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1
Prasolenko, O. „IMPACT OF ROAD TRAFFIC ON DRIVER REACTION TIME“. Municipal economy of cities 6, Nr. 159 (27.11.2020): 169–72. http://dx.doi.org/10.33042/2522-1809-2020-6-159-169-172.
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The main problem of driving safety in the dark for drivers is the recognition of elements of the traffic situation. Changes in the characteristics of visual perception are due to changes in illumination, brightness of the color contrast of important and significant for the driver stimuli during movement. It is the recognition of existing obstacles in terms of contrast and brightness that is the biggest problem for drivers. When driving at night, drivers are prone to dazzle, they are less able to distinguish colors, and the field of view is significantly reduced. The availability of technical means for regulating traffic in accordance with road conditions and pedestrian traffic in the dark are the main means that allow the driver to navigate while driving. The driver's reaction time to the appearance of danger is decisive in the event of conflict situations in the dark. Driver reaction time is an important indicator of road safety. The reaction time is constantly changing and depends on many factors of working conditions, the functional state of the driver. Working conditions cause fatigue and emotional stress. The change in reaction time depends on the state of health, the intake of certain medications, the state of drug and alcohol intoxication, etc. In addition, a person's age, gender and experience also affect the reaction time. A simpler and more effective method for studying the distribution of reaction time and patterns of change is the use of an individual car with recording equipment. It has been proven that car drivers can keep their distance, brake synchronously and maintain braking force in accordance with the leading car braking and being in front. Therefore, to study the parameters of movement along the route, we used the device racelogic "VideoVbox". Experimental studies on city streets at night have been carried out, have shown the relationship between the driver's reaction time and traffic conditions. The study involved drivers between the ages of 20 and 40. As a result, regularities were obtained for the change in the reaction time under different lighting conditions and the traffic load factor of the streets. It has been found that with a low load factor, the driver is more likely to be distracted and has a worse reaction time. The optimal load for the driver is a load factor ranging from 0.35-0.55 with the best response times. The constructed model of the driver's reaction time can be used in expert practice to establish the circumstances of the occurrence of road accidents.
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Lotz, Alexander, Nele Russwinkel und Enrico Wohlfarth. „Take-over expectation and criticality in Level 3 automated driving: a test track study on take-over behavior in semi-trucks“. Cognition, Technology & Work 22, Nr. 4 (04.03.2020): 733–44. http://dx.doi.org/10.1007/s10111-020-00626-z.
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Abstract With the introduction of advanced driving assistance systems managing longitudinal and lateral control, conditional automated driving is seemingly in near future of series vehicles. While take-over behavior in the passenger car context has been investigated intensively in recent years, publications on semi-trucks with professional drivers are sparse. The effects influencing expert drivers during take-overs in this context lack thorough investigation and are required to design systems that facilitate safe take-overs. While multiple findings seem to cohere in passenger cars and semi-trucks, these findings rely on simulated studies without taking environments as found in the real world into account. A test track study was conducted, simulating highway driving with 27 professional non-affiliated truck drivers. The participants drove an automated Level 3 semi-truck while a non-driving-related task was available. Multiple time critical take-over situations were initiated during the drives to investigate four main objectives regarding driver behavior. (1) With these results, comparison of reaction times and behavior can be drawn to previous simulator studies. The effect of situation criticality (2) and training (3) of take-over situations is investigated. (4) The influence of warning expectation on driver behavior is explored. Results obtained displayed very quick time to hands on steering and time to first reaction all under 2.4 s. Highly critical situations generate very quick reaction times M = 0.81 s, while the manipulation of expectancy yielded no significant variation in reaction times. These reaction times serve as a reference of what can be expected from drivers under optimal take-over conditions, with quick reactions at high speed in critical situations.
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Amortila, Valentin, Elena Mereuta, Silvia Veresiu, Madalina Rus und Costel Humelnicu. „Positioning study of driver's hands in certain areas of the steering wheel“. MATEC Web of Conferences 178 (2018): 06014. http://dx.doi.org/10.1051/matecconf/201817806014.
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The aim of this paper is to analyze driver's hands coordinates on the steering wheel for an optimal and safe driving experience. A good coordination of the driver's action on the controls is the result of a comfortable position that leads to an optimal reaction while driving. The presented study implies using a thermal imaging camera for analysing palms temperature changes in the contact area with the steering wheel. The resulting data shows that the optimal driving position of drivers' hands is 0° and 180° associating the steering wheel with and trigonometric circle.
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Wan, Hongliang, Zhigang Du, Qixiang Yan und Xiaohong Chen. „EVALUATING THE EFFECTIVENESS OF SPEED REDUCTION MARKINGS IN HIGHWAY TUNNELS“. Transport 33, Nr. 3 (10.07.2018): 647–56. http://dx.doi.org/10.3846/transport.2018.1574.
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As typical weak visual reference systems, highway tunnels have low illumination, monotonous environment and few references, which may cause severe visual illusion and reduce drivers’ speed perception ability. Thus, drivers tend to underestimate their driving speed, which may induce speeding behaviours that result in rear-end collisions. The cost-effective pavement markings installed on both sides of the lane or shoulder may make drivers overestimate their speed. This perception can help ensure safe driving and regulate driving behaviour effectively. This study analyses the effects of sidewall markings in typical low luminance highway tunnels, specifically observing how their angles and lengths affect the driver’s speed perception. A three-dimensional model of highway tunnels was built in a driving simulator. Psychophysical tests of speed perception were carried out by the method of limits. The simulation tests studied the Stimulus of Subjectively Equal Speed (SSES) and reaction time in relation to sidewall markings with different angles. Furthermore, based on the optimal angle, the effects of sidewall marking with different lengths on speed perception were also analysed. The test results reveal that the angle and length of sidewall markings have a significant impact on the driver’s SSES and reaction time. Moreover, the level of speed overestimation decreases with the increase of angle or length of sidewall marking. As the angle of sidewall marking gradually increases, the maximum reaction time first increases and then decreases. Within the angle of sidewall marking of 15°, the subjects have the highest speed overestimation and an easy speed judgment. This may due to Zöllner illusion, the driver’s perception of lane width shrinks may induce deceleration behaviour.
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Bordin, Chiara, und Asgeir Tomasgard. „Behavioural Change in Green Transportation: Micro-Economics Perspectives and Optimization Strategies“. Energies 14, Nr. 13 (22.06.2021): 3728. http://dx.doi.org/10.3390/en14133728.
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The increasing demand for Electric Vehicle (EV) charging is putting pressure on the power grids and capacities of charging stations. This work focuses on how to use indirect control through price signals to level out the load curve in order to avoid the power consumption from exceeding these capacities. We propose mathematical programming models for the indirect control of EV charging that aim at finding an optimal set of price signals to be sent to the drivers based on price elasticities. The objective is to satisfy the demand for a given price structure, or minimize the curtailment of loads, when there is a shortage of capacity. The key contribution is the use of elasticity matrices through which it is possible to estimate the EV drivers’ reactions to the price signals. As real-world data on relating the elasticity values to the EV driver’s behaviour are currently non-existent, we concentrate on sensitivity analysis to test how different assumptions on elasticities affect the optimal price structure. In particular, we study how market segments of drivers with different elasticities may affect the ability of the operator to both handle a capacity problem and properly satisfy the charging needs.
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Ossen, Saskia, und Serge P. Hoogendoorn. „Car-Following Behavior Analysis from Microscopic Trajectory Data“. Transportation Research Record: Journal of the Transportation Research Board 1934, Nr. 1 (Januar 2005): 13–21. http://dx.doi.org/10.1177/0361198105193400102.
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The development of accurate and robust models in the field of car following has suffered greatly from the lack of appropriate microscopic data. Because of this lack, little is known about differences in car-following behavior between individual driver–vehicle combinations. This paper studies the car-following behaviors of individual drivers by making use of vehicle trajectory data extracted from high-resolution digital images collected at a high frequency from a helicopter. The analysis was performed by estimating the parameters of different specifications of the well-known Gazis–Herman–Rothery car-following rule for individual drivers. This analysis showed that a relation between the stimuli and the response could be established in 80% of the cases. The main contribution of this paper is that considerable differences between the car-following behaviors of individual drivers could be identified. These differences are expressed as different optimal parameter values for the reaction time and the sensitivity, as well as different car-following models that appear to be optimal on the basis of the data for individual drivers.
