numerous diseases. Spleen Tyrosine Kinase (Syk) is particularly interesting to researchers because it modifies many targets and plays multiple roles in regulating cells in our bodies and its abnormal modifications may contribute to cancer, Alzheimer’s disease and allergies. In an attempt to study these modifications of Syk, we first looked at detecting ubiquitination on Syk protein. Ubiquitin, a small 8 kDa molecule, attaches to lysine residues on protein. The attachment of ubiquitin to Syk may cause Syk to either propagate signals onwards to activate other proteins or signal it to undergo proteasomal degradation. To detect ubiquitination of Syk, B cell lymphoma DG75 with endogenous Syk expression was electroporated with HA-tagged Ubiquitin expression vector to introduce the ubiquitin molecule into the cells. Immunoprecipitation of Syk was performed to isolate the total Syk and to visualize the ubiquitination by Western Blot with anti-HA antibody. When cells were treated with Cyclohexamide (CHX), a protein translation inhibitor, we did not observe significant decrease of Syk in protein level, indicating that Syk is an exceptionally stable protein with a half-life longer than 72 hours. Upon treatment of cells with both CHX and MG132, a proteasome inhibitor, we reproducibly observed a detectable accumulation of Syk protein in 24 hours. The established technique will not only facilitate the study of the impact of ubiquitination on Syk in signal transduction, it also will lead us to identify the potential significance of ubiquinated lysine residues on Syk in cellular function
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