Space–time digital image analysis for granular flows

Intensification of the electrochemical production of chlorine and sodium hydroxide (i.e., the chlor-alkali process) was demonstrated in a centrifugal acceleration field. This intensification was shown by comparing the cell voltages and the anode potentials for a cell operated with and without a centrifugal field applied using the linear sweep voltammetric, galvanostatic and potentiostatic polarizations. Under industrial chlor-alkali electrolysis conditions, a cell voltage reduction of up to 600 mV and an anode potential reduction of up to 360 mV at 600 mA cm−2 were achieved by using a relative acceleration rate of 190 g with an acidic saturated NaCl solution at 80 °C. The relationships between the cell performance and relative acceleration rate, for different anode materials, temperature and NaCl concentration are reported.

Condensation Heat Transfer within a Circular Tube under Centrifugal Acceleration Field

We have developed a technique that utilizes electrolysis-generated pneumatic pressure and centrifugal force to achieve simple and reliable control over liquids in the microfluidic system of a rotating circular disk (CD). Specifically, this new technique was demonstrated for the propulsion of liquids in an upstream direction, against the centrifugal acceleration field, with control over their flow rates (metering). We also developed a simple mathematical model to describe the metering of said liquids as a function of electrical current flowing through an electrolyte (for generating pneumatic pressure) and also as a function of the angular frequency of rotation of the CD. A good correlation between the model and experimental data was achieved.

We applied a novel approach using still digital photography and image analysis to estimate emergence of bats at Tou Santi Cave, Dominica, West Indies. Although bat emergences are commonly studied, a population estimate of this lava tube has never been conducted. Known species inhabiting Tou Santi Cave include Brachyphylla cavernarum, Monophyllus plethodon, and Natalus stramineus. Using digital photography, we documented emerging bats at 30 second intervals for 130 minutes. Using image analysis software, we counted the number of bats in each frame and created 3 data sets. To find the total number of bats in each data set, multipliers were derived based on the 3 seconds it took the bats to pass from the bottom to the top of the framed area for the first 40 minutes, and 2 seconds for the remaining 90 minutes. The flight interval was a crucial element of this study. From these data we created 3 histograms to graphically summarize the number of emerging bats over time. The first 2 histograms represent bat counts at every 2 minutes. Combining all of the data to represent bat counts every minute resulted in a total estimate of 65,950 bats. Digital photography and image analysis software provide an efficient census technique for estimating the size of bat emergences.

SummaryObjective assessment of crop soil cover, defined as the percentage of leaf cover that has been buried in soil because of weed harrowing, is crucial to further progress in post‐emergence weed harrowing research. Up to now, crop soil cover has been assessed by visual scores, which are biased and context‐dependent. The aim of this study was to investigate whether digital image analysis is a feasible method to estimate crop soil cover in the early growth stages of cereals. Two main questions were examined: (i) how to capture suitable digital images under field conditions with a standard high‐resolution digital camera and (ii) how to analyse the images with an automated digital image analysis procedure. The importance of light conditions, camera angle, size of recorded area, growth stage and direction of harrowing were investigated, in order to establish a standard for image capture and an automated image analysis procedure based on the excess green colour index was developed. The study shows that the automated digital image analysis procedure provided reliable estimations of leaf cover, defined as the proportion of pixels in digital images determined to be green, which were used to estimate crop soil cover. A standard for image capture is suggested and it is recommended that digital image analysis be used to estimate crop soil cover in future research. The prospects of using digital image analysis in future weed harrowing research are discussed.

This letter addresses the application of Linear Dispersion Codes (LDC) in space and frequency domains in Single Carrier-Frequency Domain Equalization (SCFDE) systems. Space-frequency (SF)-LDCs are more suitable than space-time (ST) LDC in high mobility environments. However, the application of LDCs in space and frequency domains in SCFDE systems is not straightforward as in orthogonal frequency division multiplexing (OFDM) systems because in this case there is no direct access to subcarriers at the transmitter. This letter shows that it is possible to induce a target SF symbol dispersion in SCFDE by using a simple linear pre-coder and a conventional LDC that spreads the symbols in time and space domains according to specific ST dispersion matrices. The letter shows how to derive the ST dispersion matrices to be used at the transmitter as a function of the dispersion matrices describing the target SF dispersion. The presented procedure can be applied to both pure transmit diversity and pure multiplexing schemes, which are special cases of LDCs. Therefore, the proposed scheme provides a low complexity implementation of any dispersion in space and frequency over SCFDE systems, which alternatively would require the use of FFT/IFFT also at the transmitter side. The letter also shows a performance comparison of SF-LDCs and ST-LDCs in a typical propagation environment for future radio systems. The comparison confirms the suitability of using the dispersion in frequency rather than time for a wide range of coherence bandwidths.

Quantifying fungal infection of plant leaves by digital image analysis using Scion Image software

Centrifuge model studies on desiccation cracking behaviour of fiber-reinforced expansive clay

Разработано программное обеспечение ImgOpinion, которое позволяет выполнять оптико-структурный анализ цифрового изображения объекта методами компьютерного зрения. Оно предназначено для использования в экспертных лабораториях в составе аппаратно-программного комплекса компьютерного зрения MS-Unit, который включает специализированный осветитель “Фотобокс 3138” с цифровой регистрирующей камерой. Выходные данные строятся в виде цифрового паспорта огнестрельного повреждения, в котором приводятся криминалистически значимые характеристики объекта исследования, а также выявленных на нем следов выстрела. The ImgOpinion software, capable to perform the optical and structural analysis of a digital image of the object by computer vision methods, was developed. It can be employed in expert laboratories as a part of the computer vision hardware-software complex MS-Unit together with specialized illuminator “Photobox 3138” with a digital recording camera. The output data is constructed in the form of a digital passport of the gunshot residue, which contains forensically significant characteristics of the object under investigation, as well as a gunshot residue detected on it. Purpose. The research has solved the problem of creating a specialised hardware and software complex for forensic examination, the use of which partially automates the processes of identification and quantitative characterisation of gunshot traces and products. Methodology. Non-destructive research methods are implemented in computer vision systems, which include two main stages: a digital image acquisition and its mathematical processing. The hardware and software complex of a computer vision usually consists of an illuminator, a digital recording video camera and a specialised program for processing the raw data. Findings. ImgOpinion software has been developed, which allows performing the optical-structural analyses of digital images using the computer vision methods and is intended for use in expert laboratories as part of the MS-Unit computer vision hardware and software complex, which includes a specialized illuminator “Photobox 3138” with a digital recording camera. Autonomous and portable device has a mobile design and provides white light with colour temperature 5000 K (CIE D50) and colour rendering index CRI = 97+. Six independently switched LED monochrome illuminators with narrow spectral bands from 365 to 880 nm (UV to IR spectral bands) provide the uniform illumination without extraneous stray light on the working field (light intensity drop below 2 % at the edges of the working field). Value. The ImgOpinion output is constructed in the form of a digital passport of a gunshot injury, which contains forensically relevant characteristics of the object of investigation. The digital passport is an adaptation of the forensically significant information on the firearm traces for the integration into specialized databases for further development of the automation of expert evaluation processes, conducting the automated trace comparison and the determination of incident circumstances by it.

Studies were conducted to compare visual estimates of ground cover and canopy cover by both inexperienced and experienced observers and to compare those estimates with those from more objective methods in native pastures in the high rainfall, temperate rangelands of northern NSW. Ground cover and canopy cover of 60 quadrats was estimated using visual, mapped area, digital image analysis and photo point quadrat methods. Inexperienced observers were trained by estimating ground cover of reference quadrats. Differences between mean visual estimates of ground cover and canopy cover for experienced and inexperienced observers were not significant ( P >0.05). Mean ground cover estimates by the mapped area, digital image analysis and point quadrat methods were also not different from each other. The overall relationship between mean visual estimate and mean objective estimate of ground cover was non-linear (second order polynomial, R2 = 0.93), observers tending to underestimate in the mid-range (20 to 80%) of cover compared with objective methods. Mean visual estimate of ground cover was 73.7% compared with the mean objective estimate of 83.7%. Visual estimates of canopy cover (mean 34.6%) were highly correlated (R2 = 0.90) with those of the mapped area method (mean 34.3%) and the relationship was linear. Measurement of ground cover is a standard technique used in many pasture ecology and management studies and is increasingly being used by land managers to monitor pasture production and sustainability. Inexperienced observers were trained quickly and easily to estimate ground cover and canopy cover with sufficient accuracy to identify ranges of cover using visual estimation, indicating that the visual estimation technique should be suitable for estimating ground cover in land management research.

The coverage extent and intensity of apple blush are important factors in the evaluation of apple fruit quality for some cultivars. We analyzed blush coverage extent and intensity in the cultivar Honeycrisp to 1) define categories of marketable blush in terms relating to device-independent color measurements; 2) assess relationships among a modified anthocyanin index (AI m ) calculated from spectral measurements, colorimetry (CO), and human judgment of apple blush intensity; 3) assess the efficacy of digital image analysis (DIA) of color-calibrated digital photography as a tool to measure blush coverage extent; and 4) explore differences between human judgment of blush coverage extent and DIA. AI m and CO were both effective in providing statistical categorical separation among five classes of apple blush in ‘Honeycrisp’: “non-blush,” “slight non-marketable blush,” “minimum quality marketable blush,” “clear marketable blush,” and “outstanding blush” as judged by human participants. The boundary between blush and non-blush was judged to be a hue angle less than 49.0 ± 3.1 h ab in CIELAB L*C ab *h ab color space and an AI m value greater than 4.3 ± 1.3 at α < 0.05. DIA was less sensitive and did not show statistically significant differences between “clear marketable blush” and “outstanding marketable blush,” although its use to distinguish the other categories was successful. All methods of analysis resulted in high agreement with respect to the blush/non-blush boundary (Cohen's kappa ≥ 0.897).

