In this paper, we introduce the Vehicle Routing Problem with Flexible Time Windows (VRPFlexTW), in which vehicles are allowed to deviate from customer time windows by a given tolerance. This ...flexibility enables savings in the operational costs of carriers, since customers may be served before and after the earliest and latest time window bounds, respectively. However, as time window deviations are undesired from a customer service perspective, a penalty proportional to these deviations is accounted for in the objective function. We develop a solution procedure, in which feasible vehicle routes are constructed via a tabu search algorithm. Furthermore, we propose a linear programming model to handle the detailed scheduling of customer visits for given routes. We validate our solution procedure by a number of Vehicle Routing Problem with Time Windows (VRPTW) benchmark instances. We highlight the costs involved in integrating flexibility in time windows and underline the advantages of the VRPFlexTW, when compared to the VRPTW.
Newly born zinc‐anode‐based electrochromic devices (ZECDs), incorporating electrochromic and energy storage functions in a single transparent platform, represent the most promising technology for ...next‐generation transparent electronics. As the existing ZECDs are limited by opaque zinc anodes, the key focus should be on the development of transparent zinc anodes. Here, the first demonstration of a flexible transparent zinc‐mesh electrode is reported for a ZECD window that yields a remarkable electrochromic performance in an 80 cm2 device, including rapid switching times (3.6 and 2.5 s for the coloration and bleaching processes, respectively), a high optical contrast (67.2%), and an excellent coloration efficiency (131.5 cm2 C−1). It is also demonstrated that such ZECDs are perfectly suited for solar‐charging smart windows as they inherently address the solar intermittency issue. These windows can be colored via solar charging during the day, and they can be bleached during the night by supplying electrical energy to electronic devices. The ZECD smart window platform can be scaled to a large area while retaining its excellent electrochromic characteristics. These findings represent a new technology for solar‐charging windows and open new opportunities for the development of next‐generation transparent batteries.
The first example of flexible transparent zinc‐mesh electrodes is demonstrated for
assembly of large‐scale Zn‐anode‐based electrochromic windows, and solar‐charging smart windows with sunlight‐intermittency issues perfectly addressed are presented. These findings facilitate new opportunities for the development of next‐generation transparent electrochemical devices.
The control performance of myoelectric prostheses would not only depend on the feature extraction and classification algorithms but also on interactions of dynamic window-based hyperparameters (WBHP) ...used to construct input signals. However, the relationship between these hyperparameters and how they influence the performance of the convolutional neural networks (CNNs) during motor intent decoding has not been studied. Therefore, we investigated the impact of various combinations of WBHP (window length and overlap) employed for the construction of raw two-dimensional (2-D) surface electromyogram (sEMG) signals on the performance of CNNs when used for motion intent decoding. Moreover, we examined the relationship between the window length of the 2-D sEMG and three commonly used CNN kernel sizes. To ensure high confidence in the findings, we implemented three CNNs, which are variants of the existing models, and a newly proposed CNN model. Experimental analysis was conducted using three distinct benchmark databases, two from upper limb amputees and one from able-bodied subjects. The results demonstrate that the performance of the CNNs improved as the overlap between consecutively generated 2-D signals increased, with 75% overlap yielding the optimal improvement by 12.62% accuracy and 39.60% F1-score compared to no overlap. Moreover, the CNNs performance was better for kernel size of seven than three and five across the databases. For the first time, we have established with multiple evidence that WBHP would substantially impact the decoding outcome and computational complexity of deep neural networks, and we anticipate that this may spur positive advancement in myoelectric control and related fields.
Vanadium dioxide, which has been demonstrated as negative differential thermal emissivity materials for emissivity engineering application, is regarded as the most important and promising material ...for adaptive infrared camouflage. This study describes the synthesis and characterization of high purity, uniform VO2 nanopowders by a single-step hydrothermal method and their thermal polymorphism. A dramatic phase transition of the monoclinic VO2 nanopowders to a tetragonal phase upon heating and the accompanying change in the IR emissivity are demonstrated. Importantly, we demonstrate the tunability of the infrared radiation intensity of VO2 nanopowders in both mid- and far-IR thermal atmospheric windows, for the first time. The structural transition is analyzed by variable temperature XRD and temperature-dependent Raman spectroscopy. Furthermore, an unexpected structural change in the same region of the sample was observed in a transmission electron microscope, which provides a direct mechanistic understanding of the infrared emissivity variation. Our study makes a significant contribution to the state-of-the-art in thermal camouflaging, because this study demonstrates that the VO2 nanopowders can be extremely promising camouflage materials in the area of adaptive infrared camouflage technology both in the far-infrared and mid-infrared regions and the material is suitable for substrates with large surface areas and/or complex morphologies.
Display omitted
•Uniform VO2 nanopowders are synthesized by a single-step hydrothermal method.•The phase transition is analyzed by variable temperature XRD and Raman spectra.•The tunable emissivity in both thermal atmospheric windows is obtained.•An unexpected structural change in the same region of the sample is observed.
