Academic literature on the topic 'Ramp function regression'
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Journal articles on the topic "Ramp function regression"
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Mudelsee, Manfred. "Ramp function regression: a tool for quantifying climate transitions." Computers & Geosciences 26, no. 3 (2000): 293–307. http://dx.doi.org/10.1016/s0098-3004(99)00141-7.
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Zhang, Cuiqing, Maojun Zhang, Xijun Liang, Zhonghang Xia, and Jiangxia Nan. "Perceptron Ranking Using Interval Labels with Ramp Loss for Online Ordinal Regression." Mathematical Problems in Engineering 2020 (December 2, 2020): 1–15. http://dx.doi.org/10.1155/2020/8866257.
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Due to its wide applications and learning efficiency, online ordinal regression using perceptron algorithms with interval labels (PRIL) has been increasingly applied to solve ordinal ranking problems. However, it is still a challenge for the PRIL method to handle noise labels, in which case the ranking results may change dramatically. To tackle this problem, in this paper, we propose noise-resilient online learning algorithms using ramp loss function, called PRIL-RAMP, and its nonlinear variant K-PRIL-RAMP, to improve the performance of PRIL method for noisy data streams. The proposed algorithms iteratively optimize the decision function under the framework of online gradient descent (OGD), and we justify the algorithms by showing the order preservation of thresholds. It is validated in the experiments that both approaches are more robust and efficient to noise labels than state-of-the-art online ordinal regression algorithms on real-world datasets.
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Shea, M. Scott, Thanh Q. Le, and Richard J. Porter. "Combined Crash Frequency–Crash Severity Evaluation of Geometric Design Decisions." Transportation Research Record: Journal of the Transportation Research Board 2521, no. 1 (2015): 54–63. http://dx.doi.org/10.3141/2521-06.
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This paper quantified the effects of freeway ramp spacing and auxiliary lane presence on crash frequency and crash severity. Crash frequencies were predicted with a safety performance function, and crash severities were estimated with what was termed a “severity distribution function.” The paper then demonstrated how to combine quantitative knowledge related to the effects of ramp spacing and auxiliary lane presence on both crash frequency and severity into a framework for assessing the overall crash cost for different ramp configurations. Geometric features, traffic characteristics, and crash data were collected for 404 freeway segments in California and Washington State. Negative binomial regression models and multinomial logit regression models were used to estimate the effects of ramp spacing and auxiliary lane presence on expected crash frequencies and crash severities, respectively. Results showed that expected multiple-vehicle crash frequency increased as ramp spacing decreased. Meanwhile, there was a decrease in the proportion of severe crashes (fatal, incapacitating injury) with a decrease in ramp spacing, even though the overall frequency of these severe crashes remained relatively unchanged. Providing an auxiliary lane was expected to decrease crash frequency, although this reduction appeared to be primarily in crashes that were less severe (possible injury and property damage only). The findings appeared to effectively capture the complex relationships between geometric designs and operations and the high sensitivity between speed and crash severity. The paper provided quantitative tools for making informed freeway and interchange design decisions where ramp spacing and auxiliary lanes were considerations.
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Sun, Jian, Kang Zuo, Shun Jiang, and Zuduo Zheng. "Modeling and Predicting Stochastic Merging Behaviors at Freeway On-Ramp Bottlenecks." Journal of Advanced Transportation 2018 (2018): 1–15. http://dx.doi.org/10.1155/2018/9308580.
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Merging behavior is inevitable at on-ramp bottlenecks and is a significant factor in triggering traffic breakdown. In modeling merging behaviors, the gap acceptance theory is generally used. Gap acceptance theory holds that when a gap is larger than the critical gap, the vehicle will merge into the mainline. In this study, however, analyses not only focus on the accepted gaps, but also take the rejected gaps into account, and the impact on merging behavior with multi-rejected (more than once rejecting behavior) gaps was investigated; it shows that the multi-rejected gaps have a great influence on the estimation of critical gap and merging prediction. Two empirical trajectory data sets were collected and analyzed: one at Yan’an Expressway in Shanghai, China, and the other at Highway 101 in Los Angeles, USA. The study made three main contributions. First, it gives the quantitative measurement of the rejected gap which is also a detailed description of non-merging event and investigated the characteristics of the multi-rejected gaps; second, taking the multi-rejected gaps into consideration, it further expanded the concept of the “critical gap” which can be a statistic one and the distribution function of merging probability with respect to such gaps was analyzed by means of survival analysis. This way could make the full use of multi-rejected gaps and accepted gaps and reduce the sample bias, thus estimating the critical gap accurately; finally, considering multi-rejected gaps, it created logistic regression models to predict merging behavior. These models were tested using field data, and satisfactory performances were obtained.
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Abramowitch, Steven D., and Savio L. Y. Woo. "An Improved Method to Analyze the Stress Relaxation of Ligaments Following a Finite Ramp Time Based on the Quasi-Linear Viscoelastic Theory." Journal of Biomechanical Engineering 126, no. 1 (2004): 92–97. http://dx.doi.org/10.1115/1.1645528.
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The quasi-linear viscoelastic (QLV) theory proposed by Fung (1972) has been frequently used to model the nonlinear time- and history-dependent viscoelastic behavior of many soft tissues. It is common to use five constants to describe the instantaneous elastic response (constants A and B) and reduced relaxation function (constants C, τ1, and τ2) on experiments with finite ramp times followed by stress relaxation to equilibrium. However, a limitation is that the theory is based on a step change in strain which is not possible to perform experimentally. Accounting for this limitation may result in regression algorithms that converge poorly and yield nonunique solutions with highly variable constants, especially for long ramp times (Kwan et al. 1993). The goal of the present study was to introduce an improved approach to obtain the constants for QLV theory that converges to a unique solution with minimal variability. Six goat femur-medial collateral ligament-tibia complexes were subjected to a uniaxial tension test (ramp time of 18.4 s) followed by one hour of stress relaxation. The convoluted QLV constitutive equation was simultaneously curve-fit to the ramping and relaxation portions of the data r2>0.99. Confidence intervals of the constants were generated from a bootstrapping analysis and revealed that constants were distributed within 1% of their median values. For validation, the determined constants were used to predict peak stresses from a separate cyclic stress relaxation test with averaged errors across all specimens measuring less than 6.3±6.0% of the experimental values. For comparison, an analysis that assumed an instantaneous ramp time was also performed and the constants obtained for the two approaches were compared. Significant differences were observed for constants B, C, τ1, and τ2, with τ1 differing by an order of magnitude. By taking into account the ramping phase of the experiment, the approach allows for viscoelastic properties to be determined independent of the strain rate applied. Thus, the results obtained from different laboratories and from different tissues may be compared.
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Chapple, W. D. "Mechanics of stretch in activated crustacean slow muscle. II. Dynamic changes in force in response to stretch." Journal of Neurophysiology 62, no. 5 (1989): 1006–17. http://dx.doi.org/10.1152/jn.1989.62.5.1006.
