Input Slope Research Articles

Combined effect of the magnetic field, orientation, and filling ratio on cylindrical pulsating heat pipe using distilled water and distilled water/Fe3O4 nanofluid

To investigate the effect of the magnetic field, a pulsating heat pipe was made in the shape of a cylinder and Fe3O4 nanoparticles (%0.1 wt) were used with the base fluid of distilled water as the working fluid. (Tetramethyl ammonium hydroxide) TMAH surfactant was used as a stabilizer. To investigate the effect of gravity on the performance of the pipe, the device was tested at different angles from zero to 90 degrees. In this research, the effect of different variables, including the type of working fluid (distilled water vs. nanofluid), filling ratio, slope, and amount of heat input to the evaporator (30–300 W), in two different states, once without the influence of the magnetic field and once again with the application of a magnetic field was investigated. The results of the tests showed that the performance of the device at 50 % filling ratio is better than 60 % filling ratio. The use of nanoparticles improved the performance of the device. Inclining the device increases the thermal resistance so that the device performs poorly in the horizontal mode in all modes except when it is under the influence of a magnetic field. The use of nanofluid as well as the application of a magnetic field makes the start-up time of the device decrease by 37 % and 30 %, respectively, compared to distilled water. The temperature of the start of fluctuations also decreases by 24 % and 32 %, respectively.

Design Development of Detection System and Ro-Ro Ship Notification based on Fuzzy Inference System

Ship stability is very important for the safety of ship motion. There are many factors that affect the stability of a ship. One of the causes of accidents on ships is the problem of ship stability, including the ship cannot be controlled, and loses balance due to improper placement of cargo loads. This study combines gyroscopes, accelerometers, compasses, and GPS sensors, so that more accurate ship tilt information is obtained through an Android smartphone application. This study uses the fuzzy inference system (FIS) method with a trapezoidal membership function where there are 2 inputs and 1 output. Ship tilt input uses 3 linguistic variables very tilted, tilted, and stable. The slope duration input uses 5 very fast, fast, fairly fast, slow, and very slow linguistic variables. Ship status output is divided into 3 linguistic variables safe, alert, and dangerous. Testing and implementation with an input slope of 4.8 and a slope duration of 10 seconds using the Sugeno fuzzy method, the ship's crips value of 0.65 with an alert status was obtained. Calculation of the accuracy of the gyroscope sensor error using the MAPE method, the result is an error percentage of 6.55% (very good). The system accuracy error of 39 trials (36 correct and 3 incorrect) is 92.30% (very good). This research is expected to make it easier for the captain to monitor the stability of the ship and can provide notification of the status of the ship to the captain of the ship if there is a condition of the ship that needs to be watched out for. In addition, the notification will also be received by Port officers on land.

An IF-Sampling CMOS S/H Calibration Technique With Analog HPF Slope Estimation

We present a calibration technique to correct the dominant dynamic tracking nonlinearity of CMOS sample-and-hold (S/H) circuits for IF-sampling applications. The error model, derived from the asymmetrical drain/source drive of a clock-bootstrapped switch, is exclusively dependent on the S/H output voltage and its slope. A simple analog high-pass filter (HPF) is used to extract the input slope voltage slope, obviating computationally intensive digital interpolation filters often employed in such applications. A prototype S/H chip fabricated in a 65-nm CMOS process measures an SFDR of ~100 dB for an fin = 300 MHz and of >85 dB for an fin = 500 MHz.

OzDES reverberation mapping program: Lag recovery reliability for 6-yr C iv analysis

ABSTRACT We present the statistical methods that have been developed to analyse the OzDES reverberation mapping sample. To perform this statistical analysis we have created a suite of customizable simulations that mimic the characteristics of each source in the OzDES sample. These characteristics include: the variability in the photometric and spectroscopic light curves, the measurement uncertainties, and the observational cadence. By simulating the sources in the OzDES sample that contain the C iv emission line, we developed a set of criteria that rank the reliability of a recovered time-lag depending on the agreement between different recovery methods, the magnitude of the uncertainties, and the rate at which false positives were found in the simulations. These criteria were applied to simulated light curves and these results used to estimate the quality of the resulting Radius–Luminosity relation. We grade the results using three quality levels (gold, silver, and bronze). The input slope of the R–L relation was recovered within 1σ for each of the three quality samples, with the gold standard having the lowest dispersion with a recovered a R–L relation slope of 0.454 ± 0.016 with an input slope of 0.47. Future work will apply these methods to the entire OzDES sample of 771 AGN.