To reduce bird fatalities from millions of window collisions each year in North America, it is important to understand how design and landscape elements relate to collision risk. The current study ...extends prior research that found that buildings near ornamental pear trees (
) and buildings with mirrored windows significantly increased odds of collisions among eight buildings on the University of Utah campus in winter. The previous study found bird-friendly glass was not related to collision risk, although only one fatality occurred at two buildings with ORNILUX® ultraviolet (UV) or fritted windows. We reasoned that extending data collection to include fall might provide a better test of efficacy. We tested the following three hypotheses: (1) Buildings with mirrored windows would experience more collisions, replicating the original study; (2) the addition of fall migration data would reveal fewer collisions at the buildings with bird-friendly windows; (3) the danger of pear tree proximity would be heightened in winter, when fruit is ripe enough to appeal to frugivores, especially the Cedar Waxwings (
) that frequent these trees.
Trained observers monitored buildings three times per week in Fall (September 12 to October 27, 2019) and Winter (October 29, 2019 to January 24, 2020). Collisions were photographed and documented in the iNaturalist University of Utah Bird Window Collision Project.
There were 39 total collisions, from 0 to 14 per building
Using generalized estimating equations, buildings near pear trees had 3.33-fold increased odds, mirrored windows had 5.92-fold increased odds, and bird-friendly windows had an 84% lower odds (Odds ratio = 0.16) of bird window collisions when analyzed separately; all were statistically significant (
< 0.01). A test of all possible combinations of risk and protective factors revealed that the best fit model included pear trees (odds = 2.31) and mirrored windows (odds = 2.33). A separate analysis tested the pear tree by season interaction model; it yielded the deadliest combination, with 40-fold increased odds for buildings near pear trees in winter season.
This research provides the first peer-reviewed evidence found for the efficacy of bird-friendly fritted windows and ORNILUX ® UV windows in buildings. In addition, it replicated a study that established the dangers of mirrored windows and fruiting pear trees near buildings. These risks were especially dangerous to Cedar Waxwings, who constituted 62.2% of the identifiable window collision victims. This research highlights how building risks depend on window design, landscape choices, species, and season. If replicated, analyses of risk factors can help identify buildings that require mitigation to make existing windows less deadly. Results also support the installation of bird-friendly glass in new or renovated buildings to reduce fatalities.
Over the past decades, spring arrival and passage of most short‐ and medium‐distance migrating birds in the Northern Hemisphere have advanced. Changes in spring temperature at the passage or arrival ...area have been most frequently shown to be related to these changes in spring migration phenology. In most studies, preliminary assumptions are made on both the spatial location and the specific time frame of the weather influencing spring migration phenology. We performed a spatially explicit time‐window analysis of the effect of weather on mean spring passage dates of nine short‐ and medium‐distance passerines. We analysed data from standardized daily captures at the Helgoland (Germany) constant‐effort site, in combination with gridded daily temperature, precipitation and wind data from the NCEP data set over a 55‐year period (1960–2014), across the whole of West Europe and North Africa. Although we allowed for a time window of any length at any location, nevertheless incorporating various measures to avoid spurious correlations, time windows at the likely wintering or spring stopover grounds were almost exclusively selected as the best predicting variables (96%–100% of identified variables). The weather variables at the wintering and stopover grounds explain up to 77% of the interannual variability in spring passage. Yet, the response of spring migration phenology to weather at the winter or stopover areas does not fully explain the observed trends. Spring migration phenology is, hence, strongly driven by weather at the wintering and stopover grounds, but additional mechanisms are needed to fully explain the advancement of spring migration. Our results also clearly show that previously illustrated correlations, or the lack thereof, between spring migration phenology and weather at the passage or arrival location are due to spatio‐temporal correlations in the weather data. This spatial mismatch might have led to false conclusions, especially the further away the wintering or stopover sites are.
We performed a spatially explicit time‐window analysis of the effect of weather on mean spring passage dates at Helgoland (Germany) over a 55‐year period (1960–2014). Although we allowed for a time window of any length at any location, nevertheless incorporating various measures to avoid spurious correlations, time windows at the likely wintering or spring stopover grounds were almost exclusively selected as the best predicting variables, explaining up to 77% of the interannual variability in spring passage. Yet, the response of spring migration phenology to weather at the winter or stopover areas does not fully explain the observed trends.
The fast acquisition of heart rate (HR) is a challenge in noncontact vital sign detection using a Doppler radar system. Most of the previous studies use long-period time windows to guarantee a ...sufficient frequency spectrum resolution for HR measurement using the peak searching method on the frequency spectrum. For fast acquisition of HR, the length of the time window is less than 5 s and the accuracy is significantly degraded due to insufficient spectrum resolution. For vital sign detection using complex signal demodulation (CSD), measuring HR variation becomes a difficult job due to respiration harmonic interference and insufficient frequency spectrum resolution. In this paper, a time-window-variation technique is developed for fast acquisition of HR from short-period time windows and measuring HR variation using CSD. Experiments are performed on four human subjects under controlled laboratory conditions by a 5.8-GHz continuous-wave Doppler radar vital sign detection system. The HR measurement results within 2-5-s time windows are compared by applying a simple fast Fourier transform (FFT) and peak searching method, a 10-s sliding-time-window FFT method, and the proposed method. The proposed method achieves the smallest average error among the three techniques. The proposed method has also proved to be able to measure HR variation using CSD.
