Ramp Slope Research Articles

Toward A Comprehensive Framework for Accessibility Measures for Movement-Challenged Persons

Access is one of the most important rights for persons with disabilities (PWDs), particularly for movement-challenged persons (MCPs). To adopt appropriate policy measures that ensure this right for MCPs, it is necessary to evaluate accessibility appropriately. There are, however, very few accessibility measures applicable to MCPs. The current study proposes a framework for a novel comprehensive accessibility measure for MCPs (CAMMCP) by integrating parameters of universal design and the impact of mode-specific challenges faced by MCPs with existing accessibility measures following an origin-to-destination approach. The study presents a literature review of existing accessibility measures and suggests approaches to modify measures to suit mobility challenges faced by MCPs. Modified accessibility measures have been integrated with other parameters related to universal design and mode-specific problems. Universal-design-related parameters will include ramp slope and curb cuts, which can be measured through physical survey. Information on the impact of mode-specific challenges to MCP accessibility can be collected through questionnaires and participatory survey methods. The study also suggests approaches to modifying existing accessibility measures that do not differentiate between mobility constraints for MCPs and non-MCPs when evaluating accessibility. CAMMCP will be helpful for transportation policymakers taking the initiative to improve built-environment accessibility for MCPs as well as for evaluating projects through the lens of transport equity. It can be particularly helpful in determining walkability and transit-service accessibility. Hopefully, it will help build better road networks and transportation modes to develop a sustainable and inclusive transportation system.

Atypical holocene ctenomyid rodent burrows related to eolian dune deposits from central Argentina

This contribution aims to interpret the producers and the paleoenvironmental context of Holocene rodent burrows (and associated ichnofossils) from the Late Pleistocene-Holocene Meaucó Formation, central La Pampa Province, Argentina. Fieldwork included a detailed sedimentary logging, a ground penetrating radar survey and documentation of the fossil burrow systems. The Meaucó Formation rest on erosive unconformity over the Upper Miocene-Lower Pliocene Cerro Azul Formation and display a vertical change from eolian dunes that become sparser up section (as imaged by ground penetrating radar) and were capped by a paleosol. The paleosol is covered by recent eolian dune and interdune deposits. The fossil rodent burrows occur up to 1.7 m below the paleosol and share several morphologic features with modern Ctenomyidae burrows, except the high slope of entrance and internal ramps, and the maximum depth of burrows. To explain these differences, it is proposed that the burrows were excavated by ctenomyids in ancient sloping surfaces of eolian dunes, which resulted in increased inclination and apparent maximum depth of the systems. This is an example of influence of environmental conditions on the architecture of rodent burrows, and can be of help when interpreting other similar fossil examples. The paleosol community associated with the fossil vertebrate burrows also included other organisms recorded by their trace fossils: horses (Hippipeda isp.), a scrubby vegetation (rhizoliths), coleoptera or spiders (Skolithos linearis), cicada nymphs (Feoichnus challa) and ants (Daimoniobarax isp.).

Integrator dynamics in the cortico-basal ganglia loop underlie flexible motor timing.

Flexible control of motor timing is crucial for behavior. Before volitional movement begins, the frontal cortex and striatum exhibit ramping spiking activity, with variable ramp slopes anticipating movement onsets. This activity in the cortico-basal ganglia loop may function as an adjustable 'timer,' triggering actions at the desired timing. However, because the frontal cortex and striatum share similar ramping dynamics and are both necessary for timing behaviors, distinguishing their individual roles in this timer function remains challenging. To address this, we conducted perturbation experiments combined with multi-regional electrophysiology in mice performing a flexible lick-timing task. Following transient silencing of the frontal cortex, cortical and striatal activity swiftly returned to pre-silencing levels and resumed ramping, leading to a shift in lick timing close to the silencing duration. Conversely, briefly inhibiting the striatum caused a gradual decrease in ramping activity in both regions, with ramping resuming from post-inhibition levels, shifting lick timing beyond the inhibition duration. Thus, inhibiting the frontal cortex and striatum effectively paused and rewound the timer, respectively. These findings suggest the striatum is a part of the network that temporally integrates input from the frontal cortex and generates ramping activity that regulates motor timing.