This paper reports experimental findings on the flow of sand down a steep chute. Nearly all granular flow models have a maximum value for the friction and therefore predict that flows on steep slopes will accelerate at a constant rate until the interaction with the ambient fluid becomes important. This prediction has not been tested by previous work, which has focused on relatively low slope angles where steady, fully developed flows occur after short distances. We test this by investigating flows over a much greater range of slope angles (30–50${}^{\ensuremath{\circ} } $) and flow depths (4–130 particle diameters). We examine flows with two basal conditions, one flat and frictional, the other bumpy. The latter imposes a no-slip condition for slow, deep flows, but permits some degree of slip for high flow velocities. The data suggests that friction can be much larger than theories such as the $\ensuremath{\mu} (I)$ rheology proposed by Jop, Forterre & Pouliquen (Nature, vol. 441, 2006) suggest and that there may be constant velocity states above the angle of vanishing ${h}_{\mathit{stop}} $. Although these flows do not vary in time, all but the flows on the bumpy base at low inclinations accelerate down the slope. A recirculation mechanism sustains flows with a maximum mass flux of $20~\mathrm{kg} ~{\mathrm{s} }^{\ensuremath{-} 1} $, allowing observations to be made at multiple points for each flow for an indefinite period. Flows with Froude number in the range 0.1–25 and bulk inertial number 0.1–2.7 were observed in the dense regime, with surface velocities in the range 0.2–5.6 $\mathrm{m} ~{\mathrm{s} }^{\ensuremath{-} 1} $. Previous studies have focused on $I\lessapprox 0. 5$. We show that a numerical implementation of the $\ensuremath{\mu} (I)$ rheology does not fully capture the accelerating dynamics or the transverse velocity profile on the bumpy base. We also observe the transverse separation of the flow into a dense core flanked by dilute regions and the formation of longitudinal vortices.

Catastrophic dense granular flows, such as occur in rock avalanches, debris flows and pyroclastic flows, move as fully shearing mixtures that have approximately 60 vol.% solids and tend to segregate to form coarse-grained fronts and leveed channels. Levees restrict spreading of unconfined flows and form as coarse particles that become concentrated in the top of the flow are transported to the front and then advect to the sides in the flow head. Channels from which most material has drained away down slope are commonly lined with fine-grained deposit, widely thought to remain from the tail of the waning flow. We show how segregation in experimental dense flows of carborundum or sand (300–425 μm) mixed with spherical fine ballotini (150–250 μm), on rough slopes of 27–29°, produces fine-grained channel linings that are deposited with the levees, into which they grade laterally. Maximum runout distance is attained with mixtures containing 30–40% sand, just sufficient to segregate and form levees that are adequately robust to restrict the spreading attributable to the low-friction fines. Resin impregnation and serial sectioning of deliberately arrested experimental flows shows how fines-lined levees form from the flow head; the flows create their own stable ‘conduit’ entirely from the front, which in a geophysical context can play an important mechanistic role in facilitating runout. The flow self-organization ensures that low-friction fines at the base of the segregated channel flow shear over fine-grained substrate in the channel, thus reducing frictional energy losses. We propose that in pyroclastic flows and debris flows, which have considerable mobility attributable to pore-fluid pressures, such fine-grained flow-contact zones form similarly and not only reduce frictional energy losses but also reduce flow–substrate permeability so as to enhance pore-fluid pressure retention. Thus the granular flow self-organization that produces fine-grained channel linings can be an important factor in facilitating long runout of catastrophic geophysical flows on the low slopes (few degrees) of depositional fans and aprons around mountains and volcanoes.

A photographic survey of 43 multiparous lactating cows was carried out by recording the images between morning and evening milking time (around noon time) using digital camera from posterior angle. Images were then processed using Image Tools V.3.00 software to determine Udder measurements (UMs) of cows from the images in centimetres. The linear parameters recorded were rear udder depth (UD), rear udder width (UW) and rear udder area (UA). Regression analysis of milk yield on each of the independent variables was performed. Regression coefficients, for all UMs, taken together were 65.5%. The single regression coefficients were 23.0, 0.2 and 61.0for UD, UW and UA, respectively. The correlation coefficients between milk yield and UD, UW and UA were 0.48 (P >0.05), 0.04 (P >0.05) and 0.78 (P <0.05), respectively. The results showed that, the milk yieldof cows could be predicted using digital image, using udder area as a parameter. However, the prediction possibility was higher when all UMs were used.

It is a well-established argument that side-wall interface friction can influence the behaviour of soil located at the boundary of physical model test chambers. This effect has a potentially significant influence on measurement techniques such as particle image velocimetry that often rely on images captured at vertical transparent boundaries. However, it is hypothesised that under kinematically controlled boundary conditions, particle image velocimetry can yield not only qualitative but highly accurate quantitative measurements of deformation. In this paper, this hypothesis is tested for the specific soil–structure interaction problem of pipelines being subject to vertical faulting. In the middle of the model, a circular model pipeline was heavily instrumented with 32 pairs of strain gauges. At the same elevation but at the window of the test chamber, an identical model pipeline was split in half axially along its centreline to give a semi-circular cross-section, and placed against the visible window. Three digital cameras were used to record deformations of the pipe and the surrounding soil during the test. After image processing and filtering, measurements of peak curvature obtained from digital image analysis on the half pipeline section are shown to be within 5% of the results obtained from strain gauges.