Temporal Mismatch Research Articles

Modeling fMRI BOLD signals and temporal mismatches in the cerebellar cortex

To understand brain activity relating neurons to circuits to learning and behavior, we explored a bottom-up computational reconstruction of population signals arising from cerebellum granular layer. As a first implementation, using bio-realistic computational models of cerebellum granule cell, in vivo spike train patterns were computed and then translated into functional Magnetic Resonance Imaging, Blood Oxygen-Level Dependent (BOLD) signals. The BOLD response was generated from averaged activity arising from center-surround organization modeled by using excitatory-inhibitory ratios related to experimental data. The averaged responses were converted to BOLD signals using the balloon and modified Windkessel models. Although both models generated BOLD responses corresponding to neural activity, the temporal mismatch was attributed to the response by the delayed compliance parameter in the Windkessel model. The modeling suggests that experimental variability observed in the cerebellar micro-zones could be related to compliance chances, activation patterns and number of neurons. Although detailed neuro-vasculature information was not modeled, the advantage in this methodology is that cerebellar cortex may allow seemingly linear transformations of underlying spiking that could be then used to validate network reconstructions.

Numerical study on the characteristics of hybrid seeded femtosecond optical parametric amplifier at mid-infrared wavelength

Abstract In the optical parametric amplifier (OPA) process, the phase of the pump is transmitted to the amplified signal due to the spatial walk-off effect and/or a temporal group velocity mismatch (GVM) effect between coherent light waves. As a result, the quality of amplified signal will be reduced by the phase distortion and variation of beam equality of the pump pulse. By using a pair of OPAs, the signal and idler are chosen as seeding lights in the front and back stages, respectively, so that the phase of the amplified signal can be restored, and the influence of phase distortion and beam equality deterioration of pump pulse can be eliminated. The present article also reports other characteristics of this hybrid seeded scheme, including accepted bandwidth, spectral purity, and conversion efficiency.

Downscaling Landsat-8 land surface temperature maps in diverse urban landscapes using multivariate adaptive regression splines and very high resolution auxiliary data

ABSTRACT We propose a method for spatial downscaling of Landsat 8-derived LST maps from 100(30 m) resolution down to 2–4 m with the use of the Multiple Adaptive Regression Splines (MARS) models coupled with very high resolution auxiliary data derived from hyperspectral aerial imagery and large-scale topographic maps. We applied the method to four Landsat 8 scenes, two collected in summer and two in winter, for three British towns collectively representing a variety of urban form. We used several spectral indices as well as fractional coverage of water and paved surfaces as LST predictors, and applied a novel method for the correction of temporal mismatch between spectral indices derived from aerial and satellite imagery captured at different dates, allowing for the application of the downscaling method for multiple dates without the need for repeating the aerial survey. Our results suggest that the method performed well for the summer dates, achieving RMSE of 1.40–1.83 K prior to and 0.76–1.21 K after correction for residuals. We conclude that the MARS models, by addressing the non-linear relationship of LST at coarse and fine spatial resolutions, can be successfully applied to produce high resolution LST maps suitable for studies of urban thermal environment at local scales.

The Focal Length Effect on Energy Absorption and Terahertz Generation upon Focusing Two-Color Radiation in Air

Generation of terahertz radiation upon filamentation in air of two-color radiation in loose focusing conditions with focal lengths from 30 to 312 cm and a beam diameter of 0.8 cm was studied. Two-color radiation was generated in a nonlinear BBO crystal irradiated by a converging laser beam. Measurements show that the energy input into the medium increases dramatically with a decrease in the focal length to 50 cm or less; at F = 30 cm, the energy of a terahertz pulse linearly depends on the laser pulse energy and increases significantly at F = 50 cm. Terahertz radiation is still not observed at longer focal lengths, which is apparently due to a spatio—temporal mismatch of the radiation of the first and second harmonics.

Intraspecific variation in a dominant prey species can bias marine predator dietary estimates derived from stable isotope analysis

AbstractIt is often assumed that variation in consumer stable isotope values (δ15N and δ13C) reflect shifts in diet between isotopically distinct prey species. However, an alternate hypothesis is that such variation could be as a result of spatial, temporal, or ontogenetic variation in the stable isotope values of a key prey species that propagate up marine food chains. In the Southern Ocean, Antarctic krill (Euphausia superba) occupy a key position, linking primary production to secondary consumers including fish, squid, seabirds, and marine mammals. As such Antarctic krill represent an ideal prey species to test the critical assumptions behind what has become a common method of dietary analysis in marine predators. Similar to previous studies, we found that stable isotope values of Antarctic krill exhibit significant intraspecific variation associated with both ontogenetic (size) and oceanographic factors (chlorophyll a concentration). Our modeling results showed that intraspecific variation in the stable isotope values of Antarctic krill has the potential to force mean isotope values of krill predators by as much as 2.4‰, independent of changes in the species composition of diet. Our findings indicate that intraspecific variation in the stable isotope values of a single, dominate prey species, such as Antarctic krill, has the potential to bias both absolute and relative estimates of marine predator diets using stable isotope mixing models. Therefore, caution is warranted to avoid spatial, temporal, and ontogenetic mismatches between the stable isotope values of prey sources used in mixing models and the actual stable isotope values of prey consumed by marine predators.

Late flowering time enhances insect pollination of turnip rape

Abstract Ecological intensification has been proposed as a strategy to mitigate the impacts of conventional intensive land use on pollinators and insect pollination. However, research has concentrated on the effects of land management on pollinator abundance and diversity, while studies directly measuring pollination services are still lacking for many crops and regions. This study examines the effects of landscape heterogeneity, pesticide use intensity and flowering time on insect pollination of turnip rape Brassica rapa ssp. oleifera, a major oil crop at high latitudes. The field experiment included monitoring pollinator visits on turnip rape flowers and measuring yield in 34 spring‐sown turnip rape fields in Southern Finland. The fields were situated in two landscape types that differed in the cover of arable land and represented independent gradients of pesticide use intensity and flowering time. Based on flower visits and number of seeds per silique, turnip rape was best pollinated in fields with late flowering time. The result suggests a temporal mismatch between crop flowering and the availability of pollination service in early sown fields. The increase in flower visits during summer was steeper among fields with low than high pesticide use, possibly due to a faster colony growth of important bee pollinators. Pollinator community in turnip rape fields was more diverse in heterogeneous landscapes with less arable land than in homogeneous field‐dominated landscapes, suggesting higher stability of pollination services in diverse landscapes. Total yield per plant was positively related to pesticide use intensity. The relationship between insect pollination and total yield was weakened by high compensation capacity of turnip rape, the plants producing more flowers under poor pollination. Synthesis and applications. Crop pollination can be enhanced by shifting sowing time to better match crop flowering to the peak availability of the most important pollinators. Reduced pesticide use may also enhance pollination services but can lead to the total yield reduction due to pests. This highlights the need for pollinator‐friendly pest control methods to maintain turnip rape yields while conserving pollination services.

3D Behavior Recognition Based on Multi-Modal Deep Space-Time Learning

This paper proposes a dual-stream 3D space-time convolutional neural network action recognition framework. The original depth map sequence data is set as the input in order to study the global space-time characteristics of each action category. The high correlation within the human action itself is considered in the time domain, and then the deep motion map sequence is introduced as the input to another stream of the 3D space-time convolutional network. Furthermore, the corresponding 3D skeleton sequence data is set as the third input of the whole recognition framework. Although the skeleton sequence data has the advantage of including 3D information, it is also confronted with the problems of the existence of rate change, temporal mismatch and noise. Thus, specially designed space-time features are applied to cope with these problems. The proposed methods allow the whole recognition system to fully exploit and utilize the discriminatory space-time features from different perspectives, and ultimately improve the classification accuracy of the system. Experimental results on different public 3D data sets illustrate the effectiveness of the proposed method.