Simulation of loading and unloading through ramps of different configuration: effects on the ease of handling and physiological response of pigs of two slaughter weights

Behaviour, heart rate (HR) and blood lactate concentration of 144 pigs, equally distributed into lighter (L, 122 kg on average) and heavier (H, 153 kg on average) groups, were assessed to study the effects of slaughter weight on pigs’ response to a simulated loading and unloading procedure using four ramp configurations, i.e., 0º (level ramp), 15º slope and 1.66 m length, 15º slope and 2.71 m length (15ºLO), and 25º slope and 1.66 m. No interaction was found between ramp configuration and slaughter weight (P > 0.10). The frequencies of pigs’ slips or falls (P = 0.01) increased on sloped ramps compared to the floor level (Padj < 0.05), and pigs jumped-off more from the 25° than the 15°LO ramp (Padj = 0.05). Pigs negotiating the 25° slope ramp presented a higher concentration of blood lactate than those walking at the floor level (P = 0.02). When compared to L pigs, H pigs were more reluctant to move (P = 0.05) and, presented higher increments of HR (ΔHR) during handling (P = 0.03). In conclusion, heavier pigs were more difficult to handle, regardless of the ramp steepness, which alone reduced ease of handling and affected the physiological condition of pigs.

Depositional processes in a shale-dominated Devonian succession: Sedimentary facies and trace fossil integrated analysis

Fine-grained rocks have historically been interpreted as a product of the settling of fine fractions in low-energy environments. However, recent studies have suggested that in these environments, more dynamic and complex processes operate. These processes involve a much more diverse set of sedimentary processes than those previously assumed. The lithological homogeneity of clayey successions, associated with the obliteration of their primary characteristics by diagenetic and/or weathering processes, makes it difficult to interpret depositional processes and understand the paleoenvironment. To contribute to a better comprehension of the mechanisms of transport and deposition of fine-grained rocks in a siliciclastic mud-dominated succession, as well as their depositional site, the present study aims at the detailed analysis of a continuous drill core. This core contains a thick Devonian succession consisting essentially of shale from the Ponta Grossa Formation (Paraná Basin, Brazil). Throughout the analyzed succession, a wide variety of sedimentary structures have been identified, such as parallel laminations, wave-ripple cross-stratification, hummocky cross-stratification, normal grading, and gutter casts. These structures show the constant performance of high-energy flows, which are configured as important deposition and/or rework agents. The integrated analysis of facies and trace fossils has proven to be more efficient for paleoenvironmental characterization than isolated approaches. This is because facies and ichnofacies (e.g., Cruziana, with its proximal, impoverished, archetypal, and distal expressions; Skolithos and Glossifungites) can be easily correlated, facilitating the identification of facies associations. This approach not only allows for the interpretation of a shallow marine platform with a gentle slope (ramp shelf) paleoenvironment of moderate to high energy, subject to storm wave action, but also enables the identification of the particular characteristics of deposits from different sub-environments (proximal to distal offshore, offshore transition, shoreface to offshore transition, and prodelta) and their deposition mechanisms. Furthermore, the facies associations are useful for highlighting the variations formed in response to oscillations of the relative sea level and changes in sedimentary input.

Steep medial posterior tibial slope angle and ramp lesion are independent risk factors for an increase in quantitatively measured pivot shift in patients with ACL-deficient knees.

Delayed anterior cruciate ligament (ACL) reconstruction often causes residual anterolateral rotatory instability (ALRI) and consequent knee osteoarthritis, warranting the recommendation of early ACL reconstruction within 6 months after injury. Nonetheless, some cases show notable instability, even shortly after injury. The purpose of this study was to identify risk factors for an increase in quantitatively measured pivot shift in patients with ACL-deficient knees within 6 months after injury. Patients with primary ACL reconstruction within 6 months after injury and quantitative triaxial accelerometer measurements of preoperative pivot shift were included. Descriptive statistics were calculated for 11 independent variables (age, gender, time from injury to surgery, KT-1000, knee extension angle, lateral and medial posterior tibial slope angle, medial and lateral meniscus tears, ramp lesion and Tegner active scale). A single regression analysis was performed on the 11 items and acceleration during the pivot shift, and a multiple regression analysis was performed for items with p value less than 0.1. Overall, 111 patients met the inclusion criteria. Single regression analysis showed that medial posterior tibial slope angle, medial meniscus tear and ramp lesion were significantly correlated with acceleration during the pivot shift (p < 0.001, p = 0.04 and p = 0.001). Multiple regression analysis identified medial posterior tibial slope angles and ramp lesions as independent factors for increased preoperative pivot shift (p = 0.005 and 0.01). A steep medial posterior tibial slope angle and ramp lesion were independent risk factors for increased quantitatively measured pivot shift in patients with ACL-deficient knees. Level IV, case series study.

Investigating Fire–Atmosphere Interaction in a Forest Canopy Using Wavelets

Wildland fire–atmosphere interaction generates complex turbulence patterns, organized across multiple scales, which inform fire-spread behaviour, firebrand transport, and smoke dispersion. Here, we utilize wavelet-based techniques to explore the characteristic temporal scales associated with coherent patterns in the measured temperature and the turbulent fluxes during a prescribed wind-driven (heading) surface fire beneath a forest canopy. We use temperature and velocity measurements from tower-mounted sonic anemometers at multiple heights. Patterns in the wavelet-based energy density of the measured temperature plotted on a time–frequency plane indicate the presence of fire-modulated ramp–cliff structures in the low-to-mid-frequency band (0.01–0.33 Hz), with mean ramp durations approximately 20% shorter and ramp slopes that are an order of magnitude higher compared to no-fire conditions. We then investigate heat- and momentum-flux events near the canopy top through a cross-wavelet coherence analysis. Briefly before the fire-front arrives at the tower base, momentum-flux events are relatively suppressed and turbulent fluxes are chiefly thermally-driven near the canopy top, owing to the tilting of the flame in the direction of the wind. Fire-induced heat-flux events comprising warm updrafts and cool downdrafts are coherent down to periods of a second, whereas ambient heat-flux events operate mainly at higher periods (above 17 s). Later, when the strongest temperature fluctuations are recorded near the surface, fire-induced heat-flux events occur intermittently at shorter scales and cool sweeps start being seen for periods ranging from 8 to 35 s near the canopy top, suggesting a diminishing influence of the flame and increasing background atmospheric variability thereat. The improved understanding of the characteristic time scales associated with fire-induced turbulence features, as the fire-front evolves, will help develop more reliable fire behaviour and scalar transport models.

Effects of ramp slope and substrate type on the climbing success of Pelophylax nigromaculatus in agricultural landscapes

Habitat fragmentation has become a serious threat to amphibian populations worldwide. Concrete anti-seepage, widely applied in waterway construction, has posed a threat by causing amphibians to easily fall into concrete irrigation channels and struggle to escape. However, our understanding of the impact of irrigation channels on frog movement and survival remains limited. In this study, we evaluated the effects of concrete-lined irrigation channels on the escape ability of a common Chinese frog (Pelophylax nigromaculatus). We also analyzed the correlation between the morphology and locomotion ability of the frogs, tested the impact of irrigation channel slope gradient and substrate material on their escape ability, and proposed an optimized design for frog ramps to assist trapped frogs in escaping. The results showed that the frogs have easily fallen into these channels and encountered difficulties in escaping during field activities. As body size was positively related to the frogs’ ability to climb the slope of irrigation channels, the design parameters of the frog ramps should focus on the movement ability of the frogs. The maximum climbing gradients for most frogs on concrete, reverse slope (the protruding structure is placed in the opposite direction of the channel slope), grass and crushed stone are 40°, 50°, 60° and 65°, respectively. Based on experimental tests of the ability of the frogs to climb on various slopes and substrates, we suggest that the slope gradient of concrete irrigation channels should be less than 40°. The findings offer references for scholars and engineers to improve ecological engineering designs of irrigation channels throughout the world.

