Equivalent Air Research Articles

Evaluation of Thermal Indices as the Indicators of Heat Stress in Dairy Cows in a Temperate Climate.

Simple SummaryWhen the ambient temperature exceeds the upper limit of a certain temperature range, heat stress is triggered and then negatively affects the production, reproduction, health, and welfare of livestock animals. Due to the limitations of ambient temperature alone as a representative measure of the thermal environment, heat stress is commonly assessed by thermal indices, which contain two or more environmental parameters representing the influence of heat exchanges between the animal and its environment. To understand and utilize the thermal indices better, we evaluated several thermal indices commonly used in the heat stress assessment of dairy cows. We found that the comprehensive climate index (CCI), which includes air temperature, relative humidity, wind speed, and solar radiation, showed a better relationship with the animal-based indicators (i.e., rectal temperature, skin temperature, and eye temperature) of heat stress. According to the results of this study, the CCI has the potential to replace the temperature–humidity index in quantifying the severity of heat stress in dairy cows.Many thermal indices (TIs) have been developed to quantify the severity of heat stress in dairy cows. Systematic evaluation of the representative TIs is still lacking, which may cause potential misapplication. The objectives of this study were to evaluate the theoretical and actual performance of the TIs in a temperate climate. The data were collected in freestall barns at a commercial dairy farm. The heat transfer characteristics of the TIs were examined by equivalent air temperature change (ΔTeq). One-way ANOVA and correlation were used to test the relationships between the TIs and the animal-based indicators (i.e., rectal temperature (RT), respiration rate (RR), skin temperature (ST), and eye temperature (ET)). Results showed that the warming effect of the increased relative humidity and the chilling effect of the increased wind speed was the most reflected by the equivalent temperature index (ETI) and the comprehensive climate index (CCI), respectively. Only the equivalent temperature index for cows (ETIC) reflected that warming effect of solar radiation could obviously increase with increasing Ta. The THI and ETIC showed expected relationships with the RT and RR, whereas the CCI and ETIC showed expected relationships with the ST and ET. Moreover, CCI showed a higher correlation with RT (r = 0.672, p < 0.01), ST(r = 0.845, p < 0.01), and ET (r = 0.617, p < 0.01) than other TIs (p < 0.0001). ETIC showed the highest correlation with RR (r = 0.850, p < 0.01). These findings demonstrated that the CCI could be the most promising thermal index to assess heat stress for housed dairy cows. Future research is still needed to develop new TIs tp precisely assess the microclimates in cow buildings.

NBS Impact Evaluation with GREENPASS Methodology Shown by the Case Study ‘Fischbeker Höfe’ in Hamburg/Germany

The implementation of nature-based solutions (NBS) in urban regeneration aims to improve citizens’ health and well-being. Therefore, tools need to be applied to identify the most suitable and efficient location and type of NBS. Within the CLEVER-cities H2020 project, the Greenpass method has been chosen to evaluate different design solutions regarding thermal comfort and physiological equivalent temperature (PET), energy, water and air fluxes. The Greenpass system comprises of standardized tools, reports and a unique set of Key Performance Score (KPS) and Key Performance Indicators (KPI). This paper deals with the impact assessment of NBS by the use of the innovative Greenpass system for the CLEVER-cities project ‘Fischbeker Höfe’ in Hamburg, Germany to ensure human health and well-being improvements for the citizens. To that end and considering the climate change context, thermal comfort is a KPI with high relevance in terms of the NBS co-benefits. Based on the PET within a project area Greenpass calculates the Thermal Comfort Score (TCS). The share of the different PET classes within the project area is multiplied with a weighting factor and summarized to the TCS. The results of the climate resilience analysis of the urban development area ‘Fischbeker Höfe’ in Hamburg are presented and discussed in comparison to a conventional architecture that disregards NBS, showing improvement with regards to four out of five KPS. Based on the evaluation results, advice is given to the co-creative design team on how to further improve the design towards climate resilience. The Greenpass system has proven to be a powerful and tailored tool to support climate resilient urban design and architecture. It provides a standardized and comprehensible but still scientific basis for decisions in a highly efficient and understandable way.