Performance Characterisation and Optimisation of a Building Integrated Photovoltaic (BIPV) System in a Maritime Climate

A seasonal analysis of a long-term dataset produced by an off-grid classroom facility showcasing several solar orientated renewable technologies is presented. The performance of the building’s BIPV and battery storage system is characterised and optimisation strategies are discussed. The building experiences a typical oceanic climate defined by a relatively narrow annual temperature range and a high level of annual precipitation, resulting in significant fluctuation in PV performance throughout the year. On clear days, the battery system reaches capacity quickly and PV power output drops to the base load of the building. This curtailment of solar generation highlights the importance of developing control strategies to optimise system performance. Maximising the performance of the building requires accurate methodologies for predicting PV generation and detailed knowledge of building demand profiles. Significant correlation is observed between the solar irradiance, battery state of charge and PV power output, demonstrating the importance of these variables in any solar forecasting model. Demand profiles are deterministic and follow classroom routine. A baseline accounts for persistent systems such as the building management system that are active throughout the day, with demand peaking during occupancy. This information could be incorporated into scheduling algorithms to optimise performance. Consumption is more aligned with the solar generation profile than typical residential buildings that peak in the evening as levels of solar generation fall. The synergistic effect of buildings with different demand profiles could be a mitigation method to minimise the temporal mismatch between solar generation and consumption.

The role of seasonal thermal energy storage in increasing renewable heating shares: A techno-economic analysis for a typical residential district

European renewable energy developments have so far focussed on electricity generation, with relatively modest progress in renewable heating. Partly this is due to the temporal mismatch between solar irradiation availability and residential heating demand profiles. Seasonal thermal energy storage (STES) has been proven in several pilot projects and is market ready, albeit not currently economical. This paper sets out to assess the potential contribution of STES to increasing the renewable heating fraction in residential buildings. An existing mixed integer linear program (MILP) is extended to consider STES and applied to optimize the energy supply system for a typical residential district with efficient new-build apartment buildings, in the context of five contrasting scenarios. Achieving 100% renewable heat supply requires significant capacities of seasonal storages and is associated with substantially (14%) higher cost than in the reference scenario. To achieve a 60% renewable heat supply fraction under today's framework conditions, the cost increase compared to the reference scenario is only marginal (1%). The results in three future scenarios reflecting possible conditions in 2030 demonstrate that even higher levels of renewable heat supply could soon become economical. Overall the recommendation is to aim for renewable heat supply levels of around 60–80% combined with demand side measures such as improved insulation. Further work should focus on more systematically exploring the relationship between the grid renewable electricity fraction, available solar collector area and the optimal renewable heat integration strategy.

Waste-heat integration in smart thermal networks - A dynamic thermoeconomic approach

Abstract The transformation of large district heating networks (DHN) towards smart thermal networks is one way of contributing to a decarbonized integrated energy system. DHN might operate as a backbone receiving a variety of different energy vectors. As a smart thermal network, a DHN is therefore able to solve both spatial- and temporal mismatch of energy demand-supply, while its operation is mostly governed by fluctuating or batch-like supply of thermal exergy. Thermoeconomics is used to provide information upon third-party excess, exergetic destruction and the feasibility of waste-heat integration but currently mainly focuses on system evaluation. In this work, thermoeconomics is used to extend the information on operational level, focusing on the dynamic behavior of exergy flows in systems with various producers and consumers. The aim is to evaluate the individual contributions of energy service by the substations (the consumers on component level) to the thermoeconomic cost generation in the system. This is done through applying the principles of exergy costing to network nodes of a graph-based network model. Furthermore, product and fuel flows, which are intrinsic part of the theory of exergy cost, are defined on control volume level and on component level. A matrix formulation of the approach is developed which can be directly applied to graph-based models using the incidence matrix for topology representation. The thermoeconomic model is applied to a case study of a real existing DHN in current operation. The effect of waste-heat integration of a typical batch-like waste heat profile at 80 °C shows that the exergetic costs are dependent on the position of the network and can be quantified in economic terms, which provides important information for decentralized integration, third-party access and dynamic pricing.

