Search results

In this paper, a light-weight, low-power atmospheric multi-parameter sensor (AMPS), which could be mounted on small flying platforms such as a tethered balloon, a quad-rotor unmanned aerial vehicle (UAV), a UAV helicopter, etc., is implemented and integrated to sample vertical distribution of aerosols with integrated parameters of aerosol particle concentration, temperature, relative humidity and atmospheric pressure.

The AMPS integrates three kinds of probes in an embedded system. A synchronous method based on GPS is proposed to drive the laser aerosol particle sensor, the temperature and humidity probe and the pressure probe to sample four channels approximately simultaneously. Different kinds of housing are designed to accommodate various flying platforms, and the weight is controlled to adapt the payload of each platform.

A series of validation tests show that while the AMPS achieves high precision, its power consumption is less than 1.3 W, which is essential for light flying platforms. The AMPS was mounted on different flying platforms and the difference was evaluated. For three times every five days, vertical profiles of PM2.5 and PM10 concentrations were observed by the AMPS mounted on a quad-rotor UAV, which revealed the significant correlation between the aerosol particle concentration and atmospheric parameters.

A new light-weight and low-power AMPS for small flying platforms is designed and tested, which provides an effective way to explore the properties of aerosol vertical distribution, and to monitor pollutants flexibly.

The electrohydrodynamic (EHD) dispersion of atmospheric aerosols consisting of a couple stress fluid through a vertical channel, when the walls are held at different temperatures is studied by using Taylor dispersion model. Analytical solutions for the nonlinear coupled equations are obtained using a regular perturbation technique (RPT) with buoyancy number, N(<<1) as the perturbation parameter. The effect of electric field and couple stress parameter on velocity, temperature and dispersion of aerosols are numerically computed and the results are represented graphically.

Describes the development and application of an aerosol model for regional air quality simulations. The aerosol model MADE is based on a modal concept and describes the chemical composition and the size distribution of atmospheric particulate matter. Primary as well as secondary aerosol components are considered in the model, which is fully integrated into the photochemical transport model EURAD. The model system has been applied to a European domain with different resolutions, using a one‐way nesting procedure. Simulations show the potential importance of secondary organics of anthropogenic and biogenic origin for the tropospheric particle loading. In addition it is shown that a reduction in precursor emissions for the inorganic ion fraction of PM (sulphate, nitrate and ammonium) does not necessarily lead to an equivalent reduction in PM2.5 mass concentrations, as for example a reduction in sulphate aerosol caused by reduced SO₂ emissions might be compensated by enhanced formation of nitrate aerosols in certain regions.

We present the equations for condensation in cooled upward laminar flow in tubes and consider their solution for low vapour concentrations and variable vapour‐gas thermodynamic properties. We treated the full problem, including coupling with the aerosol size distribution, by using the PSI‐CELL (Particle Source in Cell) method. The particle trajectories start from the point where the particles are generated homogeneous nucleation. Particle size distribution and vapour scavenging by particles are obtained in forced convection and mixed convection regions. Calculations were also conducted with respect to tube diameters.

Discusses computational challenges in air quality modelling (as viewed by the authors). The focus of the paper will be on Di, the “current” state‐of‐affairs. Owing to limitation of space the discussion will focus on only a few aspects of air quality modelling: i.e. chemical integration, sensitivity analysis and computational framework, with particular emphasis on aerosol issues.

The success of vapour phase soldering for electronic assemblies has led to the availability of several heat transfer fluids for the purpose. This paper aims to demonstrate the significance of the differing properties of fluids, illustrated by measurements on the three most commonly used in the UK. These three, as well as any future fluids, can be judged in terms of (i) vapour temperature and its influence on soldering yields and materials properties; (ii) stability of soldering temperature with time; (iii) heat transfer efficiency; (iv) power requirements and thermal control; (v) rosin solubility and flux wash‐off; (vi) toxicity, especially under thermal stress; (vii) corrosivity and its dependence on process control; and (viii) consumption of fluid.

Among others, the resuspension of fine and ultrafine particulate matters (PMs) on air due by land take effect is an uncovered issue. The relation between land use change and fluxes of PM is not systematically observed even if the common classification of ecosystem services (ESs) clearly shows relationship between soil and aerosol concentrations. Soil does not act only as carbon pool, but it is also a crucial variable for the resuspension dynamic of particulates. If key policies of sustainable urban development is focused on “quality of life,” it is necessary to map and evaluate the effect of land take on airborne fluxes in metropolitan areas. The paper aims to discuss these issues.

The paper allows to introduce pioneer studies on air quality in large urban areas outling a methodology of particulate field measurement. It introduces newer quantitative/qualitative assessment of environmental effect due to urbanization ensuring a major efficiency on ES degradation.