Development and validation of a model for assessing neutron fluence with lithium fluoride thermoluminescent detectors

Lithium fluoride thermoluminescent detectors are commonly used for neutrons measurements. However, the calibration is usually performed with readily available gamma sources in terms of gamma equivalent air kerma instead of the more meaningful neutron fluence. Neutron calibration coefficients in terms of neutron fluence depend strongly on the experimental conditions and can thus usually not be found in literature. Therefore, the goal of this work was to develop and validate a model to calculate such neutron calibration coefficients and to use this model to quantify the main sources of uncertainty. Comparison of the neutron calibration coefficients predicted by the model with experimental data from literature and this work showed reasonable agreement. However, a slight systematic deviation was found, probably caused by the significant uncertainty on the relative luminescence efficiency values predicted by the recently developed Microdosimetric d(z) Model for the low energy charged particles released during the 6Li(n,α)3H reaction. Therefore, it was decided to use relative luminescence efficiency values based on the experimental results instead. The model also identified the neutron energy and angular distribution and the luminescence reader light collection geometry as the main sources of uncertainty. Imprecise knowledge of these experimental input parameters can easily lead to uncertainties of the order of tens of percent on the calculated neutron calibration coefficients. The developed model is applicable for neutron energies below 0.01 MeV, but could be extended to higher energies in the future.

Measurement of thermal boundary resistance between water and superhydrophobic surfaces by the bi-directional differential 3ω method

This study describes a new approach for measuring thermal boundary resistance between water and superhydrophobic surfaces with a thin air layer in between. This new bi-directional differential 3ω method was used to detect the small thermal boundary resistance due to superhydrophobicity. The superhydrophobic surface was prepared by spin-coating a commercial colloidal solution (Glaco Mirror Coat Zero) on the borosilicate glass substrate with a thin film-heater line for the 3ω measurements. The surface wettability was changed from superhydrophobic to superhydrophilic by plasma treatment of the coating surface to obtain the reference state without the air layer (thermal boundary resistance), required for the differential measurement. The obtained thermal boundary resistance was 7.5 × 10−6 [(K･m2)/W], and its equivalent air layer thickness was 0.2 μm and was consistent with the surface topology observed using an atomic force microscope. This measurement technique is considered useful for characterizing the thermal resistance of superhydrophobic structures used in heat transfer applications, such as phase-change heat transfer surfaces and microchannel heat exchangers.

Co-existing “spear-and-shield” air filter: Anchoring proteinaceous pathogen and self-sterilized nanocoating for combating viral pandemic

Infectious pollutants bioaerosols can threaten human public health. In particular, the indoor environment provides a unique exposure situation to induce infection through airborne transmission like SARS-CoV-2. To prevent the infection from spreading, personal protective equipment or indoor air purification is necessary. However, it has been discovered that the conventional filter can become contaminated by pathogen-containing aerosols, meaning that advanced filtering and self-sterilization systems are required. Here, we fabricate a multilayered nanocoating around the fabric using laponite (LAP) with Cu2+ ions (LAP-Cu2+ nanocoating) two contradictory functions in one system: trapping proteinaceous pathogens and antibacterial effect. Due to the strong LAP-protein interaction, albumin and spike protein (S-protein) are trapped into the fabric when proteins are sprayed using a nebulizer. The protein-blocking performance of the nanocoated fabric is 9.55-fold higher than bare fabric. These trapping capacities are retained after rinsing and repeated adsorption cycles, showing reproducibility for air filtration. Even though the protein-binding occurred, the LAP-Cu2+ fabric indicates antibacterial effect. LAP-Cu2+ fabric has an equivalent air and water transmittance rate to that of bare fabric with a stability under physiological environment. Therefore, given its excellent “Spear-and-shield” functions, the proposed LAP-Cu2+ fabric shows great potential for use in filter and masks during the viral pandemic.