Brickwall in rotating BTZ: a dip-ramp-plateau story

In this article, building on our recent investigations and motivated by the fuzzball-paradigm, we explore normal modes of a probe massless scalar field in the rotating BTZ-geometry in an asymptotically AdS spacetime and correspondingly obtain the Spectral Form Factor (SFF) of the scalar field. In particular, we analyze the SFF obtained from the single-particle partition function. We observe that, a non-trivial Dip-Ramp-Plateau (DRP) structure, with a Ramp of slope one (within numerical precision) exists in the SFF which is obtained from the grand-canonical partition function. This behaviour is observed to remain stable close to extremality as well. However, at exact extremality, we observe a loss of the DRP-structure in the corresponding SFF. Technically, we have used two methods to obtain our results: (i) An explicit and direct numerical solution of the boundary conditions to obtain the normal modes, (ii) A WKB-approximation, which yields analytic, semi-analytic and efficient numerical solutions for the modes in various regimes. We further re-visit the non-rotating case and elucidate the effectiveness of the WKB-approximation in this case, which allows for an analytic expression of the normal modes in the regime where a level-repulsion exists. This regime corresponds to the lower end of the spectrum as a function of the scalar angular momentum, while the higher end of this spectrum tends to become flat. By analyzing the classical stress-tensor of the probe sector, we further demonstrate that the back-reaction of the scalar field grows fast as the angular momenta of the scalar modes increase in the large angular momenta regime, while the back-reaction remains controllably small in the regime where the spectrum has non-trivial level correlations. This further justifies cutting the spectrum off at a suitable value of the scalar angular momenta, beyond which the scalar back-reaction significantly modifies the background geometry.

Evaluating the Temperature Profile in a Branched Tunnel Fire with Various Ramp Slopes: An Experimental Study

ABSTRACT This study conduct a set of small-scale experiments to examine the combined impact of ramp slopes and bifurcation angles on the longitudinal temperature profile beneath the ceiling of a model of branched tunnel. A Liquefied Petroleum Gas (LPG) fire was used to simulated car fires. The range of heat release rates for the experiments was 2.57 kW to 7.70 kW. The experiments also encompassed three bifurcation angles (5° to 15°) and five ramp slopes (0%, 3%, 5%, 7%, and 9%). A simple model was developed to analyze the steady fire-produced ceiling jet in the branched tunnel. It has been found that the longitudinal temperature decay was not affected by the ramp slopes and bifurcation angles. However, the longitudinal temperature decay varied across different tunnel regions due to the dimensions of the tunnel cross section and the branched structure resulting in smoke divergence flow. In addition, the study established a modified model of longitudinal temperature decay based on the experimental results. The results could be used as a point of reference in developing smoke extraction tactics for branched tunnels.

Effects of ramp slope and discharge on hydraulic performance of submerged hump weirs

Hump weirs are amongst conventional hydraulic structures for water level control and discharge measurement. The slope in the upstream and downstream ramps is a design parameter that affects the performance of Hump weirs in both free and submerged flow conditions. A series of numerical simulations was performed to investigate the effects of ramp slope and discharge on discharge characteristics and water level variations of submerged Hump weirs. Five ramp slopes ranging from 1V:1H to 1V:5H were tested at different upstream discharges. The numerical results were compared with the laboratory data for verifications of the numerical model. The simulation discrepancies in prediction of water surface level and discharge coefficient were within ±10 % and ±5 % of the full range, respectively. The effects of ramp slope on variations of modular limit and discharge reduction factor were studied. It was found that the modular limit occurred at relatively higher submergence ratios as the ramp slope in Hump weirs increased. The onset of submergence was modeled by carefully increasing tailwater level with small increments and the results were compared with the classic definition of modular limit. It was found that the modular limit increases with increasing the ramp slope and discharge while the classic definition of modular limit indicated that the modular limit is independent of the discharge. The velocity and vortex fields in the downstream of Hump weirs indicated the formation vortex structure, which is controlled by the ramp slope. The energy losses were calculated from the numerical outputs, and it was found that the normalized energy losses decreased linearly with submergence.

