Logarithmic Mode Research Articles

Reduced-Order Sliding Mode Observer-Based Backstepping Integral Logarithmic Sliding Mode Control: Application to Wing Aeroelastic System

Reduced-Order Sliding Mode Observer-Based Backstepping Integral Logarithmic Sliding Mode Control: Application to Wing Aeroelastic System

Uniformly Loaded Logarithmic Beam Mode with Spatially Varying Flexural Rigidity

AbstractThis analysis explores natural leading modes represented by logarithmic functions, achieved by imposing four boundary constraints at the ends of an elastic inhomogeneous beam. The beam possessing constant material inertia, is assumed to be uniformly loaded, and is composed of material with variable stiffness. It is sought analytical expressions for beam deflections in terms of logarithmic functions. Our findings demonstrate that such formulae can be derived for a beam under axially uniform load and with spatially distributed flexural rigidity. Subsequently, the beam shapes and material properties for four specific scenarios are identified: free-free logarithmic beam, cantilevered logarithmic beam, simply-supported logarithmic beam, and simply-supported sliding logarithmic beam. Explicit logarithmic beam responses, governed by a limited number of shape parameters, are illustrated graphically using normalized deflections with respect to the maximum deflection. Highly deflected elastic logarithmic modes emerge as a consequence of high flexural rigidity influenced by the uniformly applied transverse load. These elucidated logarithmic beam modes offer potential practical applications in the structural design of functionally graded materials. They also serve as valuable testing platforms for numerical techniques employed in the analysis of more complex beam problems.

Human-Assisted Regulation of the Deployment of a Tethered Space Robot via Feasibility Condition Optimization and Fast Logarithmic Sliding Mode

Human-Assisted Regulation of the Deployment of a Tethered Space Robot via Feasibility Condition Optimization and Fast Logarithmic Sliding Mode

Dynamic Event-Triggered and Fast Natural Logarithmic Sliding Mode Path Tracking Control for Unmanned Ground Vehicles With the Experiment Validation

Dynamic Event-Triggered and Fast Natural Logarithmic Sliding Mode Path Tracking Control for Unmanned Ground Vehicles With the Experiment Validation

Application of variational mode decomposition–based Hilbert marginal differential cepstrum for hydrocarbon detection

AbstractThe possibilities offered by the use of variational mode decomposition–based Hilbert marginal spectrum and the differential cepstrum for gas‐bearing detection are studied in this paper. We propose a novel variational mode decomposition–based Hilbert marginal differential cepstrum for hydrocarbon detection. Variational mode decomposition–based Hilbert marginal spectrum is first computed. Then discrete cosine transform is carried out to the differential logarithmic variational mode decomposition–based Hilbert marginal spectrum to obtain the variational mode decomposition–based Hilbert marginal differential cepstrum. For hydrocarbon detection, the seismic amplitude anomaly section is generated by extracting the first and second common quefrency sections. Compared with the traditional Fourier‐based cepstrum, the wavelet‐based cepstrum and the Berthil cepstrum, it has the ability to effectively reveal more detailed frequency‐dependent amplitude anomalies with high accuracy and resolution. Model tests and field data applications from a carbonate reservoir in China show that the variational mode decomposition‐based Hilbert marginal differential cepstrum can provide a better gas‐prone interpretation. The proposed method can be a complementary approach to current cepstrum‐based hydrocarbon detection methods and the spectrum decomposition methods.

Floating Source/Drain Enabled Linear–Linear–Logarithmic Self-Adaptive One-Transistor Active Pixel Sensor

In this work, a novel one-transistor active pixel sensor (1T-APS) with adjustable self-adaptive sensitivity enabled by floating source/drain (S/D) is demonstrated on 22-nm fully depleted Si-on-insulator (FD-SOI) platform. Additional control gates (CGs) with floating S/Ds are incorporated into the sensor, which are parallel to the sensing gate (SG). For weak illumination, the CG channel keeps closed so that the photoresponse is only active for SG controlled region, resulting in high linear sensitivity, while the CG channel will automatically turn on when the illumination is strong enough. Correspondingly, the CG controlled region is connected with SG controlled region for photoresponse together, resulting in a relatively lower linear sensitivity. For very strong illumination, the 1T-APS will automatically switch to logarithmic response mode due to the activated virtual photodiode in the FD-SOI substrate. The sensitivity transition points in the linear–linear region and the linear–logarithmic region can be further adjusted by the bias of CG and back gate, respectively. The adjustable self-adaptive sensitivity indicates the great potential of the proposed 1T-APS for high-quality image sensing.

