Crash Analysis of Work Zone Lane Closures with Left-Hand Merge and Downstream Lane Shift

The Arkansas State Highway and Transportation Department (AHTD) began the Interstate Rehabilitation Program (IRP) in the spring of 2000 that ultimately rebuilt approximately 380 miles, or 60% of Arkansas' 655-mile Interstate system. While these projects were underway, a new lane closure method, the "Iowa weave," or lane closure with a left-hand merge and lane shift, was introduced to AHTD to effectively save time ensuring that these IRP projects were completed on schedule. Contractors on the projects used the Iowa weave at least 50% of the time for each of the projects. The settings between the Iowa weave and the conventional right-lane closure were rotated on a periodic basis depending on the work to be completed on each side of the lane. Construction officials in AHTD agreed that the use of the Iowa weave helped them to complete the rehabilitation program on time and improved traffic safety, as no major concerns were noted due to this new technique. However, the crash analysis of this weaving pattern as opposed to the conventional right-lane closure has not been assessed to determine which lane closure strategy has an advantage on the basis of actual crash experience. This research examined the work zone crashes in both of the lane closure settings by assessing them with a set of independent variables that have been known to be the factors that influence work zone crashes. In order to properly assess the comparison between the two lane closure strategies, the following primary research objectives were pursued: Examination of crash experience results from the two traffic control methods, and Reexamination of the advantages and disadvantages of the Iowa weave method as compared to the conventional right-lane closure. This study analyzed the crash data between January 1, 2000 and December 31, 2005 on the characteristics of lane closure strategies in Arkansas. The findings of the analyses were organized by: 1) Raw number of crashes (Pearson chi-square and One-Way ANOVA tests); 2) Crash rates (paired t-test); and Crash severity (binary logistic regression modeling). The analysis results of this study may be used for DOTs to reference the impressive rehabilitation work that the AHTD has completed by incorporating the use of the Iowa weave. The results of the statistical analyses showed that there was approximately a 30 percent reduction in crash rate when the Iowa weave configuration was used. Nonetheless, the final results of the logistic regression model found that the safety advantages between the Iowa weave and conventional right-lane closure in changing crash severity were not statistically significant. Traffic volume was found to be the parameter that most significantly affected crash severity in the logistic regression model. Also, the effects of lighting conditions and intersecting streets on the severity of crashes were found to be insignificant

Optimal Power Allocation for Two-Way Decode-and-Forward OFDM Relay Networks

This paper presents a novel two-way decode-and-forward (DF) relay strategy for Orthogonal Frequency Division Multiplexing (OFDM) relay networks. This DF relay strategy employs multi-subcarrier joint channel coding to leverage frequency selective fading, and thus can achieve a higher data rate than the conventional per-subcarrier DF relay strategies. We further propose a low-complexity, optimal power allocation strategy to maximize the data rate of the proposed relay strategy. Simulation results suggest that our strategy obtains a substantial gain over the per-subcarrier DF relay strategies, and also outperforms the amplify-and-forward (AF) relay strategy in a wide signal-to-noise-ratio (SNR) region.Comment: 5 pages, 2 figures, accepted by IEEE ICC 201

Integration of an On-Axis General Sun-Tracking Formula in the Algorithm of an Open-Loop Sun-Tracking System

A novel on-axis general sun-tracking formula has been integrated in the algorithm of an open-loop sun-tracking system in order to track the sun accurately and cost effectively. Sun-tracking errors due to installation defects of the 25 m2 prototype solar concentrator have been analyzed from recorded solar images with the use of a CCD camera. With the recorded data, misaligned angles from ideal azimuth-elevation axes have been determined and corrected by a straightforward changing of the parameters' values in the general formula of the tracking algorithm to improve the tracking accuracy to 2.99 mrad, which falls below the encoder resolution limit of 4.13 mrad

Evidence for Urban–Rural Disparity in Temperature–Mortality Relationships in Zhejiang Province, China