Fast 3D flow reconstructions from 2D cross-plane observations

A computationally efficient flow reconstruction technique is proposed, exploiting homogeneity in a given direction, to recreate three-dimensional instantaneous turbulent velocity fields from snapshots of two dimension planar fields. This methodology, termed as ’snapshot optimisation’ or SO, can help to provide 3D data sets for studies which are currently restricted by the limitations of experimental measurement techniques. The SO method aims at optimising the error between an inlet plane with a homogeneous direction and snapshots, obtained over a sufficient period of time, on the observation plane. The observations are carried out on a plane perpendicular to the inlet plane with a shared edge normal to the homogeneity direction. The method is applicable to all flows which display a direction of homogeneity such as cylinder wake flows, channel flow, mixing layer, and jet (axisymmetric). The ability of the method is assessed with two synthetic data sets, and three experimental PIV data sets. A good reconstruction of the large-scale structures is observed for all cases. The small-scale reconstruction ability is partially limited especially for higher dimensional observation systems. POD-based SO method and averaging SO variations of the method are shown to reduce discontinuities created due to temporal mismatch in the homogenous direction providing a smooth velocity reconstruction. The volumetric reconstruction is seen to capture large-scale structures for synthetic and experimental case studies. The algorithm run time is found to be in the order of a minute providing results comparable with the reference. Such a reconstruction methodology can provide important information for data assimilation in the form of initial condition, background condition, and 3D observations.

Wind Erosion Changes in a Semi-Arid Sandy Area, Inner Mongolia, China

Wind erosion is one of the major environmental problems in drylands. Identifying the dominant natural factors of wind erosion and using targeted treatment measures are the key steps in wind erosion control. Using Horqin Left Back Banner in China as a case study, we applied the revised wind erosion equation to simulate the spatial distribution of wind erosion in the semi-arid sandy area. Contribution assessment and constraint line analysis were used to investigate the contributions of driving forces to wind erosion changes. The results showed that the wind erosion in the whole area was reduced by 0.35 t/hm2·a from 2005 to 2016. The wind factor and vegetation coverage factor had dominant contributions to the wind erosion modulus and accounted for the erosion in 49.87% and 50.13% of the total area, respectively. In addition, the average wind speed exceeding the threshold and the number of occurrences exhibited significant correlations with the wind erosion severity. Meanwhile, the mitigation effects of vegetation coverage on wind erosion decreased with the increase in wind speed. The temporal mismatch between the wind speed and vegetation coverage was the main reason for the frequent severe wind erosion in spring. Reducing the spring wind speed through adding windbreaks would be an effective method for decreasing wind erosion in semi-arid areas.

Control strategy for battery-supported photovoltaic systems aimed at peak load reduction

The use of photovoltaic (PV) technologies is one of the key means for achieving the balance between operational power demand and generation in net Zero Energy Buildings (nZEBs). However, direct use of PV power on-site is limited due to wide variability and uncertainty of PV output, the temporal mismatch between PV generation and load and other factors. Consequently, in addition to low self-consumption rates, the problem of peak grid load and peak PV feed into the grid persists. Batteries that are coupled to PV units may partially offer the solution to these problems, if operated under an intelligent control strategy. In this paper we proposed a forecast-based control strategy for battery-to-grid interaction aimed at enhancing selfconsumption and at reducing peak load. Python programming environment was used for data processing and algorithm development. Exemplification was made based on the reported hourly energy demand in one office building of 3000 m2 heated floor area located in Trondheim, Norway. Forecasting of electricity load profiles was based on the seasonal autoregressive integral moving average (SARIMA) model. For PV power forecasting, the algorithm communicated with external service – Solcast API. The search method for optimal scheduling of operational time and the extent of charging/discharging was proposed. The results showed that as opposed to conventional battery use, this control strategy allowed to achieve significantly more consistent grid interaction. It offered highly accurate battery scheduling on a day-ahead basis while utilising minimum historical data and computational resources. The algorithm may be beneficial for end-users and grid operators, and thus, it has a high potential for future integration into building energy supply systems.

Distinct neutrophil C5a receptor inflammatory events in cows initiated by chemoattractant C5a and lipopolysaccharide around parturition and in mid lactation