Apron and macro roughness as scour countermeasures downstream of block ramps

ABSTRACT A block ramp is a grade-control structure commonly used to stabilize the river bed with a high efficiency of energy dissipation. This study investigates the effects of using macro roughness and a downstream apron as scour countermeasures on the maximum scour depth downstream of block ramps in straight rivers. All the experiments have been carried out in a horizontal channel and in clear water conditions (no sediment transport). A wide range of hydraulic conditions including densimetric Froude numbers, water drop heights, and tailwater depths for three different rough ramp slopes (1 V:3 H, 1 V:5 H, and 1 V:7 H) was tested. The results have been compared with the results from a smooth ramp (no roughness), which has been considered as a reference. Results show that both macro roughness on the ramp and downstream aprons work well as scour countermeasures while as a comparison, using macro roughness (big-size stones) on the ramp is more effective than downstream aprons to reduce the scour depth. The other finding of this study shows that increasing the downstream apron decreases the length of the scour hole, consequently decreasing the volume of eroded material.

Complaint constant force mechanism using variable stiffness leaf-spring-like beam: Design and experiment

&lt;p style='text-indent:20px;'&gt;This research provides a design for a complaint constant-force mechanism employing a leaf-spring-like beam with variable stiffness to address the negative stiffness stroke underutilization issue of the bistable beam. By designing the compression of the leaf-spring-like beam at each given displacement and the compression ramp slope, this technique allows the constant force mechanism to potentially take full utilization of the bistable beam's negative stiffness component. Innovative design of a complaint constant force mechanism based on positive and negative stiffness is shown in this study. In addition, we conduct simulation analysis and experimental verification. The experimental results illustrate the feasibility and effectiveness of the proposed method.&lt;/p&gt;

Evaluation of the "Step-Ramp-Step" Protocol: Accurate Aerobic Exercise Prescription with Different Steps and Ramp Slopes.

To assess whether: i) a lower amplitude constant-load MOD is appropriate to determine the mean response time (MRT); ii) the method accurately corrects the dissociation in the V̇O 2 -PO relationship during ramp compared with constant-load exercise when using different ramp slopes. Eighteen participants (7 females) performed three SRS tests including: i) step-transitions into MOD from 20 to 50 W (MOD 50 ) and 80 W (MOD 80 ); and ii) slopes of 15, 30, and 45 W·min -1 . The V̇O 2 and PO at the gas exchange threshold (GET) and the corrected respiratory compensation point (RCP CORR ) were determined. Two to three 30-min constant-load trials evaluated the V̇O 2 and PO at the maximal metabolic steady state (MMSS). There were no differences in V̇O 2 at GET (1.97 ± 0.36, 1.99 ± 0.36, 1.95 ± 0.30 L·min -1 ), and RCP (2.81 ± 0.57, 2.86 ± 0.59, 2.84 ± 0.59) between 15, 30, and 45 W·min -1 ramps, respectively ( P > 0.05). The MRT in seconds was not affected by the amplitude of the MOD or the slope of the ramp (range 19 ± 10 s to 23 ± 20 s; P > 0.05). The mean PO at GET was not significantly affected by the amplitude of the MOD or the slope of the ramp (range 130 ± 30 W to 137 ± 30 W; P > 0.05). The PO at RCP CORR was similar for all conditions ((range 186 ± 43 W to 193 ± 47 W; P > 0.05). The SRS protocol accounts for the V̇O 2 MRT when using smaller amplitude steps, and for the V̇O 2 slow component when using different ramp slopes, allowing for accurate partitioning of the exercise intensity domains in a single test.