Super-Regenerative Oscillator Integrated Metamaterial Leaky Wave Antenna for Multi-Target Vital Sign and Motion Detection

A new kind of metamaterial (MTM) leaky wave antenna (LWA) integrated with a super-regenerative oscillator (SRO) architecture is proposed for the first time. As a proof of concept, the proposed radar sensor, including a one-dimensional (1D) MTM LWA and a tunable voltage-controlled oscillator (VCO), is designed to perform frequency-dependent space mapping with the main-beam angle sweeping from −50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ $</tex-math></inline-formula> to +30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ $</tex-math></inline-formula> with respect to the varying frequency from 1.85 to 2.85 GHz. The proposed SRO-integrated MTM LWA system is operated in the logarithmic mode with a quench signal imposed at the drain port of transistor. Experiments have been conducted to show that vital sign information for two human targets can be successfully detected when they are located along different scanning angles of −10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ $</tex-math></inline-formula> and −30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\circ $</tex-math></inline-formula> , respectively. Furthermore, compared with MTM LWA radar sensor based on the self-injection-locked (SIL) architecture, vibrating motion at a farther distance can be detected accurately using the proposed radar sensor, indicating a higher sensitivity with reduced system complexity.

Research on Channel Modeling and Communication Coverage of Wireless Sensor Networks in Barrier Area of Nuclear Power Plants

In view of the multimetal barrier environment of nuclear power plant, by considering the factors such as transmission power, transmission position, and multipath interference, based on the simulation of metal pipes and equipment, this paper carries out the barrier area channel modeling in logarithmic fading mode and makes quantitative analysis on the channel transmission, path loss, channel power characteristics, and so on under the metal barrier environment. Based on the channel modeling, this paper optimizes the coverage of the network in the obstacle area by using the improved teaching and learning group intelligent algorithm. The simulation results show that the improved teaching and learning algorithm can optimize the network coverage of the obstacle area well, and under the four obstacle modules, 14 nodes can cover the whole area by more than 99%. This provides a solution to the problem of network coverage in the practical application of wireless sensor networks.

Super-Regenerative Oscillator-Based High-Sensitivity Radar Architecture for Motion Sensing and Vital Sign Detection

A radar sensor architecture based on a super-regenerative oscillator (SRO) with very high sensitivity is presented for vital sign detection and motion sensing. As a proof of concept, the proposed SRO-based radar sensor architecture, operating in its logarithmic mode, incorporates a patch antenna as a frequency-selective network to transmit and receive radio frequency (RF) signals at 2.32 GHz to conduct target sensing. In this prototype, a common source heterojunction (HJ)-FET is adopted as a variable-gain amplifier in the positive feedback loop of SRO, where two quench signals, 200 Hz and 10 KHz, are employed respectively at the gate of the transistor to periodically modulate the oscillation condition. Furthermore, the theoretical analysis for the radar signal gain of the proposed SRO radar sensor is carried out, demonstrating a 20 dB/decade voltage gain with respect to the input signal reflected from the target. Thanks to the intrinsic automatic gain control characteristic of SRO, the voltage gain of radar signal can go beyond 100 dB in theory. To this end, the measured voltage gain of radar signals with different quench frequencies of the SRO is compared with the theoretical values in the logarithmic mode, exhibiting a maximum gain of 70 dB in the experiment. In addition, compared with the self-injection-locked (SIL) architecture, the experimental results show that the proposed SRO-based radar sensor can exhibit 34–39 dB voltage gain improvement, thereby detecting the actuator movement and vital sign signals of human target accurately at a longer distance with higher sensitivity and reduced circuit complexity.