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Powell, Lyndsey R., Yanmei Piao und YuHuang Wang. „Optical Excitation of Carbon Nanotubes Drives Localized Diazonium Reactions“. Journal of Physical Chemistry Letters 7, Nr. 18 (07.09.2016): 3690–94. http://dx.doi.org/10.1021/acs.jpclett.6b01771.
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Liu, Chun Sheng. „Relationship Modeling for the Psychological Impact of Night Vision on Braking Distance“. Applied Mechanics and Materials 602-605 (August 2014): 242–44. http://dx.doi.org/10.4028/www.scientific.net/amm.602-605.242.
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The traditional braking model does not consider the impact of drivers' visual distance error, which leads to deviation in determining the distance between vehicles, and therefore effective braking model cannot be built. In order to solve this problem, the paper proposes a modeling method reflecting the relationship between psychology of night vision and braking distance to get the optimal braking reaction speed thus realizing intelligent emergency brake control. The experimental results show that the model takes the relationship between psychology of night vision and braking distance into consideration, increases the braking reaction speed of the drivers, and has high robustness.
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Yessentay, D. E., A. K. Kiyalbaev, S. N. Kiyalbay und N. V. Borisуuk. „RELIABILITY CRITERION AND A MODEL FOR DETERMINING THE OPTIMAL SPEED OF MOVEMENT ON AUTOMOBILE ROADS IN WINTER SLIDING CONDITIONS“. NEWS of National Academy of Sciences of the Republic of Kazakhstan 6, Nr. 444 (15.12.2020): 119–25. http://dx.doi.org/10.32014/2020.2518-170x.138.
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The article presents a model for establishing the optimal speed of movement on highways, taking into account the determination of the braking distance in winter slippery conditions. According to the research results, it was established that the main criterion for the formation of road accidents on highways in winter slippery conditions is the drivers' underestimation of the adhesion qualities of road surfaces. The main criterion of the model under consideration is the interaction of the car wheel (braking distance) with the road (adhesion coefficient) and is a complex that characterizes the stability of the car rolling over on slippery surfaces and the driver's actions in making an effective decision and the duration of the reaction time. In the proposed mathematical model, the accident rate on a slippery road is estimated by the coefficient of adhesion of icy road surfaces, the value of the load or the average wheel pressure. Also, the frequency of load application, the amount of deflection of the coating (at an air temperature above +20 ° C), rolling resistance, the coefficient of adhesion of the car wheel to the coating. One of the main characteristics of the model is a subsystem - the average pressure p = Q / S (S is the area of the imprint of the wheel, cm²), etc. Thus, in the process of analyzing the results of the causes of road traffic accidents, the factors of the driver's reliability and the decisions made will be taken into account, which depend on the speed of vehicles in any condition of the road surface.
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Svoboda, Martin, Milan Chalupa, Karel Jelen, František Lopot, Petr Kubový, Milan Sapieta, Zdeněk Krobot und Marcin Suszyński. „Load Measurement of the Cervical Vertebra C7 and the Head of Passengers of a Car While Driving across Uneven Terrain“. Sensors 21, Nr. 11 (02.06.2021): 3849. http://dx.doi.org/10.3390/s21113849.
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The article deals with the measurement of dynamic effects that are transmitted to the driver (passenger) when driving in a car over obstacles. The measurements were performed in a real environment on a defined track at different driving speeds and different distributions of obstacles on the road. The reaction of the human organism, respectively the load of the cervical vertebrae and the heads of the driver and passenger, was measured. Experimental measurements were performed for different variants of driving conditions on a 28-year-old and healthy man. The measurement’s main objective was to determine the acceleration values of the seats in the vehicle in the vertical movement of parts of the vehicle cabin and to determine the dynamic effects that are transmitted to the driver and passenger in a car when driving over obstacles. The measurements were performed in a real environment on a defined track at various driving speeds and diverse distributions of obstacles on the road. The acceleration values on the vehicle’s axles and the structure of the driver’s and front passenger’s seats, under the buttocks, at the top of the head (Vertex Parietal Bone) and the C7 cervical vertebra (Vertebra Cervicales), were measured. The result of the experiment was to determine the maximum magnitudes of acceleration in the vertical direction on the body of the driver and the passenger of the vehicle when passing a passenger vehicle over obstacles. The analysis of the experiment’s results is the basis for determining the future direction of the research.
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Ge, Jin I., und Gabor Orosz. „Optimal Control of Connected Vehicle Systems With Communication Delay and Driver Reaction Time“. IEEE Transactions on Intelligent Transportation Systems 18, Nr. 8 (August 2017): 2056–70. http://dx.doi.org/10.1109/tits.2016.2633164.
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Mańkowski, Tomasz, Jakub Tomczyński, Krzysztof Walas und Dominik Belter. „PUT-Hand—Hybrid Industrial and Biomimetic Gripper for Elastic Object Manipulation“. Electronics 9, Nr. 7 (16.07.2020): 1147. http://dx.doi.org/10.3390/electronics9071147.
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In this article, the design of a five-fingered anthropomorphic gripper is presented specifically designed for the manipulation of elastic objects. The manipulator features a hybrid design, being equipped with three fully actuated fingers for precise manipulation, and two underactuated, tendon-driven digits for secure power grasping. For ease of reproducibility, the design uses as many off-the-shelf and 3D-printed components as possible. The on-board controller circuit and firmware are also presented. The design includes resistive position and angle sensors in each joint, resulting in full joint observability. The controller has a position-based controller integrated, along with USB communication protocol, enabling gripper state reporting and direct motor control from a PC. A high-level driver operating as a Robot Operating System node is also provided. All drives and circuitry of the PUT-Hand are integrated within the hand itself. The sensory system of the hand includes tri-axial optical force sensors placed on fully actuated fingers’ fingertips for reaction force measurement. A set of experiments is provided to present the motion and perception capabilities of the gripper. All design files and source codes are available online under CC BY-NC 4.0 and MIT licenses.
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Davis, L. C. „Modifications of the optimal velocity traffic model to include delay due to driver reaction time“. Physica A: Statistical Mechanics and its Applications 319 (März 2003): 557–67. http://dx.doi.org/10.1016/s0378-4371(02)01457-7.
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Jia, Yanfeng, Dayi Qu, Xiaolong Ma, Lu Lin und Jiale Hong. „Molecular Dynamics Characteristics and Model of Vehicle-Following Behavior“. Journal of Advanced Transportation 2020 (05.12.2020): 1–11. http://dx.doi.org/10.1155/2020/8867805.
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The vehicle-following behavior is a self-organizing behavior that restores dynamic balance under the stimulation of external environmental factors. In fact, there are asymmetric problems in the process of acceleration and deceleration of drivers. The existing traditional models ignored the differences between acceleration and deceleration of vehicles. In order to solve this problem, the vehicles driving on the road are compared to interacting molecules. Vehicle-following characteristics are studied, and the molecular following model is established based on molecular dynamics. The model parameters under different conditions are calibrated considering the required safety distance by the vehicle and the reaction time of the driver. With the help of the vehicle running track graphs, speed, and acceleration graphs, the numerical simulations of the molecular following model and the classical optimal speed vehicle-following model are carried out. The results of the comparative analysis show that the acceleration in the process of acceleration and deceleration is not constant but more sensitive to the deceleration of the preceding vehicle than to the acceleration and more sensitive to the acceleration/deceleration of the short-distance vehicle than to the acceleration/deceleration of the long-distance vehicle. Therefore, the molecular following model can better describe the vehicle-following behavior, and the research results can provide a theoretical basis and a technical reference for the analysis of traffic flow dynamic characteristics and adaptive cruise control technology.
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Minschwaner, K., G. L. Manney, S. H. Wang und R. S. Harwood. „Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability“. Atmospheric Chemistry and Physics Discussions 10, Nr. 9 (28.09.2010): 22317–37. http://dx.doi.org/10.5194/acpd-10-22317-2010.