Robotic arm joint position control using iterative learning and mixed sensitivity H∞ robust controller

This paper proposes an improved control strategy of a robotic arm joint using hybrid controller consist of H∞ robust controller and iterative learning controller. The main advantage of this controller is the simple structure that made it possible to be implemented on a small embedded system for frugal innovation in industrial robotic arm development. Although it has a simple structure, it is a robust H∞ controller that has robust stability and robust performance. The iterative learning controller makes the trajectory tracking even better. To test the effectiveness of the proposed method, computer simulations using Matlab and hardware experiments were conducted. Variation of load was applied to both of the processes to present the uncertainties. The superiority of the proposed controller over the proportional integral derivative (PID) controller that usually being used in a low-cost robotic arm development is confirmed that it has better trajectory tracking. The error tracking along the slope of sinusoidal trajectory input was suppressed to zero. The biggest error along the trajectory that happened on every peak of the sinusoidal input, or when the direction is changed has been improved from 15 degrees to 4 degrees. This can be conceived that the proposed controller can be applied to control a low-cost robotic arm joint position which is applicable for small industries or educational purpose.

All-digital successive approximation TDC in time-mode signal processing

The need for low-power high-resolution ADCs in a broad range of emerging applications and the architecture to realize these ADCs are examined. The pros and cons of various TDC architectures namely flash TDC, Vernier TDC, ΔΣ TDC, and SAR TDC are compared and their suitability for implementing hybrid ADCs to achieve low power and high resolution is investigated. An 8-bit time-mode SAR TDC targeting hybrid ADCs is proposed. The proposed SAR TDC uses a pair of 16-stage pre-skewed delay lines with 16-level digital time interpolation to achieve the targeted resolution and desired power efficiency. The impact of the degree of pre-skewing on both resolution and power consumption is investigated. The nonlinearity of the pre-skewed delay lines is also investigated, along with the impact of PVT uncertainty. The nonlinearity of the digital time interpolators and the impact of PVT uncertainty on time interpolators are also studied. Factors affecting the linearity of digital time interpolators including input-output isolation and input slope are investigated. A detailed treatment of the timing errors arising from device noise and mismatch is provided. The SAR TDC is designed in a TSMC 65 nm 1.0 V CMOS technology and analyzed using Spectre with BSIM3.3 device models. Simulation results show the SAR TDC operated at 10 MS/s achieves 0.33 ps resolution, 84.8 ps measurement range, 7-bits ENOB, and 1.30 pJ/conversion power efficiency.

Adaptive Estimation of Play Radii for a Prandtl–Ishlinskii Hysteresis Operator

The Prandtl–Ishlinskii (PI) operator is a mathematical model for hysteresis, and it is comprised of weighted superposition of multiple play (backlash) operators. The PI operator has been widely used in modeling and compensation of hysteresis in smart material actuators, robots, and mechanical systems. The behavior of a PI operator is determined by both the weights and the radii of individual play operators. However, existing modeling work has mostly been focused on the identification of the weight parameters by assuming the play radii to be known. While the latter approach is convenient due to the linear relationship between the operator output and the weight parameters, it often requires a large number of plays with preassigned radii in order to adequately capture the hysteresis in a given application. In this work, for the first time, we propose an adaptive estimation algorithm to identify the play radii of a PI operator, to enable accurate modeling of hysteresis with a small number of plays and, thus, reduce the complexity in control. The major challenge lies in the nonlinear, complex, time-varying relationship between the PI operator output and the play radii. The proposed algorithm utilizes available measurement and information, including the instantaneous slope of the hysteretic input–output graph, to derive a modified estimation error function that is proportional to the parameter error. With a mild condition on the input, we establish the persistent excitation of the resulting regressor vector and the parameter convergence under a gradient algorithm with parameter projection. Both simulation and experimental results are presented to illustrate the proposed approach. In particular, comparison results based on experimental data from a piezoelectric nanopositioner show that, with the proposed method, the resulting PI operator outperforms identified PI operators of larger numbers of plays with preassigned radius values.