A novel linear-logarithmic readout integrated circuit with high dynamic range

This paper presents a novel pixel structure of readout integrated circuit (ROIC) for infrared focal array plane (IRFPA). The pixel can operate in the linear-logarithmic mode to reach high dynamic range. The pixel is based on the buffered direct injection (BDI) as the input cell. The logarithmic response is realized by adding two additional diode-connected MOSFETs. The pixel can automatically switch between the linear and the logarithmic mode. The threshold voltage of the mode-switching is controlled by a given voltage. A linear-logarithmic test chip consisting of a small pixel array has been designed and fabricated using Global Foundry 0.18 μm 1P6M process. A medium wave infrared detector has been hybridized to the chip. The experimental results show that the logarithmic sensitivity is 86 mV/dec. The dynamic range of the chip is higher than 137 dB and the dynamic range of the chip with a detector is greater than 102 dB.

Anomalous gravitation and its positivity from entanglement

We explore the emergence of gravitation from entanglement in holographic CFTs with gravitational anomalies. More specifically, the holographic correspondence between topologically massive gravity (TMG) with gravitational Chern-Simons term in the 3D bulk and its dual CFT with unbalanced left and right moving central charges on the 2D boundary, is studied from the quantum entanglement perspective. Using the first law of entanglement, we derive the holographic dictionary of the energy-momentum tensor in TMG, including the chiral case with logarithmic mode. Furthermore, we show that the linearized equation of motion of TMG can also be obtained from entanglement using the Wald-Tachikawa covariant phase space formalism. Finally, we identify a quasi-local gravitational energy in the entanglement wedge as the holographic dual of relative entropy in gravitationally anomalous CFTs. The positivity and monotonicity of relative entropy imply that such a gravitational energy should be positive definite and become larger when increasing the size of the entanglement wedge. These constraints from quantum information may be potentially used to discuss the UV inconsistent issues of TMG.

Spectral Noise Analysis of a CMOS Imager at Low Temperature for Logarithmic Mode

The most common and useful CMOS high-dynamic-range imager is the one employing the active pixel sensor (APS) operating in the logarithmic mode. Notwithstanding, temporal noise can compromise the quality of the image generated by the focal-plane array. Most of the image-sensor noise models and results found in the literature are limited to a temperature range higher than that of the freezeout temperature, where the semiconductor doping impurities are all activated. The focus of this paper is to compare the noise spectrum behavior of the logarithmic image sensor at room temperature with that of a temperature near and below the freezeout point. Experimental results carried out in a small bidimensional pixel array fabricated in a standard 4-metal 2-poly 0.35- $\mu \text{m}$ CMOS technology suggests that thermal noise remains quite steady as the temperature reduces due to the increase in the sense-node resistance of the pixel circuitry. On the other hand, “spikes” have been identified with significant intensity in the spectral noise in all pixels when studied individually. These spikes in the spectrum have the same value in frequency when the device is submitted to different light intensities and temperatures. However, they were only observed for temperatures below 150 K and for frequencies below the corner frequency. The nonrandomic presence of these spikes in the noise spectrum indicates the presence of traps related to the defects inside the gate oxide and at the oxide–silicon interface. At room temperature, these spikes are not observed due to the thermal energy being higher than the binding energy of these traps.

An Analytical Model for Capturing the Decline of Fracture Conductivity in the Tuscaloosa Marine Shale Trend from Production Data

Fracture conductivity decline is a concern in the Tuscaloosa Marine Shale (TMS) wells due to the high content of clay in the shale. An analytical well productivity model was developed in this study considering the pressure-dependent conductivity of hydraulic fractures. The log-log diagnostic approach was used to identify the boundary-dominated flow regime rather than the linear flow regime. Case studies of seven TMS wells indicated that the proposed model allows approximation of the field data with good accuracy. Production data analyses with the model revealed that the pressure-dependent fracture conductivity in the TMS in the Mississippi section declines following a logarithmic mode, with dimensionless coefficient χ varying between 0.116 and 0.130. The pressure-dependent decline of fracture conductivity in the transient flow period is more significant than that in the boundary-dominated flow period.