In neutrophils, toll-like receptor and complement component 5a (C5a) signaling are critical pathways regulating innate immunity. In cows, not much is known about the second C5a receptor, complement component 5a receptor 2 (C5AR2). It is an interesting player in sepsis treatment because it is considered to have an anti-inflammatory effect during normal inflammation. Periparturient cows are prone to severe infections, and the objectives of this study were to investigate the expression and functionality of C5AR2 during peripartum. We investigated the effect of 2 major inflammatory stimuli, C5a and lipopolysaccharide (LPS), on the expression of a selected number of genes (C5AR1, C5AR2, TLR4, ITGAM, COX2, and CXCL8) and functions linked to these receptors. Overall, TLR4, ITGAM, and C5AR2, all of which are involved in early inflammation, showed a lower expression in periparturient cows. However, an overall lower expression seems not to be the only explanation for the increased risk of sepsis in periparturient cows. Normally, in response to inflammation and as seen in the mid-lactation group, the expression of these genes increases after stimulation with LPS. However, in periparturient cows, stimulation with LPS led to a decrease in expression of these receptors, indicating a different response of neutrophils in response to LPS during this period. A decrease in ITGAM (coding for CD11b) expression complicates correct neutrophil localization and phagocytosis. Its downregulation upon stimulation might be detrimental for adequate eradication of the pathogen and might increase the risk of an imbalanced inflammation; C5AR2 seems to play a central role in this altered response. In addition, myeloperoxidase (MPO) activity in periparturient cows is lower in response to C5a stimulation. It has been suggested that MPO plays an important role in neutrophil shutdown and, thereby, timely resolution of inflammation. A decreased MPO activity might thus prolong the inflammatory reaction of the neutrophils. This finding was supported by the increased viability of the neutrophils obtained from periparturient cows. Even after stimulation, we found a lower caspase-3 activity in this group, indicating that they might be activated for a longer time compared with the neutrophils from mid-lactation cows. Accordingly, these alterations might contribute to a temporal mismatch in inflammatory responses, as often seen in severe periparturient infections.

Development of an auto-synchronization technique for improving the power stability of copper vapour laser oscillator and amplifier configuration

A technique to synchronize multiple copper vapour laser (CVL) systems in master oscillator power amplifier configuration to obtain long-duration power stability is discussed in this manuscript. The technique utilizes optoelectronic interconversion of the current pulses of CVL oscillator and amplifiers units as a feedback signal. The signal processing of the current pulses was performed using a monostable multivibrator, R–S flip-flop and passive low pass filter. The DC voltage generated corresponding to the quantum of temporal mismatch between the oscillator and the amplifier modules is sampled, averaged and compared to the set point voltage using a Programmable Logic Controller. The timing signal of the respective amplifiers could be accordingly adjusted to synchronize with the CVL oscillator optical pulses to obtain long-duration power stability.

Initial Comparison of Lithium Battery and High-Temperature Thermal-Turbine Electricity Storage for 100% Wind and Solar Electricity Supply on Prince Edward Island

Due to fundamental temporal mismatches between renewable energy generation and demand load, a long-duration energy storage system is required to power Prince Edward Island’s (PEI) electricity system exclusively from on-island wind and solar resources. While a very large lithium battery is a technically capable solution, today’s battery technology is not cost effective; even as wind and solar generation costs become increasingly competitive with fossil fuel alternatives. To explore alternative storage technologies this comparative study utilizes the established hybrid optimization model for multiple energy resources (HOMER) techno-economic modeling tool to perform an application-based high-level comparison of an efficient but costly lithium battery technology solution with a much less efficient but lower-cost thermal-storage with steam-turbine concept; both capable of enabling a 100% wind and solar powered electricity supply for the island. Interestingly, the thermal storage turbine concept is shown to be competitive, at least in principle, with projected cost reductions in lithium battery technologies while also offering a number of distinct practical advantages.

Decentralized drain water heat recovery: A probabilistic method for prediction of wastewater and heating system interaction

Temporal mismatches between heat provided by a drain water heat recovery system, and heat consumption are, although often disregarded in literature, a crucial factor in assessing the feasibility of the former. Generally, the only available information for residences is the average monthly consumption. The probabilistic method described in this paper uses observations from 113 residences to predict daily and monthly consumption profiles, using monthly consumption as a starting point. These profiles were then used to study the operation of a drain water heat recovery system, but can also be used to assess the operation of other heating methods where the supply is not controlled, such as solar thermal. The operation of the drain water heat recovery systems was predicted based on a monitoring campaign at 3 residences, measuring wastewater temperature and flow at 5-minute intervals, for over a 1-year period. The performance of this system was assessed using the performance data of 26 commercially available heat pumps, with rated power below 7 kW.The method was applied to a theoretical average Irish residence, obtained through a Monte Carlo analysis on just under 700 000 Irish residences. The method highlighted the potential for a reduction in heating related greenhouse gas emissions by 7.6% to 22%. However, this increased heating costs by 120% to 130%. At current traditional heating prices, the DWHR system for a single residence is not financially competitive with traditional systems, due to its significant capital investment. Further research should examine combining waste water streams from different residences to provide a larger flow, and potentially a high recoverable energy volume, thus improving financial viability. Policy makers should also consider incentivizing DWHR to improve its financial competitiveness and help achieve the above GHG emissions savings.