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Abstract. Diurnal variations in hydroxyl (OH) in the stratosphere and mesosphere are analyzed using measurements from the Aura Microwave Limb Sounder (MLS). The primary driver for OH diurnal variations is the ultraviolet actinic flux that initiates photochemical reactions which produce OH. The magnitude of this flux is governed largely by changes in solar zenith angle (SZA) throughout the day, and OH diurnal variations are well approximated by an exponential function of the secant of SZA. Measured OH concentrations are fit to a function of the form exp[−βsec(SZA)], where the parameter β is a function of altitude. We examine the magnitude of β and show that it is related to the optical depths of ultraviolet absorption by ozone and oxygen. Comparison of β values obtained from SLIMCAT model simulations with those derived from MLS observations shows very good agreement. The vertical profile of β from MLS can be represented by a simple analytic formulation involving the ozone and water vapor photodissociation rates. This formulation is used to infer the altitude dependence of the primary production mechanisms for OH: the reaction of excited-state atomic oxygen with water vapor versus the direct photodissociation of water vapor.
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Yang, Mihong, Huiyan Li, Xiaozhou Sun, Li Yang, Hailong Duan, Yanqiu Che und Chunxiao Han. „Toward Wearable EEG-based Alertness Detection System Using SVM with Optimal Minimum Channels“. MATEC Web of Conferences 214 (2018): 03009. http://dx.doi.org/10.1051/matecconf/201821403009.
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Alertness is the state of attention by high sensory awareness. A lack of alertness is one of the main reasons of serious accidents. Traffic accidents caused by driver’s drowsy driving have a high fatality rate. This paper presents an EEG-based alertness detection system. In order to ensure the convenience and long-term wearing comfort of EEG recordings, the wearable electrode cap will be the principal choice in the future, and the selection of channels will be limited. We first built a 3-D simulated driving platform using Unity3D. Then, we perform an experiment with driving drift task. EEG signals are recorded form frontal and occipital regions. We select data segments using the driving reaction time, classify the state of alertness with a support vector machine (SVM), and select the optimal combination of channels with minimum number of channels. Our results demonstrate that alertness can be classified efficiently with one channel (PO6) at accuracy of 93.52%, with two channels (FP1+PO6) at 95.85% and with three channels (FP1+PO6+PO5 and FP1+PO6+POZ) at 96.11%.
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Lee, Seongjin, Wonteak Lim, Myoungho Sunwoo und Kichun Jo. „Limited Visibility Aware Motion Planning for Autonomous Valet Parking Using Reachable Set Estimation“. Sensors 21, Nr. 4 (22.02.2021): 1520. http://dx.doi.org/10.3390/s21041520.
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Autonomous driving helps drivers avoid paying attention to keeping to a lane or keeping a distance from the vehicle ahead. However, the autonomous driving is limited by the need to park upon the completion of driving. In this sense, automated valet parking (AVP) system is one of the promising technologies for enabling drivers to free themselves from the burden of parking. Nevertheless, the driver must continuously monitor the automated system in the current automation level. The main reason for monitoring the automation system is due to the limited sensor range and occlusions. For safety reasons, the current field of view must be taken into account, as well as to ensure comfort and to avoid unexpected and harsh reactions. Unfortunately, due to parked vehicles and structures, the field of view in a parking lot is not sufficient for considering new obstacles coming out of occluded areas. To solve this problem, we propose a method that estimates the risks for unobservable obstacles by considering worst-case assumptions. With this method, we can ensure to not act overcautiously while moving safe. As a result, the proposed method can be a proactive approach to consider the limited visibility encountered in a parking lot. In the proposed method, occlusion can be efficiently reflected in the planning process. The potential of the proposed method is evaluated in a variety of simulations.
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Sheu, Jiuh-Biing, und Hsi-Jen Wu. „Driver perception uncertainty in perceived relative speed and reaction time in car following – A quantum optical flow perspective“. Transportation Research Part B: Methodological 80 (Oktober 2015): 257–74. http://dx.doi.org/10.1016/j.trb.2015.07.017.
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Schwartz, Ira B., Eric Forgoston, Simone Bianco und Leah B. Shaw. „Converging towards the optimal path to extinction“. Journal of The Royal Society Interface 8, Nr. 65 (13.05.2011): 1699–707. http://dx.doi.org/10.1098/rsif.2011.0159.
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Extinction appears ubiquitously in many fields, including chemical reactions, population biology, evolution and epidemiology. Even though extinction as a random process is a rare event, its occurrence is observed in large finite populations. Extinction occurs when fluctuations owing to random transitions act as an effective force that drives one or more components or species to vanish. Although there are many random paths to an extinct state, there is an optimal path that maximizes the probability to extinction. In this paper, we show that the optimal path is associated with the dynamical systems idea of having maximum sensitive dependence to initial conditions. Using the equivalence between the sensitive dependence and the path to extinction, we show that the dynamical systems picture of extinction evolves naturally towards the optimal path in several stochastic models of epidemics.
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Vizitiu, Cristian, Călin Bîră, Adrian Dinculescu, Alexandru Nistorescu und Mihaela Marin. „Exhaustive Description of the System Architecture and Prototype Implementation of an IoT-Based eHealth Biometric Monitoring System for Elders in Independent Living“. Sensors 21, Nr. 5 (06.03.2021): 1837. http://dx.doi.org/10.3390/s21051837.
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In this paper, we present an exhaustive description of an extensible e-Health Internet-connected embedded system, which allows the measurement of three biometric parameters: pulse rate, oxygen saturation and temperature, via several wired and wireless sensors residing to the realm of Noncommunicable Diseases (NCDs) and cognitive assessment through Choice Reaction Time (CRT) analysis. The hardware used is based on ATMEGA AVR + MySignals Hardware printed circuit board (Hardware PCB), but with multiple upgrades (including porting from ATMEGA328P to ATMEGA2560). Multiple software improvements were made (by writing high-level device drivers, text-mode and graphic-mode display driver) for increasing functionality, portability, speed, and latency. A top-level embedded application was developed and benchmarked. A custom wireless AT command firmware was developed, based on ESP8266 firmware to allow AP-mode configuration and single-command JavaScript Object Notation (JSON) data-packet pushing towards the cloud platform. All software is available in a git repository, including the measurement results. The proposed eHealth system provides with specific NCDs and cognitive views fostering the potential to exploit correlations between physiological and cognitive data and to generate predictive analysis in the field of eldercare.
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Massoz, Quentin, Jacques Verly und Marc Van Droogenbroeck. „Multi-Timescale Drowsiness Characterization Based on a Video of a Driver’s Face“. Sensors 18, Nr. 9 (25.08.2018): 2801. http://dx.doi.org/10.3390/s18092801.
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Drowsiness is a major cause of fatal accidents, in particular in transportation. It is therefore crucial to develop automatic, real-time drowsiness characterization systems designed to issue accurate and timely warnings of drowsiness to the driver. In practice, the least intrusive, physiology-based approach is to remotely monitor, via cameras, facial expressions indicative of drowsiness such as slow and long eye closures. Since the system’s decisions are based upon facial expressions in a given time window, there exists a trade-off between accuracy (best achieved with long windows, i.e., at long timescales) and responsiveness (best achieved with short windows, i.e., at short timescales). To deal with this trade-off, we develop a multi-timescale drowsiness characterization system composed of four binary drowsiness classifiers operating at four distinct timescales (5 s, 15 s, 30 s, and 60 s) and trained jointly. We introduce a multi-timescale ground truth of drowsiness, based on the reaction times (RTs) performed during standard Psychomotor Vigilance Tasks (PVTs), that strategically enables our system to characterize drowsiness with diverse trade-offs between accuracy and responsiveness. We evaluated our system on 29 subjects via leave-one-subject-out cross-validation and obtained strong results, i.e., global accuracies of 70%, 85%, 89%, and 94% for the four classifiers operating at increasing timescales, respectively.
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Paredes-Mella, Javier, Daniel Varela, Pamela Fernández und Oscar Espinoza-González. „Growth performance of Alexandrium catenella from the Chilean fjords under different environmental drivers: plasticity as a response to a highly variable environment“. Journal of Plankton Research 42, Nr. 2 (März 2020): 119–34. http://dx.doi.org/10.1093/plankt/fbaa011.