Background: Temperature-related mortality risks have mostly been studied in urban areas, with limited evidence for urban–rural differences in the temperature impacts on health outcomes. Objectives: We investigated whether temperature–mortality relationships vary between urban and rural counties in China. Methods: We collected daily data on 1 km gridded temperature and mortality in 89 counties of Zhejiang Province, China, for 2009 and 2015. We first performed a two-stage analysis to estimate the temperature effects on mortality in urban and rural counties. Second, we performed meta-regression to investigate the modifying effect of the urbanization level. Stratified analyses were performed by all-cause, nonaccidental (stratified by age and sex), cardiopulmonary, cardiovascular, and respiratory mortality. We also calculated the fraction of mortality and number of deaths attributable to nonoptimum temperatures associated with both cold and heat components. The potential sources of the urban–rural differences were explored using meta-regression with county-level characteristics. Results: Increased mortality risks were associated with low and high temperatures in both rural and urban areas, but rural counties had higher relative risks (RRs), attributable fractions of mortality, and attributable death counts than urban counties. The urban–rural disparity was apparent for cold (first percentile relative to minimum mortality temperature), with an RR of 1.47 [95% confidence interval (CI): 1.32, 1.62] associated with all-cause mortality for urban counties, and 1.98 (95% CI: 1.87, 2.10) for rural counties. Among the potential sources of the urban–rural disparity are age structure, education, GDP, health care services, air conditioners, and occupation types. Conclusions: Rural residents are more sensitive to both cold and hot temperatures than urban residents in Zhejiang Province, China, particularly the elderly. The findings suggest past studies using exposure–response functions derived from urban areas may underestimate the mortality burden for the population as a whole. The public health agencies aimed at controlling temperature-related mortality should develop area-specific strategies, such as to reduce the urban–rural gaps in access to health care and awareness of risk prevention. Future projections on climate health impacts should consider the urban–rural disparity in mortality risks

Pathway using WUDAPT's Digital Synthetic City tool towards generating urban canopy parameters for multi-scale urban atmospheric modeling

The WUDAPT (World Urban Database and Access Portal Tools project goal is to capture consistent information on urban form and function for cities worldwide that can support urban weather, climate, hydrology and air quality modeling. These data are provided as urban canopy parameters (UCPs) as used by weather, climate and air quality models to simulate the effects of urban surfaces on the overlying atmosphere. Information is stored with different levels of detail (LOD). With higher LOD greater spatial precision is provided. At the lowest LOD, Local Climate Zones(LCZ) with nominal UCP ranges is provided (order 100 m or more). To describe the spatial heterogeneity present in cities with great specificity at different urban scales we introduce the Digital Synthetic City (DSC) tool to generate UCPs at any desired scale meeting the fit-for-purpose goal of WUDAPT. 3D building and road elements of entire city landscapes are simulated based on readily available data. Comparisons with real-world urban data are very encouraging. It is customized (C-DSC) to incorporate each city's unique building morphologies based on unique types, variations and spatial distribution of building typologies, architecture features, construction materials and distribution of green and pervious surfaces. The C-DSC uses crowdsourcing methods and sampling within city Testbeds from around the world. UCP data can be computed from synthetic images at selected grid sizes and stored such that the coded string provides UCP values for individual grid cells

Long Span DNA Paired-End-Tag (DNA-PET) Sequencing Strategy for the Interrogation of Genomic Structural Mutations and Fusion-Point-Guided Reconstruction of Amplicons

10.1371/journal.pone.0046152PLoS ONE79

First Sagittarius A* Event Horizon Telescope Results. VII. Polarization of the Ring

The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A* (Sgr A*), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μas and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M ≈ 4 × 106 M ⊙. From these observations, we present the first resolved linear and circular polarimetric images of Sgr A*. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%–10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication

Molecular-level methylcellulose/mxene hybrids with greatly enhanced electrochemical actuation

