Design and Characterization of a Single Lever Bicycle Brake with Hydraulic Pressure Proportioning

Featured Application: The work described here aims to design and characterize a more efficient bicycle braking system. In 2019, the Centers for Disease Control and Prevention estimated that 329,000 Americans were injured in cycling-related incidents. Since the first bicycle brake in 1817, there has been an individual brake lever for decelerating each wheel, while on cars, there has been a single control lever for decelerating multiple wheels since 1921. To perform an emergency stop on a bicycle, the rider must proportion hand pressure on each brake lever and simultaneously vary hand pressure throughout the duration of the maneuver to match the variations of normal force on each tire. Only highly skilled riders, with years of training and practice, can correctly proportion brake pressure to maximize available traction and thus minimize stopping distances. The objective of this study is to simulate and prototype a hydraulic, single-lever bicycle brake system, integrating front and rear brake proportioning, which minimizes stopping distance compared to dual-lever simulations. A design is developed to address the brake proportioning issue. Based on the simulations and physical model, the prototype proportioning valve decreased simulated stopping distances up to 18%. Exploring a range of bike types and scenarios, stopping distances were decreased between 13% and 26%. Simulating an ideal proportioning valve, stopping distances were further decreased between 4% and 40%. These results show that there can be an advantage to brake proportioning technologies in bicycles

Technical note: Measuring tropospheric OH and HO₂ by laser-induced fluorescence at low pressure. A comparison of calibration techniques

International audienceThe hydroxyl radical (OH) is one of the most important oxidants in the atmosphere, as it is involved in many reactions that affect regional air quality and global climate change. Because of its high reactivity, measurements of OH radical concentrations in the atmosphere are difficult, and often require careful calibrations that rely on the production of a known concentration of OH at atmospheric pressure. The Indiana University OH instrument, based on the Fluorescence Assay by Gas Expansion technique (FAGE), has been calibrated in the laboratory using two different approaches: the production of OH from the UV-photolysis of water-vapor, and the steady-state production of OH from the reaction of ozone with alkenes. The former technique relies on two different actinometric methods to measure the product of the lamp flux at 184.9 nm and the photolysis time. This quantity derived from N2O actinometry was found to be 1.5 times higher than that derived from O2 actinometry. The water photolysis and ozone-alkene techniques are shown to agree within their experimental uncertainties (respectively 17% and 44%), although the sensitivities derived from the ozone-alkene technique were systematically lower by 40% than those derived from the water-vapor UV- photolysis technique using O2 actinometry. The agreement between the two different methods improves the confidence of the water-vapor photolysis method as an accurate calibration technique for HOx instruments. Because several aspects of the mechanism of the gas phase ozonolysis of alkenes are still uncertain, this technique should be used with caution to calibrate OH instruments

Parametrising Star Formation Histories

We examine the star formation histories (SFHs) of galaxies in smoothed particle hydrodynamics (SPH) simulations, compare them to parametric models that are commonly used in fitting observed galaxy spectral energy distributions, and examine the efficacy of these parametric models as practical tools for recovering the physical parameters of galaxies. The commonly used tau-model, with SFR ~ exp(-t/tau), provides a poor match to the SFH of our SPH galaxies, with a mismatch between early and late star formation that leads to systematic errors in predicting colours and stellar mass-to-light ratios. A one-parameter lin-exp model, with SFR ~ t*exp(-t/tau), is much more successful on average, but it fails to match the late-time behavior of the bluest, most actively star-forming galaxies and the passive, "red and dead" galaxies. We introduce a 4-parameter model, which transitions from lin-exp to a linear ramp after a transition time, which describes our simulated galaxies very well. We test the ability of these parametrised models to recover (at z=0, 0.5, and 1) the stellar mass-to-light ratios, specific star formation rates, and stellar population ages from the galaxy colours, computed from the full SPH star formation histories using the FSPS code of Conroy et al. (2009). Fits with tau-models systematically overestimate M/L by ~ 0.2 dex, overestimate population ages by ~ 1-2 Gyr, and underestimate sSFR by ~ 0.05 dex. Fits with lin-exp are less biased on average, but the 4-parameter model yields the best results for the full range of galaxies. Marginalizing over the free parameters of the 4-parameter model leads to slightly larger statistical errors than 1-parameter fits but essentially removes all systematic biases, so this is our recommended procedure for fitting real galaxies.Comment: 28 pages, 18 figure

Estimation of Standby Power Consumption for Typical Appliances

In the past days, many consumers could simply unplug their appliances and go on holidays, assuming that their electricitymeter would just stop. Standby power is a power consumed by an appliance when switched off or not performing its primaryfunctions. Standby power consumption provides good opportunity for reducing both energy consumption and green housegas emissions. Through co-operation among governments, industry and consumers and the co-ordination of internationalpolicies, standby modes can be made more efficient, thereby reducing the overall demand for power.In this paper, standby power consumption of various domestic appliances was determined using an energy cost meter. Theexperimental results shows that the standby power of various house hold electrical appliances is consuming more electricityduring standby mod