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Abstract Alexandrium catenella, the main species associated with harmful algal blooms, has progressively increased its distribution through one of the most extensive and highly variable fjord systems in the world. In order to understand this successful expansion, we evaluated the effects of different salinities, light intensity, temperatures, nitrogen (N) forms and nitrogen/phosphate (N:P) ratio levels on the growth performance, using clones isolated from different locations across its wide geographic distribution. Results showed that the growth responses were plastic and, in some cases, different reaction norms among clones were observed. Despite plasticity, the optimal growth of A. catenella (i.e. highest growth rate and highest maximal cells density) was reached within a narrow thermal range (12–15°C), while salinity (20–30 PSU) and light intensity (20–120 μmol m−2 s−1) ranges were wider. These results are partially consistent with the highest cell densities recorded in the field. Furthermore, optimal growth was reached using reduced forms of nitrogen (i.e. urea and NH4+) and in unbalanced N:P ratios (18:1 and 30:1). These characteristics likely allow A. catenella to grow in highly variable environmental conditions and might partly explain the recent expansion of this species.
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Brotosudarmo, Tatas H. P., und Richard J. Cogdell. „STUDY ON THE STRUCTURAL BASIS OF PERIPHERAL LIGHT HARVESTING COMPLEXES (LH2) IN PURPLE NON-SULPHUR PHOTOSYNTHETIC BACTERIA“. Indonesian Journal of Chemistry 10, Nr. 3 (14.12.2010): 401–8. http://dx.doi.org/10.22146/ijc.21450.
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Photosynthesis provides an example of a natural process that has been optimized during evolution to harness solar energy efficiently and safely, and finally to use it to produce a carbon-based fuel. Initially, solar energy is captured by the light harvesting pigment-protein complexes. In purple bacteria these antenna complexes are constructed on a rather simple modular basis. Light absorbed by these antenna complexes is funnelled downhill to reaction centres, where light drives a trans-membrane redox reaction. The light harvesting proteins not only provide the scaffolding that correctly positions the bacteriochlorophyll a and carotenoid pigments for optimal energy transfer but also creates an environment that can modulate the wavelength at which different bacteriochlorophyll molecules absorb light thereby creating the energy funnel. How these proteins can modulate the absorption spectra of the bacteriochlorophylls will be discussed in this review.
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Muto, Yu, Gen Hirao und Tamotsu Zako. „Transcription-Based Amplified Colorimetric Thrombin Sensor Using Non-Crosslinking Aggregation of DNA-Modified Gold Nanoparticles“. Sensors 21, Nr. 13 (24.06.2021): 4318. http://dx.doi.org/10.3390/s21134318.
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Gold nanoparticles (AuNPs) have been employed as colorimetric biosensors due to the color difference between their dispersed (red) and aggregated (blue) states. Although signal amplification reactions triggered by structural changes of the ligands on AuNPs have been widely used to improve measurement sensitivity, the use of ligands is limited. In this study, we designed a AuNP-based signal-amplifying sandwich biosensor, which does not require a conformational change in the ligands. Thrombin was used as a model target, which is recognized by two different probes. In the presence of the target, an extension reaction occurs as a result of hybridization of the two probes. Then RNA synthesis is started by RNA polymerase activation due to RNA promoter duplex formation. The amplified RNA drives aggregation or dispersion of the AuNPs, and a difference of the color if the AuNP solution is observed. As this detection system does not require a conformational change in the ligand, it can be generically applied to a wide range ligands.
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Dou, Liguang, Cunji Yan, Liangshu Zhong, Dong Zhang, Jingye Zhang, Xin Li und Liye Xiao. „Enhancing CO2 methanation over a metal foam structured catalyst by electric internal heating“. Chemical Communications 56, Nr. 2 (2020): 205–8. http://dx.doi.org/10.1039/c9cc07525a.
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We develop an electric internal heating method based on a Ni-foam structured catalyst for CO2 methanation, in which the Joule heat generated by electric current passing through the catalyst drives the reaction.
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Cardew, George, Siamak Noroozi, John E. Vinney und Mihai Dupac. „Optimal Group Configurations of Fibre Materials Based on Inclusion Modelling“. Key Engineering Materials 543 (März 2013): 414–17. http://dx.doi.org/10.4028/www.scientific.net/kem.543.414.
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The use of high performance composites is becoming increasingly common in safety critical components. The key driver behind this research is the need to develop a better understanding of through thickness stresses where fibres and matrix are not uniformly distributed throughout the thickness. Classical distribution of composite is not always possible due to problems associated with manufacturing processes. Poor fibre distribution through the thickness affects the through thickness properties and can compromise the structural integrity. This paper presents a semi-analytical tool that can be used for modelling of fibre group optimisation. It can be used for analysis at both microscopic (fibre resin interactions) and macroscopic (composite laminate) levels. At each level the components reactions to externally applied load have been investigated through its load transfer mechanisms. The effects of anisotropy, edge distance and pitch between fibres, numbers of rows and finally dissimilar fibre materials and fibre cross section have been considered.
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Ranganathan, R., S. Rakheja und S. Sankar. „Steady Turning Stability of Partially Filled Tank Vehicles With Arbitrary Tank Geometry“. Journal of Dynamic Systems, Measurement, and Control 111, Nr. 3 (01.09.1989): 481–89. http://dx.doi.org/10.1115/1.3153078.
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Steady turning model of a partially filled tank vehicle is developed by integrating the roll plane model of the partially filled arbitrarily shaped tank with the static roll plane model of an articulated vehicle. The rollover immunity of the tank vehicle is investigated through computer simulation. The motion of the free surface of liquid and the associated load shift encountered during steady turning are computed using an iterative algorithm. The influence of tank geometry and liquid fill level on the rollover immunity of the tank vehicles is presented. Rollover threshold levels of a tractor-semitrailer vehicle with tanks of circular, modified square and modified oval cross sections are investigated for various fill levels. The influence of compartmenting of the tank on the steady turning response of the vehicle is presented and an optimal order of unloading the various compartments is determined. The study concludes that load shift encountered during steady turning has an adverse effect on the overturning limits of the articulated liquid tank vehicles. The stability of such tank vehicles may be further affected by the dynamic fluid-structure interactions, vehicle transients and driver’s reaction.
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SAHGUSA, Shozo, Yoshiaki YANIAUCHI, Hiromitsu Mom, Atsushi ICHIKAWA und Akio YABE. „Development of an Objective Lens Actuator for Isolating the Drive Reaction Force Using Half-Phase Bandwidth Method for Thin-Type Optical Disc Drives.“ Journal of the Japan Society for Precision Engineering 60, Nr. 12 (1994): 1731–35. http://dx.doi.org/10.2493/jjspe.60.1731.
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Rajani, Balvant, und Solomon Tesfamariam. „Uncoupled axial, flexural, and circumferential pipesoil interaction analyses of partially supported jointed water mains“. Canadian Geotechnical Journal 41, Nr. 6 (01.12.2004): 997–1010. http://dx.doi.org/10.1139/t04-048.
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Pipelines used in the distribution of potable water are a vital part of everyday life. The pipelines buried in soilbackfill are exposed to different deleterious reactions; as a result, the design factor of safety may be significantly degraded and, consequently, pipelines may fail prematurely. Proactive pipeline management, which entails optimal maintenance, repair, or replacement strategies, helps increase the longevity of pipelines. The effect of different deterioration mechanisms and operating conditions needs to be understood to develop good proactive management practices. In this paper, a Winkler-type analytical model is developed to quantify the contributions of different stress drivers, e.g., pipe material type and size, bedding conditions, and temperature. Sensitivity analyses indicate that the extent of the unsupported length developed as a result of scour has a significant influence on the flexural pipesoil response. As well, plastic pipes tolerate less loss of support than metallic pipes.Key words: jointed water mains, Winkler model, pipesoil interaction, elastoplastic soil.