Improving Analytical Delay Modelingfor CMOS Inverters

Analytical methods for gate delay estimation are very useful to speedup timing analysis of digital integrated circuits. This work presents a novel approach to analytically estimate the CMOS inverter delay. The proposed method considers the influence of input slope, output load and I/O coupling capacitance, as well as relevant effects such as channel length modulation and drain induced barrier lowering. Experimental results are on good agreement with HSPICE simulations, showing significant accuracy improvement compared to published related work. The delay model error has an average value of 3%, and the worst case error is smaller than 10%.

Slope Stability of Landfill with Waste Degradation

Nowadays, a large amount of municipal solid waste (MSW) is generated due to the rapid urbanisation in developing countries leads to the demand for larger and higher capacity landfills. Bioreactor landfill technology has been introduced to accelerate the stability of landfill and to solve the issue of limited landfill area. However, the accelerated degradation of the refuse in bioreactor landfills also considerably changes the geotechnical characteristics of the waste in the landfill and thereby increases the concern for waste stability. Hence, this study aims to analyse the stability of both conventional and bioreactor landfill slope with the effects of waste degradation. Finite element method has been used in the slope stability analysis and the stability is presented by the factor of safety. The objectives of this study are i) to determine and assess the main parameter which influences the stability of the waste slope, ii) to determine the effects of waste degradation to the waste properties and iii) to obtain the factor of safety of the landfill slope using numerical analysis by finite element method. From the literature review, it is found that slope stability of a landfill mainly depends on the geotechnical properties of waste, such as moisture content, unit weight, shear strength parameters and hydraulic conductivity of waste. After the degradation process, engineering properties of field refuse are affected which includes the increased pore-water pressure and unit weight, decreased strength and lower hydraulic conductivity. Based on the analysis of conventional landfill slope stability by using Plaxis software, slope ratio of 1:3, 1:4 and 1:5 calculated safe with 1.69, 2.3 and 2.8 whereas the analysis of bioreactor landfill slope stability calculated safe only for slope ratio of 1:4 and 1:5 with 1.60 and 1.97. Moreover, the factor of safety for steeper slopes is lower and vice versa. From the parametric analysis, it is found that the full height of slope and unit weight of waste input affect the result analysis. This study is significant to evaluate the landfill slope stability with the effects of waste degradation and to ensure both conventional and bioreactor landfill slope stability for long periods.

A 12-b 1-GS/s 31.5-mW Time-Interleaved SAR ADC With Analog HPF-Assisted Skew Calibration and Randomly Sampling Reference ADC

This paper presents a 12-b, 1-GS/s ADC array, realized by time-interleaving four 250-MS/s pipelined SAR ADCs, with integrated on-chip reference voltage buffers. A reference ADC-based calibration algorithm treats static nonlinearity, gain, and offset errors in the array. Timing-skew errors between the sub-ADCs are distinguished from those of the gain mismatches by the assistance of an analog high-pass filter (HPF) for input slope information and subsequently corrected by digitally controlled delay lines (DCDLs). Directly driven off the on-chip 50- $\Omega $ termination resistors without any dedicated input buffer, the 65-nm CMOS prototype ADC array also employs a frequency-hopped, randomly-sampling scheme for the ref. ADC, eliminating the spectral effect of its interference to the main array. The core ADC consumes 31.5 mW and occupies an area of 0.27 mm2, including nine on-chip reference voltage buffers, the ref. ADC, and the HPF path. The measured peak signal to noise and distortion ratio of the array is 65.3 dB, and the measured spurious-free dynamic range is >70 dB from dc to 500 MHz at 1 GS/s with calibration. The prototype ADC chip achieves an figure of merit of 20.9 and 59.7 fJ/step (the latter is limited by the jitter of an off-chip clock source) for a low-frequency input and a Nyquist input, respectively.