A &lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$K$ &lt;/tex-math&gt; &lt;/inline-formula&gt;-Band SiGe Superregenerative Amplifier for FMCW Radar Active Reflector Applications

A $K$ -band integrated superregenerative amplifier (SRA) in a 130-nm SiGe BiCMOS technology is designed and characterized. The circuit is based on a novel stacked transistor differential cross-coupled oscillator topology, with a controllable tail current for quenching the oscillations. The fabricated integrated circuit occupies an area of 0.63 mm2, and operates at the free-running center frequency of 25.3 GHz. Characterization results show circuit operation from a minimum input power level required for a phase coherent output as −110 dBm, and the input power level corresponding to the linear to logarithmic mode transition of −85 dBm, the lowest reported for $K$ -band integrated logarithmic mode SRAs to date to the knowledge of the authors. The measured output power is +7.8 dBm into a 100 $\Omega$ differential load. The power consumption of the circuit is 110 mW with no quench signal applied, and 38 mW with 30% duty cycle quenching. The quench waveform designed for the reported measurement result is also discussed.

A Charge Compensation Phototransistor for High-Dynamic-Range CMOS Image Sensors

This paper presents a charge compensation phototransistor for high-dynamic-range CMOS image sensors (CIS). With a built-in charge compensation mechanism, the photoresponse of the proposed device can switch between the linear mode and the logarithmic mode automatically, according to the incident light intensity. In particular, the device does not saturate until approximately 0.5 W/cm2, almost 5 times the brightness of the sun. Therefore, CIS with this proposed phototransistor demonstrates a measured dynamic range of 167 dB, and an output swing of more than 2 V without amplification. The nonideal behavior of the proposed device due to the thermal effect and the parasitic resistances is investigated when exposed with high incident light intensity. In addition, the nonuniform response of the pixel array is exhibited and analyzed.

Melt-spun Liquid Core Fibers: A CFD Analysis on Biphasic Flow in Coaxial Spinneret Die

Simulation of co-flowing behavior in a coaxial geometry (based on the designed spin pack) has been performed using properties of two immiscible liquids to represent flowing regime while passing through the spinneret for production of liquid core fiber (LCF) by one single step high-speed melt-spinning process. Computational Fluid Dynamics (CFD) simulations confirmed the continuous liquid core channel, obtained in bicomponent melt-spinning of LCF. Also different interface morphologies could be observed: from jetting to dripping and transition core-annular regime, based on the simulation parameters, affecting the driving forces. Results showed different co-flow regimes by systematic variation in nondimensional parameters (flow rate ratio, viscosity ratio, Reynolds number, Weber number and Capillary number), individually. Also diameter of the core liquid is reduced in a logarithmic mode by increasing the outer liquid’s flow rate. Flowing morphologies at different conditions were plotted in 2D state diagrams, illustrating transition from dripping to jetting regime by changing two different parameters. This CFD analysis bears potential for simple ways of controlled jet breakup in microfluidic devices, which currently primarily rely on Rayleigh-Taylor breakup. Notably this work highlights the melt-flow regime in the spinneret to realize developed fiber core structures at different conditions during bicomponent melt-spinning. Using various materials with different properties in liquid core fiber production promises many applications for this new generation fiber in very near future.

160 dB dynamic range pixel with charge compensation for CMOS image sensor

A 160 dB high dynamic range pixel architecture with charge compensation technique for CMOS image sensor (CIS) is presented. Employing a built-in charge compensation photodiode, the operation mode of the proposed pixel can switch between linear mode and logarithmic mode automatically according to the incident light intensity. The measured result shows a CIS with the proposed pixel architecture has a dynamic range up to 160.9 dB with an output swing of 1.9 V. Moreover, this scheme does not require complex control circuits and complicated timing sequence.