Ti₃C₂Tₓ MXene film is promising for electrochemical actuators due to its high electrical conductivity and volumetric capacitance. However, its actuation performance is limited by the slow ion diffusion through the film and poor mechanical property in aqueous electrolytes. Here, molecular-level methylcellulose (MC)/MXene hybrid films are assembled with obviously enlarged layer distance, improved wet strength, and ambient stability. The hybrid films show significantly higher in-plane actuation strain in a liquid electrolyte. Based on direct strain measurements, in situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) analyses, the actuation enhancement can be ascribed to the enlarged layer distance allowing more water and ions to be intercalated/de-intercalated and MC-induced sliding of MXene sheets. The assembled soft actuator has a high Young's modulus of 1.93 GPa and can be operated in air, generating a peak-to-peak strain difference up to 0.541% under a triangular wave voltage of ±1 V and a blocking force of 4.7 times its own weight.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThe authors acknowledge the funding provided by Ministry of Education under project no. 2020-T1-001-165. Part of this work is also supported by grant no. NRF2020-NRF-ANR102 MEACT under the National Research Foundation, Singapore

Ionic covalent organic framework based electrolyte for fast-response ultra-low voltage electrochemical actuators

Electrically activated soft actuators with large deformability are important for soft robotics but enhancing durability and efficiency of electrochemical actuators is challenging. Herein, we demonstrate that the actuation performance of an ionic two-dimensional covalent-organic framework based electrochemical actuator is improved through the ordered pore structure of opening up efficient ion transport routes. Specifically, the actuator shows a large peak to peak displacement (9.3 mm, ±0.5 V, 1 Hz), a fast-response time to reach equilibrium-bending (~1 s), a correspondingly high bending strain difference (0.38%), a broad response frequency (0.1-20 Hz) and excellent durability (>99%) after 23,000 cycles. The present study ascertains the functionality of soft electrolyte as bionic artificial actuators while providing ideas for expanding the limits in applications for robots.Ministry of Education (MOE)National Research Foundation (NRF)Published versionWe acknowledge financial support from Singapore Ministry of Education Tier 1, RG63/ 20 (2020-T1-001-165) and the National Research Foundation, Prime Minister’s Office, Singapore, under its Campus for Research Excellence and Technological Enterprise (CREATE) program

Self-powered and light-adaptable stretchable electrochromic display

A stretchable electrochromic display with a self-powered feature is an attractive concept in addressing the demands of information visualization and interaction without an external power supply for next-generation wearable and portable electronics. Herein, a self-powered stretchable electrochromic display is proposed for the first time, with WO3 on the stretchable conductor as the electrochromic electrode integrated in parallel with the Zn/carbon electrodes and topped with a ZnCl2-based organohydrogel. This geometrically designed electrochromic device can be self-colored by the chemical potential gap between WO3/Zn electrodes. The self-bleaching process caused by the oxidation of the reduced WO3 electrode is facilitated by the leakage current between the WO3/carbon electrodes. In this constructed self-powered system, the electrochromic electrode shows reversible coloring/bleaching performance up to 50% strain and maintains favorable stability with power-free reversible electrochemical switching for 400 cycles. Optical contrast retention at 81% is maintained for 200 stretching/recovery cycles. The prepared device combined with a phosphorescent substrate is demonstrated as a light-adaptable stretchable display, where the “on/off” states of the display are shown in both bright and dark conditions without power consumption. This work provides broad application prospects for futuristic multifunctional stretchable and portable display electronics.Ministry of Education (MOE)This work was supported by funding from the Ministry of Education (MOE) Singapore, AcRF Tier 1, Project No. RG64/21 and National Natural Science Foundation of China (No. 51902250). The author W.W. thanks the support from the China Scholarship Council (Grant No 202006280507) and Basic Scientific Research of Xi’an Jiaotong University (Grant No. xzy022022028)