•A novel OM model is proposed for multi-unit series systems subject to random production waits.•The arrival and the duration of the production waits are both stochastic.•Maintenance Gravity Window ...(MGW) is developed to group the PM activities of the units.•MGW is suitable for the circumstance the pre-scheduled PM time for each unit is a time window.•The MGW based OM policy is more cost-effective than the other two maintenance policies.
This paper proposes an Opportunistic Maintenance (OM) scheduling model for the multi-unit serial system subject to random production waits. With the stochastic nature of production waits involved, the pre-scheduled Preventive Maintenance (PM) time for each unit changes from a specific time to a time window. To effectively group the PM activities of the units with a series of time windows, a new concept called Maintenance Gravity Window (MGW) is introduced and then a novel MGW based OM policy is developed. Whenever one of the units reaches its PM threshold or accepts a production wait to conduct PM, a PM opportunity for the system arises. At that time, all the other units, which also reach their own PM thresholds or accept this production wait, or whose gravity related to the current PM opportunity is within the MGW, will be preventively maintained together with this unit. The optimal MGW for the system is obtained by minimizing the total maintenance cost per unit time throughout the PM scheduling horizon. Finally, numerical examples and comparisons are illustrated to show the cost-effectiveness of the proposed MGW based OM policy.
Electrochromic dynamic windows for office buildings Sbar, Neil L.; Podbelski, Lou; Yang, Hong Mo ...
International journal of sustainable built environment,
06/2012, Letnik:
1, Številka:
1
Journal Article
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Odprti dostop
The next generation of advanced fenestration products includes dynamic electrochromic (EC) windows which can modulate the solar energy entering a building by application of an applied voltage. The ...windows can be switched from 62% visible transmittance (Tvis), 0.47 solar heat gain coefficient (SHGC) to a fully tinted state with ⩽2% Tvis, 0.09 SHGC. EC windows save energy in buildings – the total energy use for an eight story ASHRAE 90.1 2007 commercial office building with EC windows was modeled using the eQuest building simulation program and compared with the energy use of the same building with a variety of static glazings. The simulations were carried out in three US climate zones, encompassing a broad range of environmental exposure conditions from hot and dry (Arizona) to very cold (Minnesota). For all climate zones, building energy savings with EC glass were ⩾45% when compared to single pane static glazings common in existing building stock. When EC glass was compared to ASHRAE 90.1 2007 code compliant glazings, energy savings greater than 20% were calculated for the same building configuration. Optimum EC window control and performance strategies were derived from the modeling results. The EC glass and dimmable electric lights were synergistically controlled to maximize the use of natural daylighting and minimize electricity for lighting. Since EC glass can tint to ⩽2%, shades and/or blinds are not required for glare reduction, and building occupants always have a comfortable working environment and an unobstructed view and connection to the outdoors. All static glazing systems were assumed to have manual shading devices that are pulled by building occupants when glare becomes uncomfortable. For integrated building control systems, the peak load is significantly reduced when dynamic glazings are part of the building envelope. Consequently, chiller costs are lower, and the upfront capital costs for new building construction are reduced. Another key benefit of EC glass, elucidated by the simulations is reduction of CO2 emissions. EC glass reduces peak load carbon emissions by as much as 35% in new construction and 50% in renovation projects.
Recently, organic hybrid halide perovskites have been found to show thermochromism with good optical performance, which can be applied in smart windows to reduce building energy consumption. However, ...these perovskites have shortcomings regarding their thermochromic performance, namely long transition time, high transition temperature, and large transition hysteresis width. In this study, a hydrated MAPbI3−xClx thermochromic perovskite smart window (H‐MAPbI3−xClx TPSW) is proposed, which undergoes a reversible transition between a transparent state and a dark reddish‐brown tinted state with a high solar modulation ability of 23.7%. Most importantly, the H‐MAPbI3−xClx TPSW possesses a tunable low transition temperature of 29.4 to 51.4 °C, a controllable and narrow transition hysteresis width (7.7–13.2 °C) and a short transition time (1–4 min). Additionally, a mathematical model is developed to predict the transition temperature of the H‐MAPbI3−xClx TPSW. A field test is also conducted, demonstrating that the H‐MAPbI3−xClx TPSW fitted to a model house can reduce the indoor air temperature by 3.5 °C compared to using a quartz glass window. Overall, the H‐MAPbI3−xClx TPSW can yield excellent optical properties, while simultaneously providing remarkable transition properties, making it potentially useful for a wide range of applications in energy‐efficient buildings.
A hydrated MAPbI3−xClx thermochromic perovskite smart window is developed. The window demonstrates a passive and smart optical regulation ability between a transparent state and a tinted state. Most importantly, the window possesses a tunable low transition temperature, a controllable and narrow transition hysteresis width, and a short transition time, showing great potential for use in smart green buildings.
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