A new method for finding the proper initial conditions in passive locomotion of bipedal robotic systems

In this paper, the walking motion of a biped robot consisting of upper and lower body members (arms, legs, upper trunk and neck) on an inclined surface is analyzed kinematically and dynamically. Some of the challenges faced by this research include the dual-phase dynamics that govern the periodic gait of this robotic system and the consideration of all the body parts that are involved in the walking motion; which make it extremely difficult to derive the kinetic equations of such robotic systems. To deal with these challenges, the Gibbs-Appell formulation and the Newton's impact laws are employed to derive the most general form of the system's dynamic equations in the swing and transient phases of motion. Subsequently, by using the obtained motion equations and implementing a systematic procedure, we achieve an eigenvalue problem. By solving this problem, the suitable initial conditions that are necessary for the passive gait of this biped robot on a sloping surface are determined. By considering the obtained initial conditions as well as the dynamic response of the system to the Earth's gravity, we describe a general method for designing a biped robot's walking trajectory on an inclined surface. The most important feature of the designed trajectory is its close agreement with the trajectory followed by a biped robot walking passively down a sloping ramp. This close match between the said trajectories enables us to guide the robot in tracking a desired path by applying very small control torques to the robot joints at the start of each step. This claim is corroborated by the simulations carried out for a biped walking robot composed of 6 rigid links, in which the control torques that are applied to the actuated robot joints are obtained by employing a feedback linearization method and via a designed LQR controller.

Implementation of Padang City Regional Regulation Number 3 of 2015 on Accessibility of The Trans Padang

Padang is one of the cities that upholds the rights of persons who have disabilities. With the existence of regional regulation number 3 of 2015. The performance of the Padang Regional Regulation No. 3 of 2015 concerning the Fulfillment and Protection of the Rights of Persons who have Disabilities has not been fully implemented. Judging from the accessibility of the Trans Padang public transportation sector, there are still many bus station buildings that do not yet support disabled passengers to carry out their activities independently. PT. Padang Sejahtera Mandiri as the BUMD that operates Trans Padang needs to evaluate the accessibility in corridor 1. From the survey results, it was found that many bus station buildings do not provide facilities for people with disabilities. The purpose of this study was to evaluate accessibility at the Trans Padang bus stop in order to optimize the application of local regulations regarding persons with disabilities. The author uses a descriptive qualitative research method. The study was conducted by surveying the Trans Padang bus station along Corridor I and then comparing the existing condition of the survey results with existing standards. Based on the analysis, it was found that many bus stations did not meet the requirements. The only facilities available are guiding blocks and ramps. For guiding blocks, there are only 12 bus station buildings. As for the slope of the appropriate ramp, there are only 5 bus station buildings.

Study with Large Eddy Simulations of energy dissipation due to backwash flows in wave overtopping.

Renewable energy market growth is imperative to reach a sustainable society. This necessity demands improving existing methodologies to exploit green energy sources and explore new technologies. Wave energy is one of the sources with the larger offer in power available in the oceans to be harvested; however, the remoteness and extreme conditions of the best locations to harvest wave energy have made the development of wave energy converters expensive and less attractive than other green energy sources that operate on land. Overtopping wave energy converters (OWEC) operate on the shore, facilitating their construction and maintenance. They can be integrated into coastal defences, sharing the cost of construction and their environmental impact and creating new benefits from the coastal defence. The effectiveness of an OWEC relies strongly on their ability to capture wave-overtopping volumes. The geometry of the run-up ramp (slope and shape) plays an important role in the efficiency of an OWEC. An optimum geometry for each location and wave condition needs to be found to maximise the operation of any OWEC. The efficiency of these devices, quantified by the hydraulic efficiency, must be improved to make them an attractive solution for energy conversion. Three distinguishable processes occurred on the ramp of an OWEC; the wave collapse, run-up and run-down (backwash). The first two have attracted more attention from researchers, specially oriented to the design of coastal defences, but fewer studies have analysed the impact of the backwash on the energy losses during the collapse of the waves. When an incoming wave approaches the run-up ramp, it crashes against the backwash, composed of the water volume that didn't overtop the structure in the previous wave. These interactions increase turbulences and, therefore, energy dissipation, affecting the performance of an OWEC. This study analyses the hydrodynamics during the backwash flows' and incoming waves' interaction on sloped structures. A numerical code Hydro3D, based on Large Eddy Simulations, is used to conduct the present study. As a reference condition, a structure with a freeboard high enough to not allow wave overtopping is tested; in this case, all the water that run-up the slope runs down after the water tongue reaches its highest elevation. Structures with lower freeboards are tested to allow different wave overtopping levels and backwash flows. The impact of different backwash flow conditions on energy dissipation is then evaluated. The founding of this study allows us to verify if a reduction in the backwash flows can improve the efficiency of a OWEC.