Expected results are the estimation of resuspension dynamics of aerosol for typical land cover pattern.

Implications are mainly destinated to increase significant knowledge and general awareness of the environmental effect caused by urban growth: urban areas act as a hotspot for health risk as both particle sources and human population are concentrated in these areas.

Considering that cardiovascular diseases are significantly caused by air quality, the paper aims to support sustainable planning policies aimed to achieve a better quality of environment on urban areas.

The aim of the paper is to present the results of investigations of fine particle generation by small biomass combustion and the possibility of reducing the emissions by electrostatic precipitation.

The grains, wood‐logs, wood‐, mixed‐ and straw‐pellets were combusted in two stoves and two boilers. The set‐ups were operated according to DIN‐4702. Particle number concentration in the gas flow was measured by Scanning Mobility Particle Sizer and particle mass concentration was measured according to the Guidelines VDI‐2066 upstream and downstream a novel space charge electrostatic precipitator (ESP). The ESP consists of an ioniser and a grounded brush inside of a tube form grounded collector electrode.

The ESP ensures stable operation at gas temperatures up to 350°C. The use of sharp‐points high voltage electrode ensures effective particle charging at high particle number concentrations. The combustion of wood‐pellets is characterized by lower particle mass concentrations. The highest particle mass concentrations were observed by the straw‐pellets combustion. The ESP ensures particle collection with mass collection efficiency 87±3% for wood‐logs and 82±2% for wood‐pellets combustion.

The novel ESP is recommended for exhaust gas cleaning from small scale biomass combustion facilities and domestic heating units. The use of the ESP would reduce the emissions of fine aerosol into the atmosphere and improve the air quality.

The paper presents the comparative analysis of particle size distribution and particle mass concentrations in the exhaust gas from small‐scale combustion units for different types of biomass. The study confirms the possibility to reduce particle emissions by electrostatic precipitation. The originality of the technology and apparatus is patently protected.

Daylight plays a crucial role in the attainment of building energy savings. Harnessing daylight in building designs will require the need for daylight illuminance data. However, daylight illuminance data are scarce due to few measuring stations. Aside from being sparse, illuminance measuring stations can be expensive to set up, thus making the luminous efficacy model a better alternative. Hence, this study attempted to model horizontal luminous efficacies under the 15 Commission internationale de l'éclairage (CIE) standard skies. Therefrom, daylight illuminance was estimated from a proposed vertical luminous efficacy model.

Measured solar irradiance, daylight illuminance and luminance distribution data were gathered from the local measuring station in Hong Kong. The luminance distribution data were used to classify the skies into the 15 CIE standard skies. Next, the solar irradiance and daylight data were used to derive the horizontal luminous efficacies under each standard sky. Furthermore, a vertical luminous efficacy model developed using the measured data was described, and this was used to predict vertical illuminance.

It was observed that Skies 1, 8 and 13 seem to be predominant in Hong Kong. Also, the result showed that constant luminous efficacies could be used for deriving illuminance data. Furthermore, horizontal luminous efficacy ranged from 40 to 190lm/W, indicating that daylight can provide sufficient visibility during working hours. The vertical luminous efficacy model proves to offer reasonable estimations of vertical illuminance data.

Further work needs to be done with more measured data to cover for spring seasons. The described model still needs to be fitted with different world climates to ascertain its universal applicability. The evaluations need to be done under obstructed sky conditions to cater for dense and clustered urban centres.

The discussed luminous efficacy model could be used to derive illuminance data in the absence of measured daylight illuminance data, especially in the subtropical region. Also, the comparative advantage of daylight over artificial lighting was highlighted in this study.

Unlike previous studies, this paper discusses the luminous efficacies of global, direct and diffuse components under the 15 CIE standard skies. Furthermore, the described luminous efficacy analysis provides an approach for deriving vertical and horizontal illuminance data. Such vertical data will be required for analysing building lighting requirements, sensible heat from electric lighting, and energy savings from daylighting controls. Also, the information on horizontal luminous efficacies will help evaluate solar roof and skylight designs.

The flux residues on almost all soldered printed circuit boards are removed using the chlorofluorocarbon (CFC) 113. In just one year's time production of this solvent will almost certainly be curtailed, on a scale agreed internationally. This is a major issue that needs to be addressed urgently by the electronics assembly industry worldwide. This paper presents (i) the background that has led to the restrictions being placed on production and consumption of solvent 113, (ii) the international agreement and timetable for the implementation of the restrictions and (iii) the perceived opportunities that are available to the electronics assembly industry to meet this challenge.