specially designed mechanical spring and some electrical switch valves. The diﬀerence in pressure between the liquid supply tank and the vacuum chamber is used to absorb fresh dielectric liquid into the vacuum chamber. When the liquid is reﬁlled, the switch valves are deactivated and the spring pushes the injection cylinder back to its original position. The sampling unit, including a suspension container, a sample- collecting container, a specially designed temperature-con- trol ring and some switch valves, is used to perform the sampling operation by controlling the pressure diﬀerence between the vacuum chamber and the collecting container and keeping the temperature of the suspension well under the liquid vaporization temperature. The particlesizing unit, consisting of a Horiba particle analyzer, some liquid-trans- ferring PU (Polyurethane) pipes and switch valves, is deployed to measure secondary particle size and the results are transferred to the PC for data storage and further analysis. The method for extracting nanoparticle suspension from the vacuum chamber into the sample-collecting container is based on the pressure diﬀerence between the working chamber and the container, which is employed as the extracting force to remove nanoparticle suspension sample from the vacuum chamber. It is also important to maintain a constant temperature of liquid sample along its transferring path for preventing sample vaporization due to liquid phase transformation.
Abstract. In situ observations from research aircraft and in- strumented ground sites are important contributions to devel- oping our collective understanding of clouds and are used to inform and validate numerical weather and climate models. Unfortunately, biases in these datasets may be present, which can limit their value. In this paper, we discuss artefacts which may bias data from a widely used family of instrumentation in the field of cloud physics, optical array probes (OAPs). Using laboratory and synthetic datasets, we demonstrate how greyscale analysis can be used to filter data, constraining the sample volume of the OAP and improving data quality, par- ticularly at small sizes where OAP data are considered unre- liable. We apply the new methodology to ambient data from two contrasting case studies: one warm cloud and one cirrus cloud. In both cases the new methodology reduces the con- centration of small particles (<60 µm) by approximately an order of magnitude. This significantly improves agreement with a Mie-scattering spectrometer for the liquid case and with a holographic imaging probe for the cirrus case. Based on these results, we make specific recommendations to in- strument manufacturers, instrument operators and data pro- cessors about the optimal use of greyscale OAPs. The data from monoscale OAPs are unreliable and should not be used for particle diameters below approximately 100 µm.
If the current solution is convergent, then the iteration will stop. We do not know whether the final value is the best value. Below are the stopping criteria conditions for the iteration: First, terminate when a maximum number of iterations, or FEs, has been exceeded. Second, Terminate when an acceptable solution has been found, Third, Terminate when no improvement is observed over a number of iteration. Fourth, terminate when the normalized swarm radius is close to zero. Fifth, terminate when the objective function slope is approximately zero. Although the particle has stopped, we do not know whether the particle will pitch on local optima, local minima, global optima or global optima.
counter occurred during the Southern African Regional Science Initiative (SAFARI) 2000 (Haywood et al., 2003b). The Puerto Rico Dust Experiment (PRIDE) took place in the Caribbean in June/July 2001. Data from a light aircraft, remote sensing and ground-based measurements were used to study the dust after the transport across the Atlantic into the Caribbean region (Reid et al., 2003b; Maring et al., 2003b). One result of PRIDE was the discovery of particles larger than consistent with Stokes gravitational settling (Maring et al., 2003a). Assuming a continuous upward velocity of 0.33 cm s -1 , the authors could explain the existence of the large particles. However, Maring et al. (2003a) were not sure which physical process(es) caused the hypothesised upward velocity that partly counteracted the gravitational settling. Reid et al. (2003a) compared size and morphological measurements of coarse mode dust particles from Africa gathered during PRIDE and found large differences between optical particle counters and aerodynamic methods. Both experiments, SHADE 2000 and PRIDE 2001, took place in the outflow area of dust on Cape Verde, several hundreds of km away from the major dust sources so that the dust properties may have been transformed during transport. The results of SAFARI, SHADE and PRIDE suggest that there is still a need for the exact quantification of the dust size distribution up to sizes of 100 µm. One possibility to gather data on the particle size distribution of Saharan/Sahelian dust was given by the African Monsoon Multidisciplinary Analysis (AMMA) 2006 field study. However, this large international experiment focussed mainly on the understanding of dynamical processes such as tropical thunderstorms and the African Monsoon, and involved only a minor airborne aerosol component.