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1. The mechanical dynamics of the ventral superficial muscles (VSM) of the abdomen of the hermit crab, Pagurus pollicarus, have been analyzed to develop a quantitative model of gradedly excitable arthropod muscle. Such a model is important for understanding the role of proprioceptive reflexes in posture and movement. 2. The decay in force produced after ramp stretch of both passive and active muscle was approximated by the use of regression equations involving a direct term and one to three exponential terms. A second-order equation produced an acceptable description of this decay over short (0.5 s) sampling durations. 3. The rate constants of the regression equation did not vary with stretch length, velocity, or activation level of the muscle. For the two-exponential-term model, the rate constants were approximately 90 and 9 s-1 for a sample duration of 0.3 s. An additional rate constant of approximately 1 s-1 was needed to adapt the model to longer sample times. 4. The direct term and the middle-order (9 s-1) residual were both functions of stretch length and activation level. The high-order (90 s-1) residual was primarily a function of stretch length and velocity. Transfer functions omitting the velocity dependence adequately described the mechanical dynamics of the muscle for physiological ranges of stretch velocity. 5. White-noise length perturbations were used to calculate spectral density functions of muscle force and length. These measurements confirmed the principal observations of the ramp stretch analysis: the frequency response of the muscle was independent of the level of activation; the magnitude of the stiffness increased over the stretch frequency range of 4-40 Hz and was then almost constant; and the phase response of the muscle became slightly positive over the same range of stretch frequency. 6. The speed of activation of the muscle to different stimulus frequencies was estimated by fitting a single exponential equation to the rise in isometric tension at the onset of stimulation of the motor nerve. The rate constant increased with stimulus frequency, but its maximum value was only 1.8 s-1, about one-fourth of the middle mechanical rate constant. 7. Because muscle activation is slower than the mechanical dynamics, it is unlikely that the nervous system can regulate muscle dynamics. However, it is possible that mechanical impedance could be regulated to maintain a desired time-averaged value.
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Fawkner, Samantha G., Neil Armstrong, David J. Childs, and Joanne R. Welsman. "Reliability of the Visually Identified Ventilatory Threshold and V-Slope in Children." Pediatric Exercise Science 14, no. 2 (2002): 181–92. http://dx.doi.org/10.1123/pes.14.2.181.
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The purpose of this study was to assess the reliability of the ventilatory threshold using visual analysis (TVent) and a computerised v-slope method (TV - slope) with children. Twenty-two children completed 2 ramp incremental cycling tests to voluntary exhaustion. Oxygen uptake (V̇O2) at TVent was derived independently by two observers using plots of V̇E/V̇CO2, V̇E/V̇O2, PETO2 and PETCO2, V̇E and RER as a function of time. V̇O2 at TV - slope was determined by both observers using linear regression analysis of the plot of V̇CO2 against V̇O2. A TV – slope was determined for each test, although a TVent could not be found by one of the observers in 7 of the 44 tests. Inter-observer reliability was slightly better for TV - slope, and both methods had similar test-retest coefficients of repeatability (0.19 and 0.22 L • min−1, TVent and TV - slope, respectively). Although TV slope may be the method of choice, investigators should consider the 95% limits of agreement when interpreting their data.
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Stringer, William W., James E. Hansen, and K. Wasserman. "Cardiac output estimated noninvasively from oxygen uptake during exercise." Journal of Applied Physiology 82, no. 3 (1997): 908–12. http://dx.doi.org/10.1152/jappl.1997.82.3.908.
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Stringer, William W., James E. Hansen, and K. Wasserman.Cardiac output estimated noninvasively from oxygen uptake during exercise. J. Appl. Physiol. 82(3): 908–912, 1997.—Because gas-exchange measurements during cardiopulmonary exercise testing allow noninvasive measurement of oxygen uptake (V˙o 2), which is equal to cardiac output (CO) × arteriovenous oxygen content difference [C(a-[Formula: see text])], CO and stroke volume could theoretically be estimated if the C(a-[Formula: see text]) increased in a predictable fashion as a function of %maximumV˙o 2(V˙o 2 max) during exercise. To investigate the behavior of C(a-[Formula: see text]) during progressively increasing ramp pattern cycle ergometry exercise, 5 healthy subjects performed 10 studies to exhaustion while arterial and mixed venous blood were sampled. Samples were analyzed for blood gases (pH, [Formula: see text],[Formula: see text]) and oxyhemoglobin and hemoglobin concentration with a CO-oximeter. The C(a-[Formula: see text]) (ml/100 ml) could be estimated with a linear regression [C(a-[Formula: see text]) = 5.72 + 0.105 × %V˙o 2 max; r = 0.94]. The CO estimated from the C(a-[Formula: see text]) by using the above linear regression was well correlated with the CO determined by the direct Fick method ( r = 0.96). The coefficient of variation of the estimated CO was small (7–9%) between the lactic acidosis threshold and peakV˙o 2. The behavior of C(a-[Formula: see text]), as related to peakV˙o 2, was similar regardless of cardiac function compared with similar measurements from studies in the literature performed in normal and congestive heart failure patients. In summary, CO and stroke volume can be estimated during progressive work rate exercise testing from measuredV˙o 2 (in normal subjects and patients with congestive heart failure), and the resultant linear regression equation provides a good estimate of C(a-[Formula: see text]).