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Cappa, Christopher D., Christopher Y. Lim, David H. Hagan, Matthew Coggon, Abigail Koss, Kanako Sekimoto, Joost de Gouw, Timothy B. Onasch, Carsten Warneke und Jesse H. Kroll. „Biomass-burning-derived particles from a wide variety of fuels – Part 2: Effects of photochemical aging on particle optical and chemical properties“. Atmospheric Chemistry and Physics 20, Nr. 14 (22.07.2020): 8511–32. http://dx.doi.org/10.5194/acp-20-8511-2020.
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Abstract. Particles in smoke emitted from biomass combustion have a large impact on global climate and urban air quality. There is limited understanding of how particle optical properties – especially the contributions of black carbon (BC) and brown carbon (BrC) – evolve with photochemical aging of smoke. We analyze the evolution of the optical properties and chemical composition of particles produced from combustion of a wide variety of biomass fuels, largely from the western United States. The smoke is photochemically aged in a reaction chamber over atmospheric-equivalent timescales ranging from 0.25 to 8 d. Various aerosol optical properties (e.g., the single-scatter albedo, the wavelength dependence of absorption, and the BC mass absorption coefficient, MACBC) evolved with photochemical aging, with the specific evolution dependent on the initial particle properties and conditions. The impact of coatings on BC absorption (the so-called lensing effect) was small, even after photochemical aging. The initial evolution of the BrC absorptivity (MACBrC) varied between individual burns but decreased consistently at longer aging times; the wavelength dependence of the BrC absorption generally increased with aging. The observed changes to BrC properties result from a combination of secondary organic aerosol (SOA) production and heterogeneous oxidation of primary and secondary OA mass, with SOA production being the major driver of the changes. The SOA properties varied with time, reflecting both formation from precursors having a range of lifetimes with respect to OH and the evolving photochemical environment within the chamber. Although the absorptivity of BrC generally decreases with aging, the dilution-corrected absorption may actually increase from the production of SOA. These experimental results provide context for the interpretation of ambient observations of the evolution of particle optical properties in biomass-combustion-derived smoke plumes.
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Yan, Lirong, Tiantian Wen, Jiawen Zhang, Le Chang, Yi Wang, Mutian Liu, Changhao Ding und Fuwu Yan. „An Evaluation of Executive Control Function and Its Relationship with Driving Performance“. Sensors 21, Nr. 5 (04.03.2021): 1763. http://dx.doi.org/10.3390/s21051763.
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The driver’s attentional state is a significant human factor in traffic safety. The executive control process is a crucial sub-function of attention. To explore the relationship between the driver’s driving performance and executive control function, a total of 35 healthy subjects were invited to take part in a simulated driving experiment and a task-cuing experiment. The subjects were divided into three groups according to their driving performance (aberrant driving behaviors, including lapses and errors) by the clustering method. Then the performance efficiency and electroencephalogram (EEG) data acquired in the task-cuing experiment were compared among the three groups. The effect of group, task transition types and cue-stimulus intervals (CSIs) were statistically analyzed by using the repeated measures analysis of variance (ANOVA) and the post hoc simple effect analysis. The subjects with lower driving error rates had better executive control efficiency as indicated by the reaction time (RT) and error rate in the task-cuing experiment, which was related with their better capability to allocate the available attentional resources, to express the external stimuli and to process the information in the nervous system, especially the fronto-parietal network. The activation degree of the frontal area fluctuated, and of the parietal area gradually increased along with the increase of CSI, which implied the role of the frontal area in task setting reconstruction and working memory maintaining, and of the parietal area in stimulus–Response (S–R) mapping expression. This research presented evidence of the close relationship between executive control functions and driving performance.
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Jeong, Sangsoo, Youngmi Baek und Sang H. Son. „Component-Based Interactive Framework for Intelligent Transportation Cyber-Physical Systems“. Sensors 20, Nr. 1 (02.01.2020): 264. http://dx.doi.org/10.3390/s20010264.
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While emerging technology for self-driving automation in vehicles progresses rapidly, the transition to an era of roads full of fully connected and automated vehicles (CAVs) may take longer than expected. Until then, it is inevitable that CAVs should coexist and interact with drivers of non-autonomous vehicles (NAVs) in urban roads. During this period of transition, it is critical to provide road safety with the mixed vehicular traffic and uncertainty caused by human drivers. To investigate the issues caused by the coexistence and interaction with humans, we propose to build a component-based and interactive intelligent transportation cyber-physical systems (ITCPS) framework. Our design of the interactive ITCPS framework aims to provide a standardized structure for users by defining core components. The framework is specified by behavior models and interfaces for the desired ITCPS components and is implemented as a form of human and hardware-in-the-loop system. We developed an intersection crossing assistance service and an automatic emergency braking service as an example of practical applications using the framework. To evaluate the framework, we tested its performance to show how effectively it operates while supporting real-time processing. The results indicate that it satisfies the timing requirements of vehicle-to-vehicle (V2V) communication and the limited processing time required for performing the functions of behavior models, even though the traffic volume reaches the road capacity. A case study using statistical analysis is conducted to assess the practical value of the developed experimental environment. The results of the case study validate the reliability among the specified variables for the experiments involving human drivers. It has shown that V2V communication support has positive effects on road safety, including intersection safety, braking events, and perception-reaction time (PRT) of the drivers. Furthermore, V2V communication support and PRT are identified as the important indicators affecting road safety at an un-signalized intersection. The proposed interactive framework is expected to contribute in constructing a comprehensive environment for the urban ITCPS and providing experimental support for the analysis of human behavior in the coexistence environment.
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Christensen, Joseph A., Jinyuan Zhang, Jiawang Zhou, Jordan N. Nelson und Michael R. Wasielewski. „Near-Infrared Excitation of the peri-Xanthenoxanthene Radical Cation Drives Energy-Demanding Hole Transfer Reactions“. Journal of Physical Chemistry C 122, Nr. 41 (25.09.2018): 23364–70. http://dx.doi.org/10.1021/acs.jpcc.8b07819.
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Liang, Xiao (Joyce), S. Ilgin Guler und Vikash V. Gayah. „Joint Optimization of Signal Phasing and Timing and Vehicle Speed Guidance in a Connected and Autonomous Vehicle Environment“. Transportation Research Record: Journal of the Transportation Research Board 2673, Nr. 4 (April 2019): 70–83. http://dx.doi.org/10.1177/0361198119841285.
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A joint traffic signal optimization algorithm is proposed which utilizes connected vehicle (CV) information to identify optimum signal timing and phasing plans while also providing speed guidance to individual vehicles to minimize total number of stopping maneuvers. The contribution of this paper is provision of speed guidance to both autonomous (AVs) and human-driven speed guidance-enabled vehicles (SGVs), recognizing that the latter may not fully comply with the speed guidance and would require some delay (i.e., reaction time) to implement it. The control algorithm is triggered at regular discrete time intervals during which CV information is used to identify the presence of non-CVs and incorporate them into signal timing decision-making. Optimal speeds are determined for any AVs or SGVs so that they can travel through the intersection at the expected departure time without stopping, considering both acceleration/deceleration and human reaction times. Simulation tests are performed under different CV, AV, and SGV penetration rates, while explicitly modeling the potential human errors and varying acceptance levels. The results suggest that average delay and number of stops decrease with higher CV penetration rate. Furthermore, the number of stops decreases as the ratio of both AVs and SGVs increases. While AVs are about 10% more efficient than SGVs, human-driven vehicles still provide a benefit even when they do not fully comply with speed guidance information. Sensitivity tests suggest that operation is not significantly affected by the range of human driver errors in speed compliance or range of reaction times.
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Ji, Kyoungtae, Matko Orsag und Kyoungseok Han. „Lane-Merging Strategy for a Self-Driving Car in Dense Traffic Using the Stackelberg Game Approach“. Electronics 10, Nr. 8 (08.04.2021): 894. http://dx.doi.org/10.3390/electronics10080894.