Research over the last decade has shown that the suspended sediment loads of many rivers are dominated by composite particles. These particles are also known as aggregates or flocs, and are commonly made up of constituent mineral particles, which evidence a wide range of grain sizes, and organic matter. The resulting in situ or effective particle size characteristics of fluvial suspended sediment exert a major control on all processes of entrainment, transport and deposition. The significance of composite suspended sediment particles in glacial meltwater streams has, however, not been established. Existing data on the particle size characteristics of suspended sediment in glacial meltwaters relate to the dispersed mineral fraction (absolute particle size), which, for certain size fractions, may bear little relationship to the effective or in situ distribution. Existing understanding of composite particle formation within freshwater environments would suggest that in-stream flocculation processes do not take place in glacial meltwater systems because of the absence of organic binding agents. However, we report preliminary scanning electron microscopy data for one Alpine and two Himalayan glaciers that show composite particles are present in the suspended sediment load of the meltwater system. The genesis and structure of these composite particles and their constituent grain size characteristics are discussed. We present evidence for the existence of both aggregates, or composite particles whose features are largely inherited from source materials, and flocs, which represent composite particles produced by in- stream flocculation processes. In the absence of organic materials, the latter may result solely from electrochemical flocculation in the meltwater sediment system. This type of floc formation has not been reported previously in the freshwater fluvial environment. Further work is needed to test the wider significance of these data and to investigate the effective particle size characteristics of suspended sediment associated with high concentration outburst events. Such events make a major contribution to suspended sediment fluxes in meltwater streams and may provide conditions that are conducive to composite particle formation by flocculation. Copyright 2002 John Wiley & Sons, Ltd.
Acquiring the hydrated particle properties is far from triv- ial, especially when it comes to vertical profiling. In situ tech- niques can provide vertically resolved information when ap- plied by an airborne platform, a solution that yields detailed information for particle properties despite being costly and sparse over space and time. Unfortunately, the commonly used in situ techniques can cause alterations in the parti- cle ambient state even when minimally invasive instruments are used (e.g., open-path optical sensors; Snider and Pet- ters, 2008). To address these biases, ambient particle sam- ples are first dried and then rehydrated in the controlled envi- ronment of an in situ sensor; aerosol properties and changes thereof are then used to understand the behavior of ambi- ent aerosol for any meteorological state (Engelhart et al., 2011; Pikridas et al., 2012). In contrast to in situ techniques, remote sensing is not invasive and may sample large at- mospheric volumes, enabling an unprecedented spatial and temporal coverage for global aerosol monitoring. Passive remote sensing techniques provide columnar particle prop- erties, while active sensors can provide vertically resolved properties. A well-known active remote sensing instrument is the lidar (light detection and ranging), a sensor that is ca- pable of acquiring vertical profiles of the backscatter and extinction coefficients at one or more wavelengths. The ill- posed nature of the aerosol property retrieval remains the inherent disadvantage of the lidar technique, although con- siderable algorithmic developments have been achieved over the last decade. These include the employment of sophisti- cated multi-wavelength elastic/Raman lidar measurements in lidar stand-alone retrievals (e.g., Müller et al., 2016) or the combination of elastic lidar with sun-photometer measure- ments (e.g., Chaikovsky et al., 2016; Lopatin et al., 2013). Although these advancements have provided means towards more accurate aerosol profiling, still the lidar stand-alone re- trievals work well only for fine particles while the lidar/sun- photometer retrievals do not fully resolve the particle micro- physical property profiles; they instead provide only the par- ticle concentration profile and consider a constant size dis- tribution and refractive index for the whole atmospheric col- umn.
laser power with a variable interval 0.07-2 W to investigate particles with the radius of 90nm;they observed the variation in the autocorrelation function with increasing the incident laser power and pointed that the variation was resulted from the laser-induced motion of scattering particles. In the research of determining nano-particles size in a suspension with low concentration, Kuyper et al. focused a laser light to an avalanche photodiode that has high sensitivity to light source; particles with different diameters were studied for a number of tests. Their analysis showed that in the power changed from 300 to 900μW, there was a linear increase in the measured diffusion time. They then concluded that the measured particle size using DWS appeared to be power-dependent; for particles with a moderate size, low excitation power was sufficient to provide an accurate size measurement, but low power laser illumination could be a problem for smaller and less bright particles. Harada et al. found the similar results; when using an Argon laser beam to illuminate a sample cell, they found that, with the laser power adjusted from 0 to 60mW and under improper laser power, the resultant particle size was larger than it should be, and the increase in particle size or laser radiation resulted in larger difference between true and measured sizes.
The two levels of Distributed Generation technologies is local level and end point level. Local level power generation plant is the renewable technologies such as wind turbines, solar system, geothermal energy and biomass. This type of plant is smaller and more efficient also less environmentally damaging or disrupting energy than the centralized power model. For the end point level mostly is the internal combustion engine. The categories of DG that had been suggested by author  are as shown in Table 1. In other words, demand-side resources not only based on local generation within distribution system on customers side but also mean to reduce customer demand. To give the maximum use of DG, it has to be installed with optimum sizing and suitable location. Fail to do so will make load node voltage along the feeder to increase.
Abstract: This research investigates the use of charge coupled device (abbreviated as CCD) linear image sensors in an optical tomographic instrumentation system used for sizing particles. The measurement system, consisting of four CCD linear image sensors are configured around an octagonal shaped flow pipe for a four projections system is explained. The four linear image sensors provide 2,048 pixel imaging with a pixel size of 14 micron × 14 micron, hence constituting a high-resolution system. Image reconstruction for a four-projection optical tomography system is also discussed, where a simple optical model is used to relate attenuation due to variations in optical density, [R], within the measurement section. Expressed in matrix form this represents the forward problem in tomography [S] [R] = [M]. In practice, measurements [M] are used to estimate the optical density distribution by solving the inverse problem [R] = [S] −1 [M]. Direct inversion of the sensitivity matrix, [S], is not possible and two approximations are considered and compared—the transpose and the pseudo inverse sensitivity matrices.
The shape and size of nanoparticles are important parameters affecting the biodistribution, bioactivity, and toxicity. The high-throughput characterisation of nanoparticle shape in the dispersion is a fundamental prerequisite for realistic in vitro and in vivo evaluation, however, with routinely available bench-top optical characterisation techniques, it remains a challenging task. Herein, we demonstrate the efficacy of Single Particle Extinction and Scattering (SPES) technique for the in situ detection of the shape of nanoparticles in dispersion, applied to a small library of anisotropic gold particles, with potential developments of in-line detection. The use of SPES paves the way to the routine quantitative analysis of nanoparticles dispersed in biologically relevant fluids, which is of importance for the nanosafety assessment and any in vitro and in vivo administration of nanomaterials.
Biodegradable injectable in situ gel forming drug delivery systems represent an attractive alternative to microspheres and implants as parenteral depot systems. It consists of biodegradable polymers dissolved in a biocompatible carrier. When the liquid polymer system is placed in the body using standard needles and syringes, it undergoes solidification upon contact with aqueous body fluids to form solid implant. If a drug is incorporated into the polymer solution, it becomes entrapped within polymer matrix as it solidifies. Drug release occurs over time as polymer biodegrades. Biodegradable polymers used in these systems are polyanhydrides, polyhydroxy acids, polyesteramides, polyorthoesters and others  . Chitosan (CS) is an amino-
The calibrated data can be seen to extend to much larger diameters than that processed using the manufacturer’s spec- ification. This is mostly due to the impact of the different refractive index of the measured dust compared to the refrac- tive indices of PSL spheres and water droplets referenced by the manufacturer. The two instruments are in excellent agree- ment where they meet and any discontinuity is much less than the 1-sigma error bars plotted. Some bumps seen in the PCASP distribution have been accentuated by the calibration and refractive index correction presented here. It could be the case that these are real modes or there is the potential that this is an artefact caused by imperfect knowledge of the particle scattering properties. The error bars are a significant fraction of the mode height so the statistical significance of this peak is not clear. A strong advantage of the methods used here is the derivation of error bars for this plot which are traceable and transparent which allow consideration of the statistical significance of such modes.
Particle size distribution is a crucial property in particulate processes and it a ff ects a lot of quantities - flow of sus- pension, dispersion, eventuallly separation processes, mass transfer etc. This contribution is focused on in-situ mea- surements and evaluation of particle size distribution of suspended solid spherical particles and spherical droplets of oil in water-oil dispersion. The dispersions were pro- cessed in an agitated vessel. These investigated processes are commonly used in chemical or metallurgical industry (e.g. extraction, catalytic reactions, polymerization etc.). The dynamic evolution of droplet size distribution in time inside an agitated vessel has been investigated by many re- searchers [1–5]. They tried to develop a simple model of droplet size distribution developing in time and depend- ing on parameters of the mixing system. The agitated ves- sel geometry or impeller types were also examined [5,4]. Several approaches applying of population balance mod- elling [6–9] were used. The generalized equation of popu- lation balance can be used to solve grow of crystals (molec- ular transport, nucleation, breakage, aggregation), aggre- gation process of solid particles in fluid, liquid-liquid dis- persion process and many others. The method is based on the solution of integro-differential equations with proba- bility density functions. There are many methods how to solve population balance, one of the commonly used is the QMOM (Quadrature method of moments) based on quadrature approximation [10,11] which can be very eas- ily implemented to existing solvers based on finite volume method. Hence it is used in coupling with CFD (Compu- tational fluid dynamics). The coupling is based on media transport, application of turbulence diffusion as well as ap- plication of dissipation rate of turbulent kinetic energy in breakage kernel functions. The main aim of our investi- gation is development of very precise measurement of the
ABSTRACT: Growing concerns over environmental impacts, conditions for improvement of the whole distribution network, and rebate programs offered by governments have contributed to an increment in the number of DG units in commercial and domestic electrical power output. It is known that the non optimal size and non optimal placement of DG units may lead to high power losses, bad voltage profiles. Therefore, this paper introduces a sensitivity analysis to determine the optimal sitting and sizing of DG units. A new methodology PSO for the placement of DG in the radial distribution systems to reduce the active power losses and to improve the voltage profile. A two-stage methodology is practiced for the optimal DG placement. In the first stage Power System Analysis Toolbox (PSAT), an open source MATLAB software package for analysis and design of small to medium size electric power systems for power flow and in the second stage, PSO is used to find the optimal size and site of DG in distribution systems. The effectiveness of the proposed method is demonstrated through IEEE 15-bus standard test systems.