Mathematical Modeling and Experimentation of Airflow Disturbance in Tramcar-roadway System

This paper analyzes the variation law of equivalent air resistance in a mine car-roadway system, establishes the index system of influencing factors of airflow disturbance. Using experimental system of mine ventilation simulation, the characteristics of air supply of the roadway, blocking coefficient and disturbance of air resistance in roadway are studied. Furthermore, the mathematical model for calculating the equivalent disturbance air resistance is built in the different tramcar positions. The result shows that the tramcar-roadway system has a positive disturbance effect when the tramcar’s speed is greater than the air velocity of the roadway, and it is equivalent to air regulation by addition of pressure of the mine ventilation system. The negative disturbance effect is equivalent to air regulation by addition of resistance. It has the stronger disturbance effect if the air velocity or the roadway section is small. The maximum disturbance variation of air resistance occurs at the moment while the tramcar mine car enters or leaves the roadway. The error between the mathematical model and the measured data is 8.12 %. The research results can provide theoretical basis for intelligent regulation of mine ventilation system.

A regression-based three-phase approach to assess outdoor thermal comfort in informal micro-entrepreneurial settings in tropical Mumbai.

Urban heat poses a public health risk to the residents of megacities in developing countries because the population spends a significant amount of time outdoors to work and socialize with limited cooling resources. Understanding the drivers of outdoor comfort and heat stress in informal work settings is important to design climate-sensitive outdoor spaces and reduce heat vulnerability. We present outdoor thermal comfort perceptions (OTCPs) of people engaged in outdoor micro entrepreneurial activities in Mumbai using seasonal surveys and biometeorological observations. We propose a three-phase approach to analyze the relative importance of climatic and non-climatic variables for OTCPs. The first phase evaluates the seasonal and intra-neighborhood variation of thermal sensation votes (TSV) with respect to physiological equivalent temperature (PET) and air temperature. Second, we include physiological parameters to evaluate the seasonal and intra-neighborhood variation of overall sensation votes (OSV). Third, we consider aggregated survey responses and include behavioral and perceptual variables to determine their relative significance. We employ three linear modeling techniques to assess model performance in explaining the variability of OTCP using OSV as dependent variable. Results reveal that microclimatic parameters alone are unable to explain the variability of OTCP. Our results yield a neutral PET value (PETneutral) of 23.75 °C for Mumbai in the winter. PETneutral was higher for activities at the clothing market compared to other micro entrepreneurial activities. Acclimatization significantly improved comfort in the summer, while evaporative cooling was beneficial in the winter. Further, an ANCOVA and ordinal logistic regressions demonstrate the importance of behavioral attributes (presence in the location, expectation, beverage intake) in explaining the variance in OTCP. Our study also reveals that wind speed and humidity play an important role in shaping overall comfort in the Mumbai neighborhoods.

Decomposition analysis of air pollutants during the transition and post-transition periods in the Czech Republic

In index decomposition analysis, it is common to decompose changes in energy-related CO2 emissions to give the effects of five contributing factors. However, it is extremely challenging to derive the equivalent air pollutant emission coefficient by fuel type for air pollutants. As a result, air pollutant emissions have typically been decomposed into three factors, i.e. the scale, structure, and emission intensity factors. Using a unique facility-level dataset for the Czech Republic, we decompose air pollutant emissions into five factors, i.e. by decomposing the emission intensity effect further into the fuel-intensity, fuel-mix, and emission-fuel intensity factors. We use the Logarithmic Mean Divisia Index method to decompose annual changes in the emissions of four types of air quality pollutants stemming from large stationary emission sources. Our analysis covers the period 1990–2019, during which the Czech economy transited from a centrally-planned to a market economy and implemented strict environmental regulation to become a full member of the European Union. The emissions decreased substantially in the 1990s, remained then at stable levels, and declined again thereafter. Effects contributed to the changes are quantified. We also study how the results differ if one relies on the standard 3-factor decomposition and on a 4-factor analysis.