Retrieval of spectral backscattering from spectral scattering based on spectral partitioning technique

Direct measurement of backscattering using sensors has technological limitations such as saturation in highly turbid waters and the effect of absorption in strongly absorbing highly productive waters. In the present study, a quantitative method is developed to estimate the particulate spectral backscattering coefficient based on spectral partitioning of the scattering coefficient. The input slope of the non-algal backscattering spectra was determined from the scattering slope and the magnitude was quantified from the water turbidity. The contribution of phytoplankton to the backscattering was determined as a linear combination of the spectral dependency factors and the chlorophyll concentration. The proposed method of conversion, from scattering to backscattering, when compared with two existing methods (Haltrin and Petzold average ratio), resulted in lower relative errors (mean relative error: -0.214–0.037, mean net Bias: -0.259–0.019, root mean square error: 0.006–0.015, coefficient of determination: 0.91–0.98), and substantial improvement was also observed in the spectral shape and magnitude of the backscattering coefficients.

Linear and Resolution Adjusted On-Chip Aging Detection of NBTI Degradation

Accurate detection of nanometer CMOS circuits is one of the most critical issues for tolerating the negative bias temperature instability (NBTI). In this paper, a fully digital on-chip aging detector, which achieves a direct correlation between the threshold voltage degradation ( ${\Delta }$ Vth) and the phase difference, has been proposed. The linear correlation is realized based on our revised Schmitt triggers in which the stressed and the fresh devices are embedded. Moreover, the readout circuit has been designed to count, lock, and output the samples through a parallel-to-serial converter. The main contributions include: 1) good linear correlation between ${\Delta }$ Vth and the pulse width is provided; 2) the measurement resolution can be adjusted by changing the input slope; and 3) the circuits are almost independent to process and voltage due to the symmetrical structure and layout matching. The prototype chip has been fabricated in a 1.1 V, 36-nm CMOS technology. The measured equivalent resolution is 3.4 ns/mV under $1~{\mu }\text{s}$ rise-time sawtooth input, which is sufficient to suppress the unwanted recovery. Compared with the traditional testing, the proposed detector can satisfy the surveillance of NBTI degradation. This flexible architecture can be easily revised to accommodate other aging mechanisms, such as PBTI and HCI.

Integrated multi-parameter approach for delineating groundwater potential zones in a crystalline aquifer of southern India

Groundwater resources in the semi-arid regions of southern India are under immense pressure due to large-scale groundwater abstraction vis-a-vis meager rainfall recharge. Therefore, understanding and evaluating the spatial distribution of groundwater is essential for viable utilization of the resource. Here, we assess groundwater potential at the watershed scale, in a semi-arid environment with crystalline aquifer system without a perennial surface water source using remote sensing, geophysical, and GIS-based integrated multi-parameter approach. GIS-based weighed overlay analysis is performed with input parameters, viz., geology, geomorphology, lineament density, land use, soil, drainage density, slope, and aquifer thickness. The watershed is categorized into four zones, namely, “very good” (GWP4), “good” (GWP3), “moderate” (GWP2), and “low” (GWP1) in terms of groundwater potential. Overall, ~ 70% of the study area falls under moderate to low groundwater potential, indicating a serious threat to the future availability of the resource. Therefore, serious measures are required for maintaining aquifer resilience in this over-exploited aquifer (e.g., restricting groundwater withdrawal from GWP1 and GWP2 zones). Further, as the aquifer is under tremendous anthropogenic pressure, rainwater harvesting and artificial recharge during monsoon are advocated for sustainable aquifer management. Due to the direct dependence of crop production vis-a-vis farmer economy on groundwater, this study is an important step towards sustainable groundwater management and can be applied in diverse hydrological terrains.

Fast Background Calibration of Sampling Timing Skew in SHA-Less Pipeline ADCs

This brief presents a digital calibration technique for compensating timing-skew errors between the sub-ADC and the MDAC in the first stage of sample-and-hold amplifier (SHA)-less pipeline ADCs. In the presence of clock-skew errors, sub-ADC comparators produce time-variant offsets depending on the input-signal slope at the sampling instants. These increase residue excursions at the MDAC output, potentially causing overranging and an increment in nonlinear errors. This paper derives close analytical expressions for these effects. The proposed method uses the overranging information to perform a low-cost estimation and correction of the skew error with the following features: 1) very fast convergence (in the order of 1-k input samples); 2) indirect evaluation of the skew error signal, without any previous knowledge of the input signal’s frequency distribution; and 3) relatively simple digital logic—basically, two digital comparators and one small accumulator. The method was verified in behavioral and transistor-level simulations. As a demonstrator, its implementation in a 1.8-V 80-dB SNDR 100-Msps SHA-less pipeline ADC in a 0.18- $\mu \text{m}$ CMOS process is shown.

T022 Shaping the temporal characteristics of transcranial magnetic stimulation

The pulse waveform of transcranial magnetic stimulation (TMS) affects the degree to which various neuronal elements and populations are activated as well as the strength of neuromodulation resulting from repetitive TMS. Conventional TMS devices allow very limited pulse waveform adjustment; therefore we developed TMS devices with controllable pulse parameters (cTMS). So far cTMS has been used, by our and other groups, to study strength-duration curves in motor cortex and the associated neural membrane time constants; pulse-width dependence of motor input–output curves, cortical neuron recruitment, paired-pulse paradigms, and scalp sensation; and pulse-shape dependence of neuromodulatory effects. These studies show that changing the pulse width, shape, and/or direction may alter the neural elements that are preferentially activated in cortex, as evidenced by differences in motor evoked potential latencies and membrane time constants. These parameters also affect the changes of neural excitability resulting from 1 Hz and intermittent theta burst stimulation. For the 1 Hz protocol, the near rectangular cTMS pulses produced stronger inhibition than conventional sinusoidal pulses, with unidirectional cTMS pulses having the strongest effect. As well, cTMS has been used to optimize new repetitive paired-pulse stimulation protocols. cTMS was also used to show that the slope of motor input–output curves depends on pulse width via the same mechanism driving the strength-duration relationship of motor threshold. Finally, the pulse width affects the perceived scalp sensation of TMS, with briefer pulses feeling sharper and slightly more uncomfortable than longer pulses. In parallel with exploring the capabilities afforded by cTMS, we are developing a next generation ultraflexible TMS device called a modular pulse synthesizer (MPS) that would allow the generation of essentially any pulse shape and pulse sequence/train within the energy levels practical for TMS. The development and adoption of cTMS and MPS could enable expanded utilization of the temporal characteristics of TMS as a means of enhancing functional targeting, noninvasive biomarkers, neuromodulatory potency, and tolerability.

Maintenance of balance between motor cortical excitation and inhibition after long-term training

Motor learning with professional experience leads to cortical reorganization with plasticity. Long-term training facilitates motor cortical excitability. It is not clear how beneficial cortical plasticity is maintained during long-term training. We studied this question in 15 elite badminton athletes and 15 novices. We hypothesize that motor cortical excitation increases after long-term training and this is accompanied by increased motor cortical inhibition. Motor cortical excitation was measured with motor-evoked potential (MEP) input–output curve using transcranial magnetic stimulation (TMS). Motor cortical inhibition was measured with short-interval intracortical inhibition (SICI) and long-interval intracortical inhibition (LICI) by a paired-pulse TMS paradigm. We found MEP was increased at high TMS intensity and the MEP input–output curve was steeper in athletes compared to novices. Both SICI and LICI were also increased in athletes. In addition, both SICI and LICI were correlated with the slope of MEP input–output curve in athletes but not in novices. The slope of MEP input–output curve, SICI and LICI were also correlated with the training time in athletes. We conclude that both cortical excitation and cortical inhibition are increased, and that the balance between cortical excitation and inhibition is maintained during long-term training.

Downstream Effect of Ramping Neuronal Activity through Synapses with Short-Term Plasticity.