Abstract: Battery energy storage system (BESS) plays an important role in peak load sharing, providing real power regulating capacity and improving voltage quality. In isolated micro grids, balancing the energy demand is a critical issue, due to the presence of intermittent energy sources. BESS can be installed in such circumstances to supply the demand and act as a spinning reserve for an isolated micro grid. The integration of BESS and renewable energy sources with the existing distribution networks has many challenges. One of the major challenges is to determine the size and allocation of the BESS in the distribution system. However, due to the high installation costs and less life of BESS, there is a need for proper method to select such systems and size them optimally. In this paper, a stand-alone micro grid with Solar, Wind, Diesel and battery sources are considered. An optimization methodology for BESS using Particle Swarm Optimization (PSO) is applied which gives optimal battery capacity with minimum cost, good reliability and lower pay back periods. The proposed methodology for optimization is tested on three case studies and the results are validated.
The empirical method for SPM was validated fol- lowing the methodology of matching satellite and field data suggested by Bailey and Werdell (2006). A ±5-h temporal window between the satellite overpass and the in situ measurements (due to the presence of clouds it could not be shortened) and a spatial box of 3×3 pixels were used. As a test of homogeneity, and to minimize the impact of the variability of the geophysical variable in the satellite pixel box, the coefficient of variation (CV), defined as the ratio between the standard devia- tion and the average, was used. A limit of CV=0.2 was chosen, thus excluding all satellite boxes showing CV values larger than 0.2. Level 1A MODIS-Aqua images (1.1 km spatial resolution) were downloaded from the NASA ocean colour website (https://oceancolor.gsfc. nasa.gov/). Images were processed using the freely available SeaDAS 7.02 software to obtain remotely sensed reflectance (R rs ) using the NIR-SWIR switching
The study of geotechnical index properties of soils in Warri, Delta state was carried out to determine the index properties of soil. The laboratory test carried out included, moisture content, grain size analysis, Atterberg limits and compaction test. These results indicate that the soil is poorly graded, well drained, it is of intermediate plasticity, medium swelling potential. The results of particle grain size distribution test show that the soil sample is mainly sand. This means that they will tend to increase in compressibility and decrease in shear strength. Also, as a result of their poorly graded nature, they will have negative effects such as high effective porosity, large mean pore size, how density and high permeability. The compaction results show that the maximum dry density (MDD) and the optimum moisture content (OMC).
Sizing Up Lincoln Financial Sizing Up Lincoln Financial | 1 Sizing Up Lincoln Financial By Kerry Pechter Thu, Jan 23, 2020 Over the past 40 years, events and trends have helped determine Lincoln Finan[.]
Two methods have been described here for calibrating opti- cal particle counters (OPCs) which are based on the principle that an OPC measures an electrical pulse height which is re- lated to a particle’s scattering cross section. The two methods are referred to as the discrete and scanning methods. The dis- crete method utilises particle samples available only at a fi- nite number of different diameters, and fits a sensitivity curve between the pulse height measured by the OPC and the scat- tering cross section of the particles. This method requires the user to have some access to the pulse heights measured by the OPC, and has been used to calibrate a Passive Cavity Aerosol Spectrometer Probe (PCASP) and a Cloud Droplet Probe (CDP). The scanning method can be used when OPC pulse heights are not accessible but requires a sample size distribution which can be adjusted in a continuous manner. The PCASP has been calibrated using this method with a differential mobility analyser (DMA). The DMA provides a continuously adjustable sample of DEHS oil aerosol with mode diameter, D ∗ , up to 0.5 µm. A sigmoid-type function was fitted giving the fraction of particles larger than a given bin boundary, F , as a function of D ∗ . The diameter equiva- lent of the bin boundary is given by the value of D ∗ where F is equal to 0.5.