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This paper presents the lane-merging strategy for self-driving cars in dense traffic using the Stackelberg game approach. From the perspective of the self-driving car, in order to make sufficient space to merge into the next lane, a self-driving car should interact with the vehicles in the next lane. In heavy traffic, where the possible actions of the vehicle are pretty limited, it is possible to conjecture the driving intentions of the vehicles from their behaviors. For example, by observing the speed changes of the human-driver in the next lane, the self-driving car can estimate its driving intention in real time, much in the same way of a human driver. We use the principle of Stackelberg competition to make the optimal decision for the self-driving car based on the predicted reaction of the interacting vehicles in the next lane. In this way, according to the traffic circumstances, a self-driving car can decide whether to merge or not. In addition, by limiting the number of interacting vehicles, the computational burden is manageable enough to be implemented in production vehicles. We verify the efficiency of the proposed method through the case studies for different test scenarios, and the test results show that our approach is closer to the human-like decision-making strategy, as compared to the conventional rule-based method.
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Borovyk, O., und V. Kupelskiy. „ALGORITHMIC SUPPORT FOR SELECTING OPTIMAL TRAFFIC ROUTE OF MOTOR CONVOY OF RAPID REACTION BORDER COMMAND POST“. Collection of scientific works of the Military Institute of Kyiv National Taras Shevchenko University, Nr. 64 (2019): 25–35. http://dx.doi.org/10.17721/2519-481x/2019/64-03.
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The rapid response border commandant's office is a structural unit of the border detachment, designed to protect and strengthen the protection of a certain section of the state border, and must quickly redeploy its forces and assets. The success of the tasks assigned to the unit depends largely on the timeliness of arrival at the destination. Operational transportation of a significant amount of weapons, personnel and dissimilar cargoes on land is carried out using equipment. At the preparatory stage of the organization of transportation, the problem of forming the optimal composition of the convoy of equipment is solved. The existing road network provides a sufficiently large number of traffic routes between the starting and ending points. Moreover, this takes place even for insignificant distances between points of departure and destination. The specified conditions for multivariance in the selection. In addition, the choice of the route of movement depends on many auxiliary conditions: driver training, technical characteristics and reliability of vehicles, traffic safety, road and environmental conditions, distance and timing of transportation, and the like. Poor accounting of these factors in the aggregate may lead to the choice of an irrational route of movement, will not ensure the timely arrival of the unit at the destination, and may lead to the failure to fulfill certain tasks. Therefore, the task of choosing the optimal route of movement of the column of equipment is relevant. At the substantive level, the task looks like the justification of the mathematical model for choosing the optimal route for the column of equipment, if the criterion of optimality is minimizing the time it takes to move from the starting point to the destination. The authors formed a mathematical model of the given problem, proposed an algorithm for its solution for three cases: discrete-stochastic, discretely-determined and continuously-indefinite, and the corresponding software was developed. The choice of routes is carried out for three options, taking into account the fact that the change in the weights of the ribs can be carried out: at times when the column is at a certain vertex of the graph, and the update of the matrix of weights is carried out precisely at these moments. This is the case when a decision on the further route of movement is formed at the road branching points, taking into account the situation, the status of individual sections changes dynamically and data for which appears periodically; at times when the column is at a certain vertex of the graph, and for these moments, the matrix of weights that will occur when the column hits the vertex are known in advance. This is the case when a decision on the route of movement can be formed at the beginning of the movement, taking into account the known situation on the state of the roads, dynamically change, but data on which can be taken into account in advance; randomly depending on the speed of the column at a fixed point in time for which the column speed function is known.
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Kalashnyk, Nataliya, Eric Salomon, Sung Hwan Mun, Jaehoon Jung, Luca Giovanelli, Thierry Angot, Frédéric Dumur, Didier Gigmes und Sylvain Clair. „The Orientation of Silver Surfaces Drives the Reactivity and the Selectivity in Homo-Coupling Reactions“. ChemPhysChem 19, Nr. 15 (04.06.2018): 1802–8. http://dx.doi.org/10.1002/cphc.201800406.
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Pallas, Florian, Lisa E. Bolton und Lara Lobschat. „Shifting the Blame“. Journal of Service Research 21, Nr. 3 (05.02.2018): 302–18. http://dx.doi.org/10.1177/1094670518755314.
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The proliferation of surcharges in service pricing raises theoretical and pragmatic questions regarding their impact on consumers. This research investigates how surcharges influence consumer responses to a service price increase. We propose that various kinds of surcharge information act in concert to drive blame attributions for a price increase: Internal (vs. external) surcharges increase blame attributions and minimize the influence of other drivers captured in surcharge information such as temporal stability, surcharge benefit, and more than one kind of surcharge. In comparison to all-inclusive pricing, we find that (i) surcharge pricing is detrimental to service firms when surcharges cue internal locus of causality, regardless of the temporal stability or surcharge benefit, whereas (ii) surcharge pricing is beneficial when surcharges cue external locus of causality, particularly when the surcharges are permanent and high benefit; (iii) consumers are more sensitive to increases in the magnitude of internal (vs. external) surcharges; and (iv) in the case of mixed surcharges, internal surcharges are more prominent and minimize the buffering effect of adding external surcharges. Based on our findings, we make recommendations to managers on the optimal design of surcharge pricing to mitigate negative blame reactions when communicating service price increases to consumers.
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Williamson, Deborah A., Glen P. Carter und Benjamin P. Howden. „Current and Emerging Topical Antibacterials and Antiseptics: Agents, Action, and Resistance Patterns“. Clinical Microbiology Reviews 30, Nr. 3 (07.06.2017): 827–60. http://dx.doi.org/10.1128/cmr.00112-16.
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SUMMARYBacterial skin infections represent some of the most common infectious diseases globally. Prevention and treatment of skin infections can involve application of a topical antimicrobial, which may be an antibiotic (such as mupirocin or fusidic acid) or an antiseptic (such as chlorhexidine or alcohol). However, there is limited evidence to support the widespread prophylactic or therapeutic use of topical agents. Challenges involved in the use of topical antimicrobials include increasing rates of bacterial resistance, local hypersensitivity reactions (particularly to older agents, such as bacitracin), and concerns about the indiscriminate use of antiseptics potentially coselecting for antibiotic resistance. We review the evidence for the major clinical uses of topical antibiotics and antiseptics. In addition, we review the mechanisms of action of common topical agents and define the clinical and molecular epidemiology of antimicrobial resistance in these agents. Moreover, we review the potential use of newer and emerging agents, such as retapamulin and ebselen, and discuss the role of antiseptic agents in preventing bacterial skin infections. A comprehensive understanding of the clinical efficacy and drivers of resistance to topical agents will inform the optimal use of these agents to preserve their activity in the future.
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Kaczmarek, Wojciech, Jarosław Panasiuk, Szymon Borys, Aneta Pobudkowska und Mikołaj Majsterek. „Analysis of the Kinetics of Swimming Pool Water Reaction in Analytical Device Reproducing Its Circulation on a Small Scale“. Sensors 20, Nr. 17 (26.08.2020): 4820. http://dx.doi.org/10.3390/s20174820.
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The most common cause of diseases in swimming pools is the lack of sanitary control of water quality; water may contain microbiological and chemical contaminants. Among the people most at risk of infection are children, pregnant women, and immunocompromised people. The origin of the problem is a need to develop a system that can predict the formation of chlorine water disinfection by-products, such as trihalomethanes (THMs). THMs are volatile organic compounds from the group of alkyl halides, carcinogenic, mutagenic, teratogenic, and bioaccumulating. Long-term exposure, even to low concentrations of THM in water and air, may result in damage to the liver, kidneys, thyroid gland, or nervous system. This article focuses on analysis of the kinetics of swimming pool water reaction in analytical device reproducing its circulation on a small scale. The designed and constructed analytical device is based on the SIMATIC S7-1200 PLC driver of SIEMENS Company. The HMI KPT panel of SIEMENS Company enables monitoring the process and control individual elements of device. Value of the reaction rate constant of free chlorine decomposition gives us qualitative information about water quality, it is also strictly connected to the kinetics of the reaction. Based on the experiment results, the value of reaction rate constant was determined as a linear change of the natural logarithm of free chlorine concentration over time. The experimental value of activation energy based on the directional coefficient is equal to 76.0 [kJ×mol−1]. These results indicate that changing water temperature does not cause any changes in the reaction rate, while it still affects the value of the reaction rate constant. Using the analytical device, it is possible to constantly monitor the values of reaction rate constant and activation energy, which can be used to develop a new way to assess pool water quality.