Combined Effects of Midlevel Dry Air and Vertical Wind Shear on Tropical Cyclone Development. Part II: Radial Ventilation

AbstractThis study demonstrates how midlevel dry air and vertical wind shear (VWS) can modulate tropical cyclone (TC) development via radial ventilation. A suite of experiments was conducted with different combinations of initial midlevel moisture and VWS environments. Two radial ventilation structures are documented. The first structure is positioned in a similar region as rainband activity and downdraft ventilation (documented in Part I) between heights of 0 and 3 km. Parcels associated with this first structure transport low–equivalent potential temperature air inward and downward left of shear and upshear to suppress convection. The second structure is associated with the vertical tilt of the vortex and storm-relative flow between heights of 5 and 9 km. Parcels associated with this second structure transport low–relative humidity air inward upshear and right of shear to suppress convection. Altogether, the modulating effects of radial ventilation on TC development are the inward transport of low–equivalent potential temperature air, as well as low-level radial outflow upshear, which aid in reducing the areal extent of strong upward motions, thereby reducing the vertical mass flux in the inner core, and stunting TC development.

Lightning mechanical damage prediction in carbon/epoxy laminates using equivalent air blast overpressure

We propose a new, alternative approach to predict lightning mechanical damage in AS4/3506 carbon/epoxy laminates using equivalent air blast overpressure (ABO). Three lightning mechanical damage models are presented: i) the Shock Wave Overpressure (SWO) model, ii) the Conventional Weapons Effects Program (CONWEP) ABO model, and iii) the Coupled Eulerian-Lagrangian (CEL) ABO model. SWOs were determined from classical shock wave theory and the arc channel energy balance equation, and directly applied within pre-described arc channel areas. ABOs in the CONWEP and CEL models were calculated for equivalent TNT explosions and applied over the entire laminate surface. In contrast to the SWO and CONWEP models, the CEL model simulated the coupled fluid-structure interactions of the blast waves with the composite structures. Although the fundamental physics was different, both SWO and ABO induced similar dynamic structural responses and damage behavior within AS4/3506 carbon/epoxy laminates. The fiber and matrix failure, predicted using Hashin's four failure criteria, was not imminent at any of these peak currents. This implies that purely mechanical in-plane damage is unlikely to occur and thus is not a major concern for lightning strikes. This study shows that the ABO models can be used to predict lightning mechanical damage in composite structures as an alternative to a complex SWO model.

A new methodology to establish the relationship between equivalent shot velocity and air pressure by surface roughness for shot peening

The study of shot peening process by numerical simulation is becoming mature and efficient. Shot velocity is very important, which is related to the accuracy of simulation results. However, the actual shot peening process was directly controlled by air pressure and other parameters, instead of shot velocity. This paper details a new method to obtain the equivalent shot velocity as initial velocity used in simulation corresponding to air pressure in the actual shot peening. Firstly, under the same shot peening parameters, the linear relationship between the roughness and air pressure, and the linear relationship between the roughness and equivalent shot velocity were obtained by experiment and simulation, respectively. Secondly, the relationship between equivalent shot velocity and air pressure is established by the intermediate surface roughness. At last, the validity and reliability of the relationship be verified by arc height, residual stresses, coverage, and existing literature. In addition, this paper introduces a new method to calculate the number of shots used in combined discrete element model (DEM) and finite element model (FEM), taking into account the mass flow, nozzle movement speed and nozzle-workpiece distance, and other parameters. In this way, it is of significance to characterize the shot peening equipment rapidly and obtain the equivalent shot velocity used in the simulation to optimize the shot peening parameters in the aerospace and automotive industry.

Accuracy Evaluation of EPL and ETAR Algorithms in the Treatment Planning Systems using CIRS Thorax Phantom.

Background: It is recommended for each set of radiation data and algorithm that subtle deliberation is done regarding dose calculation accuracy. Knowing the errors in dose calculation for each treatment plan will result in an accurate estimate of the actual dose achieved by the tumor.Objective: This study aims to evaluate the equivalent path length (EPL) and equivalent tissue air ratio (ETAR) algorithms in radiation dose calculation.Material and Methods: In this experimental study, the TEC-DOC 1583 guideline was used. Measurements and calculations were obtained for each algorithm at specific points in thorax CIRS phantom for 6 and 18 MVs and results were compared.Results: In the EPL, calculations were in agreement with measurements for 27 points and differences between them ranged from 0.1% to 10.4% at 6 MV. The calculations were in agreement with measurements for 21 points and differences between them ranged from 0.4% to 13% at 18 MV. In ETAR, calculations were also in consistent with measurements for 21 points, and differences between them ranged from 0.1% to 9% at 6 MV. Moreover, for 18 MV, the calculations were in agreement with measurements for 17 points and differences between them ranged from 0% to 11%. Conclusion: For the EPL algorithm, more dose points were in consistent with acceptance criteria. The errors in the ETAR were 1% to 2% less than the EPL. The greatest calculation error occurs in low-density lung tissue with inhomogeneities or in high-density bone. Errors were larger in shallow depths. The error in higher energy was more than low energy beam.

Aerosol dynamics modeling of sub-500 nm particles during the HOMEChem study.

We spend most of our time in built environments. The cumulative exposure to particulate matter (PM) occurring in these built environments can potentially be comparable to or even exceed that occurring outdoors. Therefore, it is critical to understand the sources, dynamics, and fate of PM in built environments. This work focuses on aerosol dynamics modeling (including coagulation, deposition, and exfiltration) of sub-500 nm particles measured inside a test house during the HOMEChem campaign while performing prescribed cooking activities. Deposition characteristics of the test house, emission rates and factors, and the fate of particles are presented. Number emission rates calculated for two different heat sources (stove and hot plate) and the various meals cooked on them were highest for sub-10 nm particles. Coagulation and deposition contributed comparably to the particle number concentration decay. Most of the PM (90% number-based and 70% mass-based) deposited within the house while the remaining fraction left the test house volume via exfiltration. Simulation results show that while increased air exchange rate reduces indoor PM mass concentration, it can lead to increased number concentration. An increase from 0.5 to 5 ACH (comparable to the equivalent air change rate from running a well-dimensioned portable air cleaner) would result in a 70% reduction in PM mass-based exposure while a further increase from 5 to 20 ACH would only result in an additional 21% reduction.

Influence of the Water Vapour Permeability of Airtight Sheets on the Behaviour of Facade

The air-tightness of the thermal envelope of buildings is one of the measures to reduce their energy demands in order to achieve global warming reduction targets. To this end, airtight sheets with different water vapour permeability characteristics are used. The different products studied are highly dispersed in terms of equivalent air thickness values, leading to confusion. After the analysis carried out, it is concluded that all airtight sheets are vapour barriers. To clarify whether or not these sheets are necessary as vapour barriers, a condensation analysis was carried out on 13 different facades for 3 climate zones with severe winters as defined in Spanish regulations. The results reveal that interstitial condensation occurs in only 7 of the 39 case studies, with the traditional facades of brickwork with render causing the greatest problems if the appropriate products are not used. In these cases, airtight sheets with water vapour barrier characteristics must be applied on the interior face of the insulating material. In all other cases (32), the airtight sheets must be permeable to water vapour if it is looked for a more breathable wall to water vapour and a better control of the interior humidity conditions.

Upper-room ultraviolet air disinfection might help to reduce COVID-19 transmission in buildings: a feasibility study.

As the world’s economies come out of the lockdown imposed by the COVID-19 pandemic, there is an urgent need for technologies to mitigate COVID-19 transmission in confined spaces such as buildings. This feasibility study looks at one such technology, upper-room ultraviolet (UV) air disinfection, that can be safely used while humans are present in the room space, and which has already proven its efficacy as an intervention to inhibit the transmission of airborne diseases such as measles and tuberculosis. Using published data from various sources, it is shown that the SARS-CoV-2 virus, the causative agent of COVID-19, is highly likely to be susceptible to UV-C damage when suspended in air, with a UV susceptibility constant likely to be in the region 0.377–0.590 m2/J, similar to that for other aerosolised coronaviruses. As such, the UV-C flux required to disinfect the virus is expected to be acceptable and safe for upper-room applications. Through analysis of expected and worst-case scenarios, the efficacy of the upper-room UV-C approach for reducing COVID-19 transmission in confined spaces (with moderate but sufficient ceiling height) is demonstrated. Furthermore, it is shown that with SARS-CoV-2, it should be possible to achieve high equivalent air change rates using upper-room UV air disinfection, suggesting that the technology might be particularly applicable to poorly ventilated spaces.

A not‐so‐green choice? The high carbon footprint of long‐distance passenger rail travel in Canada

It is commonly assumed that taking the train serves as a more climate‐friendly means of travel than flying by commercial aircraft. Nevertheless, in Canada, long‐distance rail services are powered by aging and inefficient diesel locomotives. Moreover, long‐haul passenger trains are not typically loaded to capacity, and they must travel longer distances than equivalent air routes (which are able to benefit from more direct flight paths). This viewpoint considers whether traveling long‐distance by train generates a larger climatic footprint than flying by commercial aircraft, and offers a basic carbon footprint analysis and modal comparison of three long‐distance routes in Canada. It finds that taking the train does indeed generate a larger climatic impact than flying, in the cases of VIA Rail's trips between Toronto and Vancouver and between Montreal and Halifax, even when taking air travel's additional non‐CO 2 warming impact into account. While travelling by train within the modernized Quebec City‐Windsor Corridor generates a smaller climatic footprint than flying, VIA Rail's greenhouse gas emissions factor within the Corridor is still far higher than international rail comparisons. The viewpoint concludes by enumerating some policy changes which could reverse this dynamic and help Canadian long‐distance rail fulfill its reputation as a green choice.

Lobsters with pre-existing damage to their mechanosensory statocyst organs do not incur further damage from exposure to seismic air gun signals

Staotcysts, the mechanosensory organs common to many marine invertebrates, have shown sensitivity to aquatic noise. Previously, rock lobsters (Jasus edwardsii) from a remote site with little exposure to anthropogenic noise incurred persistent damage to the statocyst and righting reflex following exposure to seismic air gun signals. Here, J. edwardsii collected from a site subject to high levels of anthropogenic noise were exposed to an equivalent seismic air gun signal regime as the previous study of noise-naïve lobsters. Following exposure, both control and exposed treatments were found to have damage to the statocyst equivalent to that of noise-naïve lobsters following seismic exposure, which led to the conclusion that the damage was pre-existing and not exacerbated by seismic exposure. The source of the damage in the lobsters in this study could not be ascertained, but the soundscape comparisons of the collection sites showed that the noisy site had a 5–10 dB greater level of noise, equivalent to a 3–10 times greater intensity, in the 10–700 Hz range than was found at the remote collection site. In addition to the lack of further damage following seismic exposure, no disruption to the righting reflex was observed. Indeed, compared to the noise naïve lobsters, the lobsters here demonstrated an ability to cope with or adapt to the mechanosensory damage, indicating a need for better understanding of the ecological impacts of the damage caused by low frequency noise on marine organisms. More broadly, this study raises historical exposure to noise as a previously unrecognised but vitally important consideration for studies of aquatic noise.

Improvement of acoustic model and structural optimization design of porous asphalt concrete based on meso-structure research

In order to further reveal the influence of voids on sound absorption performance of porous asphalt pavement, more factors were considered to improve an acoustic model (Zwikiker-Kosten) and structural optimization design of porous asphalt concrete (PAC) based on meso-structure was conducted in this paper. Based on the Otsu algorithm, a square image segmentation algorithm was proposed through comparative analysis to obtain the meso-structure characteristic parameters of voids in porous asphalt concrete. Combined with the effect of airflow velocity on the flow resistance and the measured sound absorption spectrum, the relationship between void length and pavement thickness was quantified, and the Zwikiker-Kosten model of rigid skeleton porous material was improved and verified for the prediction of sound absorption performance of PAC. Besides, the influence of void parameters on the sound absorption performance of PAC was analyzed, the structural optimization design was carried out for the road dominated by small vehicles, and proposing pavement design parameters at last. The results show that the two-dimensional air voids obtained by square region segmentation algorithm have high accuracy, which can be used for the recognition and segmentation of voids in CT images; According to the comparative and correlation analysis, the improved Zwikiker-Kosten model can accurately predict the sound absorption performance of PAC; The peak sound absorption coefficient (SAC) of PAC is mainly affected by air voids, while its corresponding frequency is mainly affected by the length of voids. Moreover, the road dominated by small vehicles was recommended to adopt the following design parameters: void equivalent diameter, air void and pavement thickness should be limited to about 3 mm, 18% and 30 mm, respectively.

An equivalent temperature drop method for evaluating the operating performances of ASHP units jointly affected by ambient air temperature and relative humidity

It has been known that the actual operating performances of a space heating ASHP unit are significantly impacted by the joint effect of ambient air temperature, Ta, and relative humidity, RH. To enable a convenient evaluation of the operating performances of a space heating ASHP unit with a reasonable accuracy, an equivalent temperature drop (ETD) method has been developed. The ETD method transferred the impacts of frosting-defrosting on the operating performances of ASHP units into that of an equivalent ambient air temperature drop, so that the joint effects of Ta and RH on the actual operating performances of the ASHP units may be assessed using a single parameter of equivalent ambient air temperature. In this paper, the models for predicting the output heating capacity of an ASHP unit operated at both frosting and non-frosting conditions were firstly established through either regression analysis or referring to previous related studies. Secondly, with the availability of the models, the ETD method was developed for evaluating the actual operating performances of ASHP units at different ambient conditions. Thirdly, the developed ETD method was verified by a field study on the operating performances from an ASHP unit installed in Beijing. The field study results demonstrated that for any frosting operating conditions, using the ETD method, a corresponding non-frosting condition at which the field ASHP would output the same heating capacity may be identified. Furthermore, the use of ETD method can also distinguish the individual impacts from either Ta or RH on the actual operating performances of an ASHP unit.

Leakiness and flow capture ratio of insect pectinate antennae.

The assumption that insect pectinate antennae, which are multi-scale organs spanning over four orders of magnitude in size among their different elements, are efficient at capturing sexual pheromones is commonly made but rarely thoroughly tested. Leakiness, i.e. the proportion of air that flows within the antenna and not around it, is a key parameter which depends on both the macro- and the microstructure of the antenna as well as on the flow velocity. The effectiveness of a structure to capture flow and hence molecules is a trade-off between promoting large leakiness in order to have a large portion of the flow going through it and a large effective surface area to capture as much from the flow as possible, therefore leading to reduced leakiness. The aim of this work is to measure leakiness in 3D-printed structures representing the higher order structure of an antenna, i.e. the flagellum and the rami, with varying densities of rami and under different flow conditions. The male antennae of the moth Samia cynthia (Lepidoptera: Saturniidae) were used as templates. Particle image velocimetry in water and oil using 3D-printed scaled-up surrogates enabled us to measure leakiness over a wide range of equivalent air velocities, from 0.01 m s-1 to 5 m s-1, corresponding to those experienced by the moth. We observed the presence of a separated vortex ring behind our surrogate structures at some velocities. Variations in the densities of rami enabled us to explore the role of the effective surface area, which we assume to permit equivalent changes in the number of sensilla that host the chemical sensors. Leakiness increased with flow velocity in a sigmoidal fashion and decreased with rami density. The flow capture ratio, i.e. the leakiness multiplied by the effective surface area divided by the total surface area, embodies the above trade-off. For each velocity, a specific structure leads to a maximum flow capture ratio. There is thus not a single pectinate architecture which is optimal at all flow velocities. By contrast, the natural design seems to be robustly functioning for the velocity range likely to be encountered in nature.