Ramping neuronal activity refers to spiking activity with a rate that increases quasi-linearly over time. It has been observed in multiple cortical areas and is correlated with evidence accumulation processes or timing. In this work, we investigated the downstream effect of ramping neuronal activity through synapses that display short-term facilitation (STF) or depression (STD). We obtained an analytical result for a synapse driven by deterministic linear ramping input that exhibits pure STF or STD and numerically investigated the general case when a synapse displays both STF and STD. We show that the analytical deterministic solution gives an accurate description of the averaging synaptic activation of many inputs converging onto a postsynaptic neuron, even when fluctuations in the ramping input are strong. Activation of a synapse with STF shows an initial cubical increase with time, followed by a linear ramping similar to a synapse without STF. Activation of a synapse with STD grows in time to a maximum before falling and reaching a plateau, and this steady state is independent of the slope of the ramping input. For a synapse displaying both STF and STD, an increase in the depression time constant from a value much smaller than the facilitation time constant τ(F) to a value much larger than τ(F) leads to a transition from facilitation dominance to depression dominance. Therefore, our work provides insights into the impact of ramping neuronal activity on downstream neurons through synapses that display short-term plasticity. In a perceptual decision-making process, ramping activity has been observed in the parietal and prefrontal cortices, with a slope that decreases with task difficulty. Our work predicts that neurons downstream from such a decision circuit could instead display a firing plateau independent of the task difficulty, provided that the synaptic connection is endowed with short-term depression.

Two-Degree-of-Freedom Hysteresis Compensation for a Dynamic Mirror Actuator

A low-computation, high-bandwidth, inverse-based hysteresis compensation and control strategy, not needing a priori knowledge of the desired trajectory, is presented. The resulting two degree-of-freedom controller is applied to a dynamic mirror with antagonistic piezoelectric stack actuation. Hysteresis compensation is performed by a finite-state machine activating polynomials for hysteresis inversion based on input signal slope. Residual error after hysteresis compensation is corrected by an LQR feedback controller. Experimental results demonstrate effectiveness of the hysteresis compensator and closed-loop system. For the input signal tested, a 91.5% reduction in hysteresis uncertainty is achieved at a 60 kHz sample rate.

Accurate and cost‐effective technique for jitter and noise separation based on single‐frequency measurement

A simple and cost-effective technique is proposed for jitter and noise separation in ADC test. On the basis of the property that clock jitter is modulated by the slope of input signal, few simple mathematical manipulations are performed on a single data record of ADC output to separate jitter and noise. The proposed method requires only one high-frequency signal test and eliminates the need for a second low-frequency test in conventional dual-frequency jitter tests. Compared with existing single-frequency test, the new method is accurate and robust to non-harmonic distortion, without requiring any additional data acquisition time. Therefore, both hardware overhead and data acquisition time are saved significantly. Experimental results show that both jitter and signal-to-noise ratio are estimated accurately, and the accuracy of jitter estimation is comparable with that of conventional dual-frequency test.

Drought Tolerance Selection of Sugarbeet Hybrids

Increased water demands and drought have resulted in a need to indentify crop hybrids that are drought tolerant, requiring less irrigation to sustain yields. This study was conducted to assess differences in drought tolerance among a group of genetically diverse sugarbeet hybrids. The study was conducted over three consecutive growing seasons (2008-2010) at the USDA Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho on a Portneuf silt loam soil (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid). Drought tolerance was evaluated by measuring sucrose yield production of six breeding hybrids of Klein Wanzlebener Saatzucht (KWS SAAT AG) and one commercial hybrid (Betaseed Inc.) under six water input treatments. Hybrid drought tolerance was evaluated by linear regression analysis (slope and intercept) of yield versus water input, calculation of a drought stress index (DSI), and comparison of yield potential under full irrigation. The water input treatments were based on a percentage of estimated crop evapoatransipration (ETc). Water input treatments were 125% ETc (W1), 100% ETc (W2), 75% ETc (W3), 50% ETc (W4), 25% ETc (W5) and rain-fed (W6). Irrigation was applied three times a week to meet the desgnated rate. There were significant differences in overall yield potential and in the sucrose yield response to water among hybrids. Greater drought tolerance or greater difference in sucrose yield between hybrids was seen at the lowest water input treatment (intercept difference). Greater drought tolerance was observed for the KWS-05 hybrids compared to the commercial hybrid. Based on these results there exist genetic diversity among existing sugarbeet breeding hybrids.