Voltage Mode FPN Calibration in the Logarithmic CMOS Imager

The CMOS active pixel sensor (APS) operating in the logarithmic mode is the most common and useful CMOS wide-dynamic-range imager. Notwithstanding, fixed-pattern noise (FPN) between pixels compromises the quality of the image generated by the focal-plane array. Classical techniques as correlated double sampling do not work properly in this mode, and alternative techniques must be applied in order to calibrate FPN. The alternative techniques require either complex pixel circuitry, or external memory and software level calibration. Purposefully to improve image quality at reduced circuitry complexity, a new calibration technique is proposed that can be applied directly to the basic three-FET APS circuit. The efficacy of the proposed technique was experimentally verified with a small pixel array fabricated in a standard 0.35- $\mu \text{m}$ CMOS technology. The experimental results show a steady FPN attenuation within the whole tested illumination range and the improvement of the signal-to-noise and distortion ratio of the array.

ProMCC: An all-in-one tool for trace metal complexation studies

A new windows-based, user friendly program (ProMCC) for (i) the determination of metal complexation parameters (ligand concentration (L) and conditional stability constants (K′)) and for (ii) theoretical simulation of metal complexometric titration, assuming discrete ligand model, is developed. Although primarily intended for treatment of experimental data obtained either by anodic stripping voltammetry (ASV) or competitive ligand exchange adsorptive cathodic stripping voltammetry (CLE-AdCSV), it could manage titration-type data of other techniques (e.g. ISE, sorption isotherm). Currently, the program is capable to process (fit and/or simulate) titration data up to three discrete ligand classes. Procedure for adjustment of “true” analytical sensitivity incorporated in ProMCC was found to provide reasonably good estimates of sensitivity either for one-ligand or two-ligand system. The particular feature of ProMCC is that it incorporates two complementary fitting methodologies: (1) a non-linear fitting of conventional linearized transformations (e.g. Ružić/Van Den Berg, Langmuir/Gerringa) and (2) a “complete complexation model” — a matrix based optimization of mass balance equations. Comparison test of different non-linear fitting modes and titration types revealed that a slight underestimation of ligand concentration and overestimation of conditional stability constant may occur if titration is performed in logarithmic mode, mainly due to unfavorable noise distribution. An advantage of implemented “complete complexation model” fitting mode is that it allows simultaneous analysis of titrations obtained at multiple detection windows as unified dataset (multi-detection window approach), providing complexation parameters for up to three ligand classes. A new alternative “RAL-approach” in analyzing complexometric titrations obtained at multiple detection windows for copper–salicylaldoxime (Cu–SA) system is suggested. It assumes that the analytical sensitivity is changing along the titration curve respecting the true speciation of Cu–SA in sample. An adapted empirical equation for calculation of relative intensity (RAL) is proposed. Flexibility in adjusting parameters, immediate graphical feedback and visualizations make ProMCC handy for treatment of large set of experimental data, and a tool for research in refinement of the methods of metal complexing capacity determination which is continuously improving.

Holographic Rényi entropy in AdS3/LCFT2 correspondence

The recent study in AdS$_3$/CFT$_2$ correspondence shows that the tree level contribution and 1-loop correction of holographic R\'enyi entanglement entropy (HRE) exactly match the direct CFT computation in the large central charge limit. This allows the R\'enyi entanglement entropy to be a new window to study the AdS/CFT correspondence. In this paper we generalize the study of R\'enyi entanglement entropy in pure AdS$_3$ gravity to the massive gravity theories at the critical points. For the cosmological topological massive gravity (CTMG), the dual conformal field theory (CFT) could be a chiral conformal field theory or a logarithmic conformal field theory (LCFT), depending on the asymptotic boundary conditions imposed. In both cases, by studying the short interval expansion of the R\'enyi entanglement entropy of two disjoint intervals with small cross ratio $x$, we find that the classical and 1-loop HRE are in exact match with the CFT results, up to order $x^6$. To this order, the difference between the massless graviton and logarithmic mode can be seen clearly. Moreover, for the cosmological new massive gravity (CNMG) at critical point, which could be dual to a logarithmic CFT as well, we find the similar agreement in the CNMG/LCFT correspondence. Furthermore we read the 2-loop correction of graviton and logarithmic mode to HRE from CFT computation. It has distinct feature from the one in pure AdS$_3$ gravity.