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Lai, Nicola, Justin J. Fiutem, Nora Pfaff, Desy Salvadego, and James Strainic. "Relating cardiorespiratory responses to work rate during incremental ramp exercise on treadmill in children and adolescents: sex and age differences." European Journal of Applied Physiology 121, no. 10 (2021): 2731–41. http://dx.doi.org/10.1007/s00421-021-04741-1.
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Abstract Purpose Evaluation of cardiopulmonary exercise testing (CPET) slopes such as $$d\mathrm{H}\mathrm{R}/d{\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ d H R / d W R t o t (cardiac/skeletal muscle function) and $${d \dot{V}{\text{O}} }_{2}/d{\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ d V ˙ O 2 / d W R t o t (O2 delivery/utilization), using treadmill protocols is limited because the difficulties in measuring the total work rate ($${\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ W R t o t ). To overcome this limitation, we proposed a new method in quantifying $${\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ W R t o t to determine CPET slopes. Methods CPET’s were performed by healthy patients, (n = 674, 9–18 year) 300 female (F) and 374 male (M), using an incremental ramp protocol on a treadmill. For this protocol, a quantitative relationship based on biomechanical principles of human locomotion, was used to quantify the $${\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ W R t o t of the subject. CPET slopes were determined by linear regression of the data recorded until the gas exchange threshold occurred. Results The method to estimate $${\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ W R t o t was substantiated by verifying that: $$d{ \dot{V}{\text{O}} }_{2}/d{\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ d V ˙ O 2 / d W R t o t for treadmill exercise corresponded to an efficiency of muscular work similar to that of cycle ergometer; $$d{ \dot{V}{\text{O}} }_{2}/d{\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ d V ˙ O 2 / d W R t o t (mL min−1 W−1) was invariant with age and greater in M than F older than 12 years old (13–14 years: 9.6 ± 1.5(F) vs. 10.5 ± 1.8(M); 15–16 years: 9.7 ± 1.7(F) vs. 10.6 ± 2.2(M); 17–18 years: 9.6 ± 1.7(F) vs. 11.0 ± 2.3(M), p < 0.05); similar to cycle ergometer exercise, $$dHR/d{WR}_{tot}$$ d H R / d WR tot was inversely related to body weight (BW) (r = 0.71) or $$\dot{V}{\text{O}}_{{2,{\text{~peak}}}}$$ V ˙ O 2 , peak (r = 0.66) and $$d{ \dot{V}{\text{O}} }_{2}/d{\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ d V ˙ O 2 / d W R t o t was not related to BW (r = − 0.01), but had a weak relationship with $$\dot{V}{\text{O}}_{{2,{\text{~peak}}}}$$ V ˙ O 2 , peak (r = 0.28). Conclusion The proposed approach can be used to estimate $${\mathrm{W}\mathrm{R}}_{\mathrm{t}\mathrm{o}\mathrm{t}}$$ W R t o t and quantify CPET slopes derived from incremental ramp protocols at submaximal exercise intensities using the treadmill, like the cycle ergometer, to infer cardiovascular and metabolic function in both healthy and diseased states.
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Bared, Joe G., Alvin Powell, and Evangelos Kaisar. "Traffic Planning Models for Single-Point and Tight Diamond Interchanges." Transportation Research Record: Journal of the Transportation Research Board 1847, no. 1 (2003): 52–57. http://dx.doi.org/10.3141/1847-07.
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Although the single-point interchange (SPI) has been around for approximately three decades, users do not yet have a simplified procedure to evaluate its traffic performance with a similar configuration, the tight diamond interchange (TDI). Several studies have derived general results without decisive conclusions or with partial coverage to assist the users in the selection process. Simulation modeling is used to compare operational traffic performances of isolated SPI and TDI without frontage roads. Modeling was conducted on similar geometries over a wide distribution of traffic flow conditions (101 scenarios). The 101 scenarios were run for both SPI and TDI to derive control delay, stop time, and percent stops from CORSIM. The multivariate statistical comparison of all three variables showed a combined significant difference between the two interchange types, favoring SPI. TDI created more delay, stop time, and percent stops when the left-turn off-ramp flows were very high. Regression models were derived to estimate the three measures for both SPI and TDI. The models are robust and are functions of the highest flows on the cross street and off-ramps. These models are tools that can help planners in the evaluation and selection process of these interchange configurations.
Dissertations / Theses on the topic "Ramp function regression"
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Mudelsee, Manfred. "Rampenregression - Quantifizierung von Temperaturtrends." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-215518.
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Die Jahresmitteltemperatur-Zeitreihen dreier Stationen (Berlin, Leipzig und Stockholm) werden auf ihre langfristigen Trends im Zeitbereich 1830-1980 untersucht. Dazu wird die neuartige, parametrische Methode der Rampenregression (Mudelsee 1999a) verwendet. Die Vorteile gegenüber bisher verwendeten Verfahren sind (1) eine realistischeres Übergangsmodell und (2) Angaben des statistischen Fehlers geschätzter Übergangs-Zeitpunkte und -Niveaus. Leipzig (Erwärmung um 0.86±0.13 °C von 1889±7bis1911±7) und Stockholm (Erwärmung um 1.01±0.22 °C von 1879±23 bis 1945±21) zeigen beide einen rampenförmigen Trendverlauf, Berlin dagegen einen noch komplizierteren Trend. Im Falle von Leipzig liegt wahrscheinlich ein deutlicher Urbanisierungseinfluß vor. Die Rampenregression bietet die Möglichkeit, einen globalen Klimawechsel genauer zu quantifizieren<br>Timeseries of annual average temperature from three stations (Berlin, Leipzig and Stockholm) are investigated with regards to their long-term trends in the time interval 1830-1980. For that, the new, parametric method of ramp function regression (Mudelsee 1999a) is used. The advantages against other previously employed methods are (1) a more realistic transition model and (2) information about the statistical accuracy of estimated transition dates and levels. Both Leipzig (warming by 0.86±0.13 °C, from 1889±7 to 1911±7) and Stockholm (warming by 1.01±0.22 °C, from 1879±23 to 1945±21) show a ramp-form trend, whereas Berlin\'s trend is even more complicated. In the case of Leipzig a significant contribution by urbanization is likely. Ramp function regression has the potential to quantify a global climate change more accurately
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Mudelsee, Manfred. "Rampenregression - Quantifizierung von Temperaturtrends." Wissenschaftliche Mitteilungen des Leipziger Instituts für Meteorologie ; 17 = Meteorologische Arbeiten aus Leipzig ; 5 (2000), S. 148-162, 2000. https://ul.qucosa.de/id/qucosa%3A15161.
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Die Jahresmitteltemperatur-Zeitreihen dreier Stationen (Berlin, Leipzig und Stockholm) werden auf ihre langfristigen Trends im Zeitbereich 1830-1980 untersucht. Dazu wird die neuartige, parametrische Methode der Rampenregression (Mudelsee 1999a) verwendet. Die Vorteile gegenüber bisher verwendeten Verfahren sind (1) eine realistischeres Übergangsmodell und (2) Angaben des statistischen Fehlers geschätzter Übergangs-Zeitpunkte und -Niveaus. Leipzig (Erwärmung um 0.86±0.13 °C von 1889±7bis1911±7) und Stockholm (Erwärmung um 1.01±0.22 °C von 1879±23 bis 1945±21) zeigen beide einen rampenförmigen Trendverlauf, Berlin dagegen einen noch komplizierteren Trend. Im Falle von Leipzig liegt wahrscheinlich ein deutlicher Urbanisierungseinfluß vor. Die Rampenregression bietet die Möglichkeit, einen globalen Klimawechsel genauer zu quantifizieren.<br>Timeseries of annual average temperature from three stations (Berlin, Leipzig and Stockholm) are investigated with regards to their long-term trends in the time interval 1830-1980. For that, the new, parametric method of ramp function regression (Mudelsee 1999a) is used. The advantages against other previously employed methods are (1) a more realistic transition model and (2) information about the statistical accuracy of estimated transition dates and levels. Both Leipzig (warming by 0.86±0.13 °C, from 1889±7 to 1911±7) and Stockholm (warming by 1.01±0.22 °C, from 1879±23 to 1945±21) show a ramp-form trend, whereas Berlin\''s trend is even more complicated. In the case of Leipzig a significant contribution by urbanization is likely. Ramp function regression has the potential to quantify a global climate change more accurately.
Book chapters on the topic "Ramp function regression"
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Speed*, Robert C., and Hai Cheng†. "Marine terrace evolution of windward Barbados." In Emergence and Evolution of Barbados. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2549(01).
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ABSTRACT The geomorphic evolution of southeastern windward Barbados is embodied in the development of a terraced seaward island slope on a tectonically rising scarp. The island slope is wholly erosional and a product of marine and subaerial processes. Modulation of the slope by terraces has occurred fundamentally by marine erosion at eustatic stillstands but includes morphologic additions by limestone deposition. The ongoing phase of morphologic development and island emergence began at or before ca. 700 ka. Emergence has proceeded at an increasing rate northwestward along the island’s southeastern coastline. The terraced island slope is markedly affected by post-terrace denudation. As many as eight marine terraces are preserved on the windward island slope below the planed surface of the Central Highlands, which is counted as terrace 1. Relics of an upper set of terraces are perched on the face of Second High Cliff, the ancient erosional margin of the oldest limestone capping Barbados. Second High Cliff developed by successive marine incisions over a probably long duration preceding oxygen isotope stage 9. A lower terrace set was excised in stages 9 through 5a in the siliciclastic island foundation or (and) in limestone cover of preceding terraces. Marine terrace floors extend seaward from an erosional backcliff and shoreline angle to a younger erosional cutoff. The most broadly preserved terrace floors indicate the following systematic succession of seaward profile elements: narrow upper ramp; broad upper flat; lower ramp; and on one, a lower flat. Carbonate cover is chiefly clastic on the upper ramp and flat, and chiefly reefal on the lower ramp. Most shoal-water reefal facies appear to be in fringe reef blankets. Terrace profile geometries are explained by a simple theory of wave abrasion in proportion to duration of sea level at a shoreline. At stillstands, the wave impact caused large shoreline recession and development of flats, whereas in transgression and regression, rapid sea-level change permitted only minor recession. Corresponding differences in cover facies are explained as functions of duration of breaking waves and seabed stability. Widespread post-terrace denudation is attributed to floods of upland provenance, local overland flow, and marine flooding. Riverine processes have produced channelization and a high degree of terrace preservation on the interfluves in the steeper, foundation-based northern windward region. This differs markedly from the more diffuse, shallow gullying and stripping of the limestone-covered shallow slopes of the southern region. An intensely stormy spell is suggested between stages 5e and 5c.
Conference papers on the topic "Ramp function regression"
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Ma, Xiaoyan, Yanbin Zhang, and Yanxia Wang. "Performance evaluation of kernel functions based on grid search for support vector regression." In 2015 IEEE 7th International Conference on Cybernetics and Intelligent Systems (CIS) and IEEE Conference on Robotics, Automation and Mechatronics (RAM). IEEE, 2015. http://dx.doi.org/10.1109/iccis.2015.7274635.
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