Effect of intra-urban temperature variation on tree flowering phenology, airborne pollen, and measurement error in epidemiological studies of allergenic pollen

Temperature gradients in cities can cause inter-neighborhood differences in the timing of pollen release. However, most epidemiological studies examining allergenic pollen utilize daily measurements from a single pollen monitoring station with the implicit assumption that the measured time series of airborne pollen concentrations applies across the study areas, and that the temporal mismatch between concentrations at the counting station and elsewhere in the study area is negligible. This assumption is tested by quantifying temperature using satellite imagery, observing flowering times of oak (Quercus) and mulberry (Morus) trees at multiple sites, and collecting airborne pollen. Epidemiological studies of allergenic pollen are reviewed and temperatures within their study areas are quantified. In this one-year study, peak oak flowering time was well explained by average February nighttime temperature (R2 = 0.94), which varied by 6 °C across Detroit. This relationship was used to predict flowering phenology across the study region. Peak flowering ranged from April 20–May 13 and predicted a substantial portion of relative airborne oak pollen concentrations in Detroit (R2 = 0.46) and at the regional pollen monitoring station (R2 = 0.61). The regional pollen monitoring station was located in a cooler outlying area where peak flowering occurred around May 12 and peak pollen concentrations were measured on May 15. This provides evidence that the timing of pollen release varies substantially within a metropolitan area and challenges the assumption that pollen measurements at a single location are representative of an entire city. Across the epidemiological studies, 50% of study areas were not within 1 °C (equal to a lag or lead of 4 days in flowering time) of temperatures at the pollen measurement location. Epidemiological studies using a single pollen station as a proxy for pollen concentrations are prone to significant measurement error if the study area is climatically variable.

Identification and interpretation of spatial–temporal mismatch between taxi demand and supply using global positioning system data

Taxis provide a type of on-demand mobility service in urban transportation. There are growing concerns regarding the level of service of taxis in satisfying residents’ mobility demand. However, the mismatch between demand and supply of taxi services has not been resolved even with the introduction of app-based vehicle services. In this study, three indicators are constructed using the Shanghai taxi global positioning system (GPS) dataset to reveal the spatial–temporal mismatch pattern. The issue is further analyzed via a case study, in which seven regions with frequent mismatch patterns are identified in the time period from 21:00 to 22:00. Then, a multinomial logistic regression model is employed to identify the demographic and built-environment factors contributing to the taxi mismatch problem. The study results show that population density, residential areas, the number of points of interest, and road density have significant relationships with the taxi undersupply. In contrast, the areas of commercial lands, as well as the other two transportation-related factors, that is, the number of bus stops and the distance to nearest subway station, are observed to be statistically significant for both “oversupply” and “undersupply” conditions. This study provides valuable insights for identifying mismatch patterns and interpreting the mismatch problem as a function of spatially explicit factors that are of great use for urban governance, especially in the improvement of taxi efficiency, taxi management, and urban planning.

Estimation of the numerical modeling accuracy of the Black Sea thermohaline fields based on using ARGO profiling floats

The paper considers the matters of numerical modeling estimation accuracy of temperature and salinity three-dimensional fields in the monitoring and forecasting center of the Black Sea. Automatic system of analysis and forecast of the Black Sea state is run in the center in an operational mode. The data of in situ measurements from ARGO profiling floats regularly provided by the European Marine Forecasting Service – Copernicus – were used to solve the problem. Spatial and temporal mismatch between the model data and in situ measurements was eliminated to form a joint sample of these two data sources. Comparison is performed for the time period from 2012 to 2015. The results show quite good simulation accuracy of the ther-mohaline fields, however, the problems of modeling the temperature fields in the 5-30 m layer were detected where there is a fairly narrow seasonal thermocline in late spring, summer and early autumn.