Effect of ramp slope on intensity thresholds based on correlation properties of heart rate variability during cycling.

An index of heart rate variability (HRV), detrended fluctuation analysis (DFA a1) has gathered interest as a surrogate marker of exercise intensity boundaries. The aim of this report was to examine heart rate variability threshold (HRVT) behavior across different ramp incremental (RI) slopes. Seventeen participants completed a series of three RI (15, 30, and 45 W · min-1 slopes) with monitoring of gas exchange parameters, heart rate (HR) and HRV. HRVT1 was defined as the V̇O2 or HR at which DFA a1 reached 0.75 and the HRVT2 at which these values reached 0.5. HRVTs were compared by Pearson's r, Bland-Altman analysis, ICC3,1 , ANOVA, and paired t-testing. An excellent degree of reliability was seen across all three ramps, with an ICC3,1 of 0.93 and 0.88 for the HRVT1 V̇O2 and HR, respectively, and 0.90 and 0.92 for the HRVT2 V̇O2 and HR, respectively. Correlations between HRVT1/2 of the individual ramps were high with r values 0.84-0.95 for both HR and V̇O2 . Bland-Altman differences ranged between -1.4 and 1.2 mL · kg-1 · min-1 and -2 and +2 bpm. Paired t-testing showed no mean differences between any HRVT1/2 ramp comparisons. Cycling ramp slope does not appear to affect either HRVT1 or HRVT2 in terms of HR or V̇O2 .

A 1/f noise optimized correlated multiple sampling technique for complementary metal oxide semiconductor image sensor

SummaryCorrelated multiple sampling (CMS) technique is often used to reduce random noise in complementary metal oxide semiconductor (CMOS) image sensor, but as the number of samples increases, the suppression of 1/f noise by standard CMS based on averaging sampling gradually decreases. Therefore, in this paper, a 1/f noise optimized correlated multiple sampling (NOCMS) technique based on differentiated sampling weights is proposed. Transfer functions of standard CMS and NOCMS for analyzing the suppression effect of random noise respectively are derived based on the Fourier transform theory. And NOCMS shows a dramatic advantage in the suppression of 1/f noise. In addition, a circuit structure based on single‐slope analog‐to‐digital converter (SSADC) for implementing NOCMS is suggested. Ramp generator provides multiple sets of ramps with different slopes to quantify the reset and signal voltages of pixel output. Sampling weights are increased with the decrease of ramp slopes. The last reset and first signal values are weighted more due to their potentially higher correlations which highlights the principle of assigning weights. Simulation results under 110 nm CMOS technology illustrate that the input‐referred random noise is 142.9 V under standard CMS and 120.9 V under NOCMS when the number of samples equals 8. The noise reduction effect is improved by 15%. NOCMS makes it possible to further reduce 1/f noise of CMOS image sensor.

Microcontroller-Based Trapezoidal Slope Compensation Technique for Peak Current Mode Control at MHz Frequencies

Slope compensation is necessary for the peak cur-rent mode control technique to ensure the stability of the power converter. Micro-controllers (μCs) existing in the market implement the slope compensation using built-in digital to analog converters (DACs). DACs exhibit finite transient times, which can be negligible when the μCs are used to control the power converters at switching frequencies in the order of a few hundreds of kHz. However, for high device switching frequency (HDSF) operation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\geq 1\, \rm{MHz}$</tex-math></inline-formula> ), the DAC transient time becomes significant and can make it difficult, if not impossible, to achieve the conventional ramp slope compensation. Hence, in this paper, a novel concept of ‘trapezoidal’ slope compensation is proposed by considering the transient time of the μC. A detailed analysis is performed to understand the effect of the transient period on the converter stability. The proposed technique is validated with an experimental prototype of 400 W at 1 MHz switching frequency and it is shown to ensure stability of the converter at all operating points within the specification.