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Heiles, Sven. „Advanced tandem mass spectrometry in metabolomics and lipidomics—methods and applications“. Analytical and Bioanalytical Chemistry 413, Nr. 24 (18.06.2021): 5927–48. http://dx.doi.org/10.1007/s00216-021-03425-1.
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AbstractMetabolomics and lipidomics are new drivers of the omics era as molecular signatures and selected analytes allow phenotypic characterization and serve as biomarkers, respectively. The growing capabilities of untargeted and targeted workflows, which primarily rely on mass spectrometric platforms, enable extensive charting or identification of bioactive metabolites and lipids. Structural annotation of these compounds is key in order to link specific molecular entities to defined biochemical functions or phenotypes. Tandem mass spectrometry (MS), first and foremost collision-induced dissociation (CID), is the method of choice to unveil structural details of metabolites and lipids. But CID fragment ions are often not sufficient to fully characterize analytes. Therefore, recent years have seen a surge in alternative tandem MS methodologies that aim to offer full structural characterization of metabolites and lipids. In this article, principles, capabilities, drawbacks, and first applications of these “advanced tandem mass spectrometry” strategies will be critically reviewed. This includes tandem MS methods that are based on electrons, photons, and ion/molecule, as well as ion/ion reactions, combining tandem MS with concepts from optical spectroscopy and making use of derivatization strategies. In the final sections of this review, the first applications of these methodologies in combination with liquid chromatography or mass spectrometry imaging are highlighted and future perspectives for research in metabolomics and lipidomics are discussed. Graphical abstract
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Minschwaner, K., G. L. Manney, S. H. Wang und R. S. Harwood. „Hydroxyl in the stratosphere and mesosphere – Part 1: Diurnal variability“. Atmospheric Chemistry and Physics 11, Nr. 3 (02.02.2011): 955–62. http://dx.doi.org/10.5194/acp-11-955-2011.
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Abstract. Diurnal variations in hydroxyl (OH) in the stratosphere and mesosphere are analyzed using measurements from the Aura Microwave Limb Sounder (MLS). The primary driver for OH diurnal variations is the ultraviolet actinic flux that initiates the photochemical production of reactive hydrogen species. The magnitude of this flux is governed largely by changes in solar zenith angle (SZA) throughout the day, and OH diurnal variations are well approximated by an exponential function of the secant of SZA. Measured OH concentrations are fit to a function of the form exp[−βsec(SZA)], where the parameter β is a function of altitude. We examine the magnitude of β and show that it is related to the optical depths of ultraviolet absorption by ozone and molecular oxygen. Values of β from SLIMCAT model simulations show the same vertical structure as those from MLS and the average level of agreement between model and measurements is 6%. The vertical profile of β from MLS can be represented by a simple analytic formulation involving the ozone and water vapor photodissociation rates. This formulation is used to infer the altitude dependence of the primary production mechanisms for OH: the reaction of excited-state atomic oxygen with water vapor versus the direct photodissociation of water vapor.
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Occhipinti, Annalisa, Filmon Eyassu, Thahira J. Rahman, Pattanathu K. S. M. Rahman und Claudio Angione. „In silico engineering ofPseudomonasmetabolism reveals new biomarkers for increased biosurfactant production“. PeerJ 6 (17.12.2018): e6046. http://dx.doi.org/10.7717/peerj.6046.
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BackgroundRhamnolipids, biosurfactants with a wide range of biomedical applications, are amphiphilic molecules produced on the surfaces of or excreted extracellularly by bacteria includingPseudomonas aeruginosa. However,Pseudomonas putidais a non-pathogenic model organism with greater metabolic versatility and potential for industrial applications.MethodsWe investigate in silico the metabolic capabilities ofP. putidafor rhamnolipids biosynthesis using statistical, metabolic and synthetic engineering approaches after introducing key genes (RhlAandRhlB) fromP. aeruginosainto a genome-scale model ofP. putida. This pipeline combines machine learning methods with multi-omic modelling, and drives the engineeredP. putidamodel toward an optimal production and export of rhamnolipids out of the membrane.ResultsWe identify a substantial increase in synthesis of rhamnolipids by the engineered model compared to the control model. We apply statistical and machine learning techniques on the metabolic reaction rates to identify distinct features on the structure of the variables and individual components driving the variation of growth and rhamnolipids production. We finally provide a computational framework for integrating multi-omics data and identifying latent pathways and genes for the production of rhamnolipids inP. putida.ConclusionsWe anticipate that our results will provide a versatile methodology for integrating multi-omics data for topological and functional analysis ofP. putidatoward maximization of biosurfactant production.
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France, J. L., M. D. King, M. M. Frey, J. Erbland, G. Picard, A. MacArthur und J. Savarino. „Snow optical properties at Dome C, Antarctica – implications for snow emissions and snow chemistry of reactive nitrogen“. Atmospheric Chemistry and Physics Discussions 11, Nr. 4 (18.04.2011): 11959–93. http://dx.doi.org/10.5194/acpd-11-11959-2011.
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Abstract. Measurements of $e$-folding depth, nadir reflectivity and stratigraphy of the snowpack around Concordia station (Dome C, 75.10° S, 123.31° E) were undertaken and used to determine wavelength dependent coefficients (350 nm to 550 nm) for light scattering and absorption and to calculate potential fluxes of nitrogen dioxide (NO2) from the snowpack due to nitrate photolysis within the snowpack. The stratigraphy of the top 80 cm of Dome C snowpack generally consists of three main layers: a surface of soft windpack (not ubiquitous), a hard windpack and a hoar-like layer beneath the windpack(s). The $e$-folding depths are ~10 cm for the two windpack layers and ~20 cm for the hoar-like layer for solar radiation at a wavelength of 400 nm, about a factor 2–4 larger than previous model estimates for South Pole. Depth integrated photochemical reaction rates of nitrate photolysis in the Dome C snowpack were calculated to give molecular fluxes of NO2 of 5.3×1012 molecules m−2 s−1, 2.3×1012 molecules m−2 s−1 and 8×1011 molecules m−2 s−1 for solar zenith angles of 60°, 70° and 80° respectively for clear sky conditions using the TUV-snow radiative-transfer model. Depending upon the snowpack stratigraphy, a minimum of 85% of the NO2 originates from within the top 20 cm of the Dome C snowpack. It is found that on a multi-annual scale, nitrate photolysis can remove up to 80% of nitrate from surface snow, confirming independent isotopic evidence that photolysis is an important driver of nitrate loss occurring in the EAIS snowpack. However, the model cannot account for the total observed nitrate loss of 90–95% or the shape of the observed nitrate depth profile. A more complete model will need to include also physical processes such as evaporation, re-deposition or diffusion between the quasi-liquid layer on snow grains and firn air to account for the discrepancies.
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Guan, Cassandra Xin. „Critique of Flowers: The Exigency of Life in the Era of Its Technical Reproducibility“. October, Nr. 175 (2021): 26–69. http://dx.doi.org/10.1162/octo_a_00415.
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Abstract Need, as an epigenetic concept, originated with Jean-Baptiste Lamarck, for whom it referred to the pressure of circumstances that compel animals to develop new organs in the course of evolution. It reappeared in twentieth-century science as the somatic disequilibrium that Sigmund Freud, following Psycho-Lamarckian biologists, first called “the need of life” (die Not des Lebens) and then “the drives” (Trieb). The invention of time-lapse cinematography around 1900, initially as an optical instrument in the experimental study of plant physiology, visibly enlarged the epigenetic paradigm: Plants were suddenly perceived as agential beings, attached to the physical environment not by their roots, but rather by their needs and activities. The disquieting impression of responsive behavior became the selling point of the BASF-commissioned nitrogen-fertilizer commercial Miracle of Flowers (1926), a film celebrated by Rudolf Arnheim as “the most fantastic, thrilling, and beautiful picture ever made.” This article interrogates the sovereignty of need in epigenesis, using Miracle of Flowers as a case study. Through a close reading of the animal-like organisms in this film and the emotional reactions they elicited, need is reimagined as a maladaptive force embodied in technical media that tethers unhappy individuals to punishing environments.