Maternal near miss review from a tertiary care center in South India

Background: Maternal near miss review acts as complimentary for mortality audits. It indicates the quality of obstetric care and helps obstetricians to revise policies and practices.Methods: A retrospective observational study was carried out at institute of maternal and child health, Government Medical College Kozhikode from January to December 2014. Cases were defined based on WHO criteria 2009.Results: Total live births during the study period were 15604 and there were 24 maternal deaths. Near Miss cases were 267. Maternal mortality rate was 153.5/lakh live births and maternal near miss incidence ratio was 17.03/1000 live births. Maternal near miss to mortality ratio was 11.1 and mortality index was 8.2%. Hypertensive disorders comprised 46%, followed by haemorrhage 36%, sepsis 7% and other causes 10%.Conclusions: Even with improving care, maternal near miss incidence (17.03 per 1000 live births) is found to be higher in our institution compared to developed nations. However high maternal near miss to mortality ratio (11.1) and low mortality index (8.2%) shows good quality of obstetric care in our institution

Measurements of OH and HO2 concentrations during the MCMA-2006 field campaign - Part 1: Deployment of the Indiana University laser-induced fluorescence

Measurements of tropospheric hydroxyl (OH) and hydroperoxy (HO2) radicals were made during the MCMA (Mexico City Metropolitan Area) field campaign as part of the MILAGRO (Megacity Initiative: Local and Global Research Observations) project during March 2006. These radicals were measured using a laser-induced fluorescence instrument developed at Indiana University. This new instrument takes advantage of the Fluorescence Assay by Gas Expansion technique (FAGE) together with direct excitation and detection of OH at 308 nm. HO2 is indirectly measured as OH by titration with NO inside the fluorescence cell. At this stage of development, IU-FAGE is capable of detecting 3.9×105 molecule/cm3 of both OH and HO2, with a signal to noise ratio of 1, an averaged laser power of 10-mW and an averaging time of 5-min. The calibration accuracies (1 omega) are ±17% for OH and ±18% for HO2 using the water-vapor photolysis/O2 actinometry calibration technique. OH and HO2 concentrations were successfully measured at an urban site in Mexico City, with observed concentrations comparable to those measured in other polluted environments. Enhanced levels of OH and HO2 radicals were observed on several days between 09:30–11:00 a.m. and suggest an intense photochemistry during morning hours that may be due to elevated sources of HOx (OH+HO2) and a fast cycling between the radicals under the high NOx (NO+NO2) conditions of the MCMA.National Science Foundation (U.S.) (ATM-9984152)National Science Foundation (U.S.) (0612738)Henry & Camille Dreyfus Foundatio

Automatic generation control of a hydro - thermal and thermal - thermal systems in a deregulated environment

This paper deals with the applications of automatic generation control (AGC) of a hydro —thermal and thermal—thermal systems in a power system deregulated environment and makes an attempt to provide a new practical AGC model to fulfill the needs of a modern restructured hydro-thermal and thermal -thermal power system. Several Distribution Company, distribution Participation Matrix,and area participation factor have been tried out and dynamic responses for frequency, tie line flow and power generations are obtained to examine the performance of the system in deregulated environment considering integral controllers. Investigations have been also carried out to study the effect of generation rate constraint and the importance of APF in deregulated environment. Study also reveals that the conventional integral controllers are quite robust than PI and PID controllers and the optimum integral gains once set for nominal condition need not be changed for +25% variations in system parameters and +20% variations in operating load condition from their nominal values

Signature capture of red soil patches and their acidity-A case study of Banka district, Bihar, India

Colour in soils as well as other object is the visual perceptual property which is perceived by human eye. They are governed by spectrum of light corresponding to wavelength or reflected energy of the material. Developed model for soil acidity is based on visual interpretation, principal component and spectral enhancement techniques by using of the satellite image (IRS LISS III, 2014). In this context, red soil patch is much sensitive in red spectral band comparison to green and blue spectral bands and perceived as red tone by human eyes but same soil patch appears green in false colour composite (FCC) image of NIR (0.70-0.80?m), Red (0.60-0.70 ?m) and Green (0.50-0.60?m) bands. The maximum coverage of red soil patches having low pH < 6.5 (1:2.5) was recognized in 44.07 per cent of the total geographical area (3019.56 sq.km) under Banka district. Maximum red soil patches having their acidity were recognised in Katoria (18.56%), Chanan (15.15%), Bounsi (10.44%) and Banka (9.92%) blocks. Overall results indicated that variation of tone in different bands helps for the separation of red soil patches