Stopping Behavior Research Articles

A unified model for the simulation of oil, gas and biomass space heating boilers for energy estimating purposes. Part II: Parameterization and comparison with measurements

A semi-physical model for the simulation of oil, gas and biomass space heating boilers has been parameterized based on measurements on nine different boiler units and simulation results have been compared to results obtained from measurements in steady state and transient operation. Although the agreement between simulated and measured boiler efficiencies was within the range of measurement uncertainties in most cases, model improvements are expected to be possible concerning the heat capacitance modelling in cycling on/off operation as well as influences of start and stop behaviour on the overall efficiency. It is found that electricity consumption during cycling on/off operation of small pellets or oil space heating boilers may have a significant influence on the overall energy balance of these units. This influence increases strongly with decreasing heat load and increasing number of on/off cycles.

Snow avalanche flow-regime transitions induced by mass and random kinetic energy fluxes

AbstractWe perform a linear-stability analysis of a system of ordinary differential equations describing the motion of dense flowing avalanches. The depth-averaged equations relate the mean translational velocity of the avalanche to the production of turbulent kinetic energy associated with the random motion of the snow granules. Flow friction is described by an extended Voellmy model, where both the Coulomb and turbulent resistance are related to the random kinetic energy. We identify two snow avalanche flow regimes: (1) an unstable frictional flow regime characterized by low random kinetic energy production and (2) a stable, collisional flow regime at the avalanche front. Flow-regime transitions are governed by the production of random kinetic energy, which is controlled by mass. The unstable regime is characterized by a saddle point which the avalanche encounters at the onset of motion and deposition. Depending on the release mass and/or mass growth, the avalanche head will either fluidize, leading to far-reaching avalanches, or starve and die out. At the tail of the avalanche this saddle point also controls the commencement of deposition and therefore the stopping behaviour of avalanches. We discuss the conditions for flow-regime transitions and the enhanced mobility of snow avalanches.

Glancing and Stopping Behavior of Motorcyclists and Car Drivers at Intersections

For the past decade, motorcycle fatalities have risen while other motor vehicle fatalities have declined. Many motorcycle fatalities occurred within intersections after a driver failed to see a motorcyclist. However, little is known about the behavior of motorcyclists when they negotiate an intersection. A study was undertaken to compare the behavior at intersections of an experienced group of motorcyclists when they were operating a motorcycle with their behavior when they were driving a car. Each participant navigated a course through low-volume, open roads. Participants wore eye-tracking equipment to record eye-glance information, and the motorcycle and car were instrumented with an onboard accelerometer and Global Positioning System apparatus. Results showed that participants were more likely to make last glances toward the direction of the most threatening traffic before they made a turn when they were driving a car than when they were riding a motorcycle. In addition, motorcyclists were less likely to come to a complete stop at a stop sign than car drivers. These results suggested that motorcyclists were exposing themselves to unnecessary risk. Specifically, motorcyclists frequently failed to make proper glances and practice optimal riding techniques. The behavior of the motorcyclists was compared with the current Motorcycle Safety Foundation curriculum. The results suggested that threat-response and delayed-apex techniques should be added to the training curriculum.

Identifying motion and interest patterns of shoppers for developing personalised wayfinding tools

The development of wayfinding and information tools for pedestrians faces several challenges. In contrast to common navigation tools used for vehicles, navigation services for pedestrians must fulfil more complex requirements in order to be accepted. For pedestrians, the shortest path does not always represent the optimal route for an individual's purposes, as studies have revealed that people often forgo to take the shortest path and prefer the ‘most beautiful’, ‘most convenient’ or ‘safest’ path. People exploring a new environment on foot would therefore especially benefit from systems providing information concerning route qualities, interesting facilities in the vicinity and other useful location-related suggestions. As part of the scientific project ‘UCPNavi’, we investigate group-specific spatio-temporal behaviour and related influence factors of shoppers in order to identify homogeneous behaviour types based on motion patterns and information requirements. We use an eclectic approach combining several complementary empirical methods of data collection and analysis to thoroughly comprehend pedestrian spatio-temporal behaviour. In this contribution, we present results of motion and interview data analysis based on data collected from more than 100 participants during two empirical phases on a shopping street in Vienna. We further introduce an initial pedestrian typology comprising five different homogeneous behaviour types based on qualitative-interpretative and quantitative-statistical data. Types are described according to characteristic attributes identified by route choice behaviour, walking patterns and interest foci. The relevant factors include velocities, stopping behaviour, categories of visited facilities and individual preferences. The resulting typology of lifestyle-based pedestrian mobility styles and the identified characteristic attributes can serve as a basis to create pedestrian interest profiles in ubiquitous environments and to customise navigational and environmental information for mobile applications in order to fulfil individual needs.

Operation Theory of Wind Pumps

A theoretical formulation of the operation of wind pumps is proposed, including the starting and stopping behaviour. The paper defines a wind pump form of Froude number as the basic dimensionless parameter of the system. The influence of the turbine's power levels at low tip-speed ratios on the system performance is studied. The study is based on theoretical analysis and confirmed by experimental findings on the behaviour of constant-torque machines.

Early stopping rules employing early progression and response compared with conventional stopping rules in actual phase II trials.

e13004 Background: The traditional endpoint of phase II studies, response rate (RR), may not be appropriate for agents that inhibit growth but do not shrink the tumor. For these agents, early progressive disease (EPD), i.e., progression at first tumor measurement after treatment, may provide an additional measure of drug activity. Using a previously developed set of stopping rules employing both RR and EPD (dual endpoint stopping rule, DESR), the outcomes of completed phase II trials was compared with the conventional rules of Fleming and Gehan. Methods: We previously created a computer model (JCO 2008, 3715-3720) that determined patient RR and EPD thresholds needed to achieve the desired power and alpha error for a single-arm two-stage study. The EPD rate of interest was set as ≥ 0.4 and the EPD rate of disinterest as ≥ 0.6. The performance of this model in assessing agent activity was evaluated using a publically available set of phase II trial results (Dent et al, JCO, 2001, pp785-91), which were originally designed based on either the Fleming (16 trials) or Gehan (23 trials) designs. Results: Of the 10 trials stopped by the Fleming design at stage I, the DESR design stopped four. Of the 6 studies permitted to accrue to stage II by Fleming, one was stopped by investigators, while the Fleming design rejected the null hypothesis (Hnul) at the end of the second stage in 2 of the remaining 5 while the DESR design rejected Hnul in all 5 trials. All differences were due to high EPD. For studies conducted under the Gehan design, eight were stopped at stage I for acceptance of Hnul by both Gehan and the DESR. For the 15 studies accruing to stage II according to the Gehan design, Hnul was rejected in eight by both Gehan and DESR designs. However, the DESR would have stopped the other seven at the first stage on account of high EPD rates. Conclusions: In this study set of trials, the DESR was more likely than the Fleming rule to reject Hnul. Conversely, the DESR rejected Hnul for the same drugs as Gehan but was more likely to recommend stopping at stage I. The EPD rates of interest heavily influence the stopping behavior of the DESR. Alternate EPD values will be assessed. No significant financial relationships to disclose.

Race-Sensitive Choices by Police Officers in Traffic Stop Encounters

This study introduces a statistical estimator that can be used to examine disproportionate traffic stop behavior of police officers. This estimator can be employed in concert with internal benchmark data and a tree diagram algorithm to identify and classify disproportionate behavior. These methodologies are multilevel and can be used (a) at the macrolevel to examine disproportionality of a police department as an organization and (b) at the microlevel to draw inferences about reasons for individual officers’ disproportionate behavior. These statistical routines were tested using data from a medium sized midwestern community. Results suggest that the models are effective in detecting disproportionality in both a police organization and an individual officers’ traffic stop activity. Moreover, the methods may serve as an initial step in pointing toward the sources of the officers’ behavior.

Observation-Based Study of Intersection Dilemma Zone Natures

Yellow phase dilemma zone is dynamically distributed at high-speed signalized intersections because of varying driving behaviors in response to yellow indications. This article presents an observation-based study of the natures of dynamic dilemma zones. A case study was conducted at a high-speed intersection in Fairfield, Ohio. Time-based yellow-onset trajectories were obtained using the video-capture-based technique and then they were used to analyze three types of dynamic dilemma zone models: that is, Type I and II dilemma zones, and option zone. The results reveal that the contributing factors of Type I dilemma zone and option zone are not constant but dynamic at different speeds. Vehicle type has been proved a factor that significantly affects drivers’ stopping behavior. Drivers of trucks are more likely to make pass decisions than drivers of passenger vehicles. Cars, sport utility vehicles, vans, and light trucks have similar downstream boundaries of Type II dilemma zone whereas heavy trucks have the furthest upstream boundary of Type II dilemma zone. Finally, the comparison between the option zone and the Type II dilemma zone is analyzed using the sample data.

Spatial Forms and Signage in Wayfinding Decision Points for Hospital Outpatient Services

This study primarily researches the influence of wayfinding decision point spatial forms and signage on wayfinding behaviors in hospital outpatient areas, using spatial syntax analysis to perform axial mapping analysis and isovist analysis. We then perform a wayfinding experiment involving 24 experimental subjects, combining visual records and the records of behavior to perform analysis and categorization for wayfinding, visual content and behavior-producing decision point space forms. Finally, we compile the results of the experiment to investigate the effect of decision point spatial configuration, signage, and other factors on wayfinding behaviors. The primary results of our research include the following three points: (1) the most probable behavior produced in wayfinding was the stop behavior; visual content relied primarily upon direction signage; (2) wayfinding decision point node configurations that most often produced wayfinding behaviors were the closed form, the open L form, and the open form; (3) in terms of outpatient space wayfinding design, direction signage in closed forms and open L forms had the greatest effect on wayfinding.

The Post-Communist Fertility Puzzle

Fertility has unanimously declined across the entire post-communist region. This study explores the variation in fertility trends over time among these countries and assesses to what degree three explanations are applicable: second demographic transition (SDT), postponement transition (PPT) or reaction to the economic crisis. Moreover, on the basis of SDT and PPT theoretical tenets, as well as descriptive evidence, the economic context is hypothesized to be linked to two processes of fertility decline conversely. The results show that no one theoretical explanation is sufficient to explain the complex fertility declines across the entire post-communist region from 1990 to 2003. In some countries, a great part of the decline in fertility occurred before significant postponement of childbearing began, which indicates that the dramatic decline was due to stopping behavior or postponement of higher order births. Postponement of first births, either through PPT or SDT processes, greatly contributed to fertility decline in a small number of countries. Pooled cross-sectional time-series analyses of age-specific birthrates confirm that these two distinct processes are present and show that the economic crisis explanation has explanatory power for declining birth rates. In contrast, logistic regressions show that the likelihood of postponing childbirth increases with improved economic conditions. These results confirm the importance of taking the economic context into account when discussing explanations for fertility decline. More specifically, the results indicate that the severity and duration of economic crisis, or absence thereof, influenced the extent and manner in which fertility declined.

Ultra-cold plasmas: a paradigm for strongly coupled and classical electron fluids

AbstractUltra-cold plasmas obtained by ionization of atomic Rydberg states are qualified as classical and strongly coupled electron fluids. They are shown to share several common trends with ultra-cold electron flows used for ion-beam cooling. They exhibit specific stopping behaviour to charged particle beams, which may be used for diagnostic purposes. Ultra-cold plasmas are easily strongly magnetized. Then, one expects a strongly anisotropic behaviour of low ion velocity slowing down when the target electron cyclotron radius becomes smaller than the corresponding Debye length.

Soap Operas and Fertility: Evidence from Brazil

We estimate the effect of television on fertility in Brazil, where soap operas portray small families. We exploit differences in the timing of entry into different markets of Globo, the main novela producer. Women living in areas covered by Globo have significantly lower fertility. The effect is strongest for women of lower socioeconomic status and in the central and late phases of fertility, consistent with stopping behavior. The result does not appear to be driven by selection in Globo entry. We provide evidence that novelas, and not just television, affected individual choices, based on children's naming patterns and novela content. (JEL J13, J16, L82, O15, Z13)

Behavioral and neural responses of juvenile crayfish to moving shadows

One of the most important decisions any animal has to make is how to respond to sensory cues that suggest an imminent attack by a predator. We measured behavioral and neural responses of juvenile crayfish to moving shadows of different velocities while the animals were searching for food. In all experiments, and independent of shadow velocity, each crayfish produced one of two discrete behavioral outputs: it either tail-flipped backwards by rapid flexion of its abdomen or it immediately stopped its forward locomotion. The probability of each behavioral response was dependent on the velocity of the shadows that were presented. While most animals responded with tail-flips to slow-moving shadows and stops were rarely observed, the number of tail-flips decreased as shadow velocity increased. Tail-flips were almost absent for very fast-moving shadows and stopping behavior became the dominating response. By using a non-invasive technique to record neural activity, we were able to identify the underlying neural circuit that controlled the observed tail-flips. All tail-flips were mediated by activation of the medial giant neurons, which are part of a hardwired neural circuit previously described to produce reflexive responses to tactile stimulation.

Analysis of Stopping Behavior at Urban Signalized Intersections

Traffic accidents at signalized intersections are influenced by many environmental factors, including site layout, traffic volume, and signal operation. However, most traffic accidents are attributable to driver behavior in response to the environment, because responses to the environment vary with drivers’ individual characteristics, as observed in the concept of a dilemma zone (DZ) at intersection approaches. For DZ protection, the installation of traffic signals closer to the stop line (i.e., before the intersection) has been proposed in South Korea. Although such proposals have been implemented experimentally, the actual effect of this measure on driver behavior has not yet been investigated. A discrete choice model is used to identify the factors that influence drivers’ crossing and stopping behaviors at signalized intersections, under the assumption that traffic safety is at risk if the influence of the signal location is ignored. Two analyses are presented to assess the impact of signal location on driver behavior at intersections. Violations of stop line crossing behavior and remaining time to stop line are examined, and two types of driver behavior models are presented that address the effects of signal location and other factors. The results consistently reveal that traffic signal location affects drivers’ stopping behavior, suggesting that traffic signal location can jeopardize road safety and therefore should be considered in intersection design.

Driver Stopping Behavior on High-Speed Signalized Intersection Approaches

The research presented in this paper characterizes driver stopping behavior at the onset of a yellow phase on high-speed signalized-intersection approaches through the use of controlled field data gathered from 60 test subjects by means of an in-vehicle differential global positioning system. A total of 745 data records were available for analysis of all drivers who stopped at the onset of the yellow phase. These ranged from a minimum time to the stop bar (TTS) of 1.34 s to a maximum of 6.19 s. Statistical analyses were used to investigate the effects of the TTS bar, grade (uphill and downhill), age (younger than 40 years old, 40 to 59 years old, and 60 years of age or older), and gender on seven dependent measures of driver performance, including perception time, reaction time, perception–reaction time, braking time, stopping time, and stopping accuracy. The study demonstrated that driver perception time was not affected by TTS, while reaction time was dependent on TTS, roadway grade, and driver age. Younger drivers had longer reaction times than the older group, but they were able to stop over a shorter period of time, as they typically applied more aggressive braking rates. A lower perception–reaction time was found for drivers who had their foot lifted off the accelerator at the onset of the yellow phase. Male drivers showed slightly higher braking times than female drivers, with no significant differences between male and female drivers. Furthermore, the results demonstrated that drivers who tried to stop in short TTSs were more likely to stop downstream of the stop line and that older drivers were significantly more accurate when they stopped than other age groups.

A simple technique for automated performance testing of piezoelectric micro-motors by transient motion analysis

An automated method of testing a 5 mm diameter flextensional ultrasonic motor has been assembled using off-the-shelf components, which derives performance measurements from the transient start up and stopping behaviour of the motor using a non-contact position encoder. The method gives full performance characteristics in less than a second and it is scaleable for use with other sizes and other types of motor. Furthermore, it provides a relatively simple technique for non-contact measurements of position, angle or velocity that can be rapidly cycled as part of a development programme. The method has shown sufficient sensitivity, using basic components, to measure torque in the range 10–200 μN m and speed in the range from 0 to over 2000 rpm. The torque and speed ranges are only dependant on the sensitivity of encoder instrumentation, inertial load on the motor and data acquisition. This system is believed to be a significant improvement over previously reported work that has detailed friction brake or manual ‘one-off’ systems and the test format has greater applicability for micro-motors that are used for their positioning capabilities.

Rethinking Historical Reproductive Change: Insights from Longitudinal Data for a Spanish Town

A set of linked reproductive histories taken from the Spanish town of Aranjuez between 1871 and 1950 is used to address key issues regarding reproductive change during the demographic transition. These include the role of child survival as a stimulus for reproductive change, the use of stopping and/or spacing strategies to achieve reproductive goals, and the timing of change. Straightforward demographic measures are used and robust results are achieved. Initial strategies of fertility limitation are shown to exist but are inefficient, are mostly visible during the latter part of the reproductive period, are designed mostly to protect families from the effects of increases in child survival, and are based almost entirely on stopping behavior. As mortality decline accelerates, strategies become much more efficient, are visible at the outset of married life, include spacing behavior, and eventually lead to important declines in completed family size. The results of this study have implications for our understanding of the demographic transition both in historical Europe and in other regions of the world.

Subjective impulsivity and baseline EEG in relation to stopping performance

Impulsivity is a personality trait within the normal population, but also a feature of many psychiatric disorders that have been associated with poor inhibitory control. The aim of the present study was to examine the relation between subjective impulsivity, theta/beta EEG ratio, and inhibitory control in healthy individuals. In 15 high and 14 low impulsive healthy volunteers (as assessed by the I 7 questionnaire), resting state EEG was recorded during an eyes open condition to obtain estimates for theta and beta activity. Subsequently, a stop-signal task was presented where participants responded to go-signals and had to stop their initiated response to stop-signals. Stopping performance and EEG activity were compared between the impulsive groups as well as between high vs. low theta/beta ratio groups. Results showed that subjective impulsivity was not related to stopping behavior or to theta/beta ratio. In contrast to our expectations that individuals with high theta/beta ratios would show relatively long stopping reaction times, analyses revealed that the low theta/beta ratio group had longer stopping reaction times. Given that increased theta/beta ratio may reflect reduced cortical inhibition over subcortical drives, it is proposed that healthy individuals with relative high theta/beta ratios are more motivated to maximize inhibition-related performance.

Influence of residual stresses and mean load on the fatigue strength of case-hardened notched specimens

Case-hardened gear wheels, e.g., in vehicle transmissions are cyclically most stressed components. Their lifetime is determined by the interaction of loading, tooth flank load-capacity and tooth foot load-capacity. The latter is influenced by a multitude of parameters like mean loading or residual stress state appearing during operation. To evaluate the tooth-foot load-capacity, the knowledge of the mean stress and residual stress sensitivity of the fatigue strength of the material conditions at the sites critical for failure is necessary. The examinations on hand concerning means stress sensitivity and residual stress sensitivity usually deal with homogeneous materials. Systematic analyses for case-hardened conditions are missing. In this work case-hardened notched specimens with different residual stress states are investigated under cyclic bending. The results are analyzed using a local concept and an additional fracture mechanical approach. With the local concept it was possible to determine the crack initiation site which was partly at the surface and partly below the surface. The fracture mechanical approach was necessary to understand the crack stop behavior and to determine the site critical for failure. An uniform description of the lifetime behavior of unpeened and shot peened specimen could be achieved using a modified Haigh diagram which takes into account the local stress state at the site critical for failure.

The decline of illegitimacy and the control of marital fertility during the demographic transition. Testing the innovation-diffusion hypothesis using cohort fertility data from a Belgian town, 1850-1910

One of the major arguments made in the litera ture in support of the view that the European fertility transi tion was the result of the spread of an innovation called con traception, is that illegitimate fertility fell together with marital fertility. Indeed, the parallel decline of both illegiti macy and marital fertility in the final part of the nineteenth century suggests that individuals in Europe were applying new forms of contraceptive behaviour that were previously not done or even unthinkable. The aim of this contribution in to investigate one implication of the argument: if the dif fusion hypothesis is correct, one would expect that women who got children before marriage would be less likely to control their fertility by means of parity-dependent stopping behaviour within marriage than comparable women without premarital births. This hypothesis is investigated with a lo gistic regression model of stopping behaviour using data from three birth cohorts living in the Belgian town of Leu ven between 1850 and 1910. The results indicate that, at least in Leuven, the decline of illegitimacy can at most only partly be explained by the diffusion of innovative contra ceptive behaviour. More than backing up the diffusionist in terpretation, the findings lend particular support to the courtship model of premarital pregnancies and births. The