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Inamdar, Swaleha, Liselotte Tinel, Rosie Chance, Lucy J. Carpenter, Prabhakaran Sabu, Racheal Chacko, Sarat C. Tripathy et al. „Estimation of reactive inorganic iodine fluxes in the Indian and Southern Ocean marine boundary layer“. Atmospheric Chemistry and Physics 20, Nr. 20 (26.10.2020): 12093–114. http://dx.doi.org/10.5194/acp-20-12093-2020.
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Abstract. Iodine chemistry has noteworthy impacts on the oxidising capacity of the marine boundary layer (MBL) through the depletion of ozone (O3) and changes to HOx (OH∕HO2) and NOx (NO∕NO2) ratios. Hitherto, studies have shown that the reaction of atmospheric O3 with surface seawater iodide (I−) contributes to the flux of iodine species into the MBL mainly as hypoiodous acid (HOI) and molecular iodine (I2). Here, we present the first concomitant observations of iodine oxide (IO), O3 in the gas phase, and sea surface iodide concentrations. The results from three field campaigns in the Indian Ocean and the Southern Ocean during 2015–2017 are used to compute reactive iodine fluxes in the MBL. Observations of atmospheric IO by multi-axis differential optical absorption spectroscopy (MAX-DOAS) show active iodine chemistry in this environment, with IO values up to 1 pptv (parts per trillion by volume) below latitudes of 40∘ S. In order to compute the sea-to-air iodine flux supporting this chemistry, we compare previously established global sea surface iodide parameterisations with new region-specific parameterisations based on the new iodide observations. This study shows that regional changes in salinity and sea surface temperature play a role in surface seawater iodide estimation. Sea–air fluxes of HOI and I2, calculated from the atmospheric ozone and seawater iodide concentrations (observed and predicted), failed to adequately explain the detected IO in this region. This discrepancy highlights the need to measure direct fluxes of inorganic and organic iodine species in the marine environment. Amongst other potential drivers of reactive iodine chemistry investigated, chlorophyll a showed a significant correlation with atmospheric IO (R=0.7 above the 99 % significance level) to the north of the polar front. This correlation might be indicative of a biogenic control on iodine sources in this region.
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Burtsev, V. A., S. Y. Gus'kov, V. B. Rozanov, D. V. Il'In, A. A. Levkovsky, V. E. Sherman, Y. N. Starbunov und N. V. Zmitrenko. „Mathematical modeling of the thermonuclear burning in DHe3 targets with D-T ignition“. Laser and Particle Beams 11, Nr. 4 (Dezember 1993): 669–77. http://dx.doi.org/10.1017/s026303460000642x.
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It is shown that there is a principal possibility of effective burning with gain G > 200 of ecologically clean DHe3 fuel in reactor-type targets without increase of driver energy. The proper target consists of DHe3 fuel and a D-T ignitor with a central hot spark. Under proper conditions, the D-T burning wave reaches the DHe3 range with the temperature sufficient for ignition of DHe3 plasma. The simulation was carried out by means of TERA code based upon self-consistent solution of a kinetic equations system for products of primary and secondary thermonuclear reactions by the Monte Carlo method and a hydrodynamic equations system.
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Farhang Mehr, Ali, und Irem Y. Tumer. „Risk-Based Decision-Making for Managing Resources During the Design of Complex Space Exploration Systems“. Journal of Mechanical Design 128, Nr. 4 (29.01.2006): 1014–22. http://dx.doi.org/10.1115/1.2205868.
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Complex space exploration systems are often designed in collaborative engineering environments where requirements and design decisions by various subsystem engineers have a great impact on the overall risk of the mission. As a result, the system-level management should allocate risk mitigation resources (e.g., capital to place additional sensors or to improve the current technology) among various risk elements such that the main objectives of the system are achieved as closely as possible. Minimizing risk has been long accepted as one of the major drivers for system-level decisions and particularly resource management. In this context, Risk-Based Decision Making refers to a process that allocates resources in such a way that the expected risk of the overall system is minimized. This paper presents a new risk-based design decision-making method, referred to as Risk and Uncertainty Based Concurrent Integrated Design Methodology or RUBIC Design Methodology for short. The new approach is based on concepts from portfolio optimization theory and continuous resource management, extended to provide a mathematical rigor for risk-based decision-making during the design of complex space exploration systems. The RUBIC design method is based on the idea that a unit of resource, allocated to mitigate a certain risk in the system, contributes to the overall system risk reduction in the following two ways: (1) by mitigating that particular risk; and (2) by impacting other risk elements in the system (i.e., the correlation among various risk elements). RUBIC then provides a probabilistic framework for reducing the expected risk of the final system via optimal allocation of available risk-mitigation resources. The application of the proposed approach is demonstrated using a satellite reaction wheel example.
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Das, Anutosh, Sumaia Kashem und Mahamudul Hasan. „Using market mechanism to stimulate sustainable use of the non-renewable environmental resource (groundwater) in Barind Tract of Bangladesh“. HKIE Transactions 28, Nr. 1 (15.04.2021): 39–48. http://dx.doi.org/10.33430/v28n1thie-2020-0036.
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Agriculture, the main economic driver of Barind Tract, is highly dependent on groundwater for surface water paucity in the area. Notwithstanding, farmers use water capriciously due to its low price that makes a substantial drop in the water table. In this context, the research attempts to determine a market-based water pricing mechanism to encourage an optimal use of the scarce non-renewable resource. Required data was collected by questionnaire survey, Focus Group Discussion (FGD), Contingent Valuation Method, expert-opinion survey and subsequent literature works. The results reveal that depletion level has arrived at 20, 11, 7.5 feet in high, mid and low tract respectively over the last 22 years, which results in a number of economic-environmental externalities in the area. The research monetarily evaluated the cost of externalities and incorporated it with the marginal cost of extraction to increase efficiency of an existing pricing system. Regarding human reaction to price elasticity, the new price can be a reliable attempt to reduce an overconsumption pattern of water. Quantity of consumed water can be reduced to 14190.4 m3, 17759.59 m3 and 38510.6 m3 in a year in high, mid and low tract area respectively with its implementation. The research will serve as an initiative to conserve the valuable groundwater resource for future generations by managing consumer practice.
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Jiang, Luo, Jie Ji, Yue Ren, Hong Wang und Yanjun Huang. „Risk Modeling and Quantification of a Platoon in Mixed Traffic Based on the Mass-Spring-Damper Model“. Journal of Advanced Transportation 2020 (08.07.2020): 1–12. http://dx.doi.org/10.1155/2020/7475682.
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Connected and automated vehicle (CAV) technologies have great potential to improve road safety. However, an emerging type of mixed traffic flow with human-driven vehicles (HDVs) and CAVs has also arisen in recent years. To improve the overall safety of this mixed traffic flow, a novel car-following model is proposed to control the driving behaviors of the above two types of vehicles in a platoon from the perspective of a mechanical system, mass-spring-damper (MSD) system. Furthermore, a quantitative index is proposed by incorporating the psychological field theory into the MSD model. The errors of spacing and speed in the car-following processes can be expressed as the accumulation of the virtual total energy, and the magnitude of the energy is used to reflect the danger level of vehicles in the mixed platoon. At the same time, the optimization model of minimum total energy is solved under the constraints of vehicle dynamics and the mechanical characteristics of the MSD system, and the optimal solutions are used as the parameters of the MSD car-following model. Finally, a mixed platoon composed of 3 CAVs and 2 HDVs without performing lane changing is tested using the driver-in-the-loop test platform. The test results show that, in the mixed platoon, CAVs can optimally adjust the intervehicle spacing by making full use of the braking distance, which also provides sufficient reaction time for the driver of HDV to avoid rear-end collisions. Furthermore, in the early stage of the emergency braking, the spacing error is the dominant factor influencing the car-following behaviors, but in the later stage of emergency braking, the speed error becomes the decisive factor of the car-following behaviors. These results indicate that the proposed car-following model and quantitative index are of great significance for improving the overall safety of the mixed traffic flow with CAVs and HDVs.