A Simple Theory and Performance Prediction for a Shrouded Wind Turbine with a Brimmed Diffuser

We developed a new wind turbine system that consists of a diffuser shroud with a broad-ring brim at the exit periphery and a wind turbine inside it. The shrouded wind turbine with a brimmed diffuser, which we called a “wind lens turbine” (WLT), has demonstrated power augmentation by a factor of about 2–5 compared with a bare wind turbine for a given turbine diameter and wind speed. The increase in power output depends on the diffuser shape and length and the brim height. However, a simple theory presented in this paper argues that only two performance coefficients are needed to predict the performance of WLT. The coefficients are the back pressure coefficient of the brim and the pressure recovery coefficient of the diffuser. We theoretically showed that the back pressure coefficient was particularly important for the performance of WLT. Finally, the simple theory was evaluated with experimental results. The results showed good agreement with each other.

New Interpretation of X-ray Diffraction Pattern of Vitreous Silica

The striking feature of X-ray diffraction pattern of vitreous silica is that the center of its intense but broad ring is located at nearly the same position as the strongest diffraction ring of β-cristobalite. Two fundamentally different explanations to the diffraction patterns were appeared about 90 years ago, one based on the smallest crystals of β-cristobalite and the other based on the non-crystalline continuous random network. This work briefly outlines the facts supporting and objecting these two hypotheses, and aims to present a new interpretation based on a medium-range ordering structure on the facets of clusters formed in the glass transition process. It will be shown that the new interpretation provides a more satisfactory explanation of the diffraction pattern and physical properties of silica glass, and offers considerable valuable information regarding the nature of glass and glass transition.

On ring solutions of neural field equations

The article is devoted to investigation of integro-differential equation with the Hammerstein integral operator of the following form: ∂_t u(t,x)=-τu(t,x,x_f )+∫_(R^2)▒〖ω(x-y)f(u(t,y) )dy, t≥0, x∈R^2 〗. The equation describes the dynamics of electrical potentials u(t,x) in a planar neural medium and has the name of neural field equation.We study ring solutions that are represented by stationary radially symmetric solutions corresponding to the active state of the neural medium in between two concentric circles and the rest state elsewhere in the neural field. We suggest conditions of existence of ring solutions as well as a method of their numerical approximation. The approach used relies on the replacement of the probabilistic neuronal activation function f that has sigmoidal shape by a Heaviside-type function. The theory is accompanied by an example illustrating the procedure of investigation of ring solutions of a neural field equation containing a typically used in the neuroscience community neuronal connectivity function that allows taking into account both excitatory and inhibitory interneuronal interactions. Similar to the case of bump solutions (i. e. stationary solutions of neural field equations, which correspond to the activated area in the neural field represented by the interior of some circle) at a high values of the neuronal activation threshold there coexist a broad ring and a narrow ring solutions that merge together at the critical value of the activation threshold, above which there are no ring solutions.

Annular substructures in the transition disks around LkCa 15 and J1610

We present high-resolution millimeter continuum ALMA observations of the disks around the T Tauri stars LkCa 15 and 2MASS J16100501-2132318 (hereafter, J1610). These transition disks host dust-depleted inner regions, which have possibly been carved by massive planets, and they are of prime interest to the study of the imprints of planet-disk interactions. While at moderate angular resolution, they appear as a broad ring surrounding a cavity, the continuum emission resolves into multiple rings at a resolution of ~60 × 40 mas (~7.5 au for LkCa 15, ~6 au for J1610) and ~7 μJy beam−1 rms at 1.3 mm. In addition to a broad extended component, LkCa 15 and J1610 host three and two narrow rings, respectively, with two bright rings in LkCa 15 being radially resolved. LkCa 15 possibly hosts another faint ring close to the outer edge of the mm emission. The rings look marginally optically thick, with peak optical depths of ~0.5 (neglecting scattering), in agreement with high angular resolution observations of full disks. We performed hydrodynamical simulations with an embedded, sub-Jovian-mass planet and show that the observed multi-ringed substructure can be qualitatively explained as the outcome of the planet-disk interaction. We note, however, that the choice of the disk cooling timescale alone can significantly impact the resulting gas and dust distributions around the planet, leading to different numbers of rings and gaps and different spacings between them. We propose that the massive outer disk regions of transition disks are favorable places for planetesimals, and possibly second-generation planet formation of objects with a lower mass than the planets carving the inner cavity (typically few MJup), and that the annular substructures observed in LkCa 15 and J1610 may be indicative of planetary core formation within dust-rich pressure traps. Current observations are compatible with other mechanisms contributing to the origin of the observed substructures, in particular with regard to narrow rings generated (or facilitated) at the edge of the CO and N2 snowlines.

A new species of Pyrrhosphodrus (Hemiptera: Heteroptera: Reduviidae) from the Caatinga ecosystem in Brazil, with notes on the genus

A new species of Reduviidae (Hemiptera: Heteroptera) from Caatinga ecosystem, Pyrrhosphodrus caatingensis Lapischies & Forero sp. nov., is described. The new species is distinguished from its congeners by its overall reddish coloration with black areas; by the black legs, with femora with a subapical yellowish broad ring, tibiae with apical and subapical yellowish annuli; and genital characters. Comments about the biology, feeding habits, habitus, genitalic images, and a distribution map of the new species are given. In addition, the following synonymy is proposed: Pyrrhosphodrus militaris Stål, 1866 = P. theresina (Berg, 1879), syn. nov. A key to separate the known species of Pyrrhosphodrus Stål, 1866 is provided.

Probing midplane CO abundance and gas temperature with DCO+ in the protoplanetary disk around HD 169142

Context. Physical and chemical processes in protoplanetary disks affect the disk structure and the midplane environment within which planets form. The simple deuterated molecular cation DCO+ has been proposed to act as a tracer of the disk midplane conditions. Aims. This work aims to understand which midplane conditions are probed by the DCO+ emission in the disk around the Herbig Ae star HD 169142. We explore the sensitivity of the DCO+ formation pathways to gas temperature and CO abundance. Methods. The DCO+ J = 3−2 transition was observed with Atacama Large Millimeter/submillimeter Array at a spatial resolution of ~0.3′′ (35 AU at 117 pc). We modeled the DCO+ emission in HD 169142 with a physical disk structure adapted from the literature, and employed a simple deuterium chemical network to investigate the formation of DCO+ through the cold deuterium fractionation pathway via H2D+. Parameterized models are used to modify the gas temperature and CO abundance structure of the disk midplane to test their effect on DCO+ production. Contributions from the warm deuterium fractionation pathway via CH2D+ are approximated using a constant abundance in the intermediate disk layers. Results. The DCO+ line is detected in the HD 169142 disk with a total integrated line flux of 730 ± 73 mJy km s−1. The radial intensity profile reveals a warm, inner component of the DCO+ emission at radii ≲30 AU and a broad, ring-like structure from ~50–230 AU with a peak at 100 AU just beyond the edge of the millimeter grain distribution. Parameterized models show that alterations to the midplane gas temperature and CO abundance are both needed to recover the observed DCO+ radial intensity profile. The alterations are relative to the fiducial physical structure of the literature model constrained by dust and CO observations. The best-fit model contains a shadowed, cold midplane in the region z∕r < 0.1 with an 8 K decrease in Tgas and a factor of five CO depletion just beyond the millimeter grains (r = 83 AU), and a 2 K decrease in Tgas for r > 120 AU. The warm deuterium fractionation pathway is implemented as a constant DCO+ abundance of 2.0 × 10−12 between 30–70 K and contributes >85% to the DCO+ emission at r < 83 AU in the best-fit model. Conclusions. The DCO+ emission probes a reservoir of cold material in the HD 169142 outer disk that is not probed by the millimeter continuum, the spectral energy distribution, nor the emission from the 12 CO, 13 CO, or C18O J = 2−1 lines. The DCO+ emission is a sensitive probe of gas temperature and CO abundance near the disk midplane and provides information about the outer disk beyond the millimeter continuum distribution that is largely absent in abundant gaseous tracers such as CO isotopologues.

Effect of Dispersion Medium and Dominated Evaporation on the Pattern Formation of Colloidal Suspension

We study the effect of dispersion medium and dominated evaporation on the drying process and pattern of thin liquid layer colloidal suspention. Panasonic camera is used to capture the drying process and macroscopic pattern. It is shown that drying patterns are sensitive to the dispersion medium. As the volume ratio of ethanol in aqueous ethanol colloidal suspension increases, the evaporation rate increases, and film in the center becomes smaller and thinner, obvious broad-ring pattern can be observed. We suggest that difference in dispersion medium changes the evaporation rate, which has a direct proportional variation with strength of Marangoni convection. Furthermore, convection strength has great influence on self-assembly of colloid particles and the pattern formation of colloidal suspension. We design two simple experiments to change the evaporation rate and convection strength in order to verify the conclusion above. Broad-ring patterns with spray-like round edge at higher evaporation rate are obtained. Uniform film forms at lower evaporation rate.

Excavation of a Neolithic enclosure and an Iron Age settlement at Douglasmuir, Angus

The complete excavation of a post-defined Neolithic enclosure took place in 1979 and 1980 in advance of the construction of a gas compressor station for the British Gas Corporation. The enclosure appeared to have been constructed in two parts. There was little evidence for any associated activity except for a pit in the north half. Three charcoal samples from the post-holes produced radiocarbon dates in the range 3930-3390 cal BC. A small sample of a scatter of pits visible on aerial photographs was also excavated. Six penannular ring-ditch houses dating to the mid first millennium BC were also investigated. The houses were of the broad ring-ditch type with internal ring beam support. Other features included six-post structures and crescent-shaped hollows which might be the truncated remains of further house sites. There was little horizontal stratigraphy. The project was arranged and funded by Historic Scotland and its predecessor departments, with a contribution by British Gas.

Conjunctival Mycobacteriosis in Two Emus (Dromaius novaehollandiae)

Avian tuberculosis was diagnosed in two young adult female commercial emus ( Dromaius novaehollandiae) with granulomatous conjunctivitis. Histologically, the granulomas appeared typical of avian tuberculosis. Caseonecrotic cores were surrounded by a broad ring of palisading epithelioid macrophages and multinucleate giant cells with a moderate admixture of heterophils, lymphocytes, and plasma cells. One conjunctival granuloma had multifocal mineralization. At necropsy, granulomas were also found in visceral organs of both birds. Acid-fast bacilli were demonstrated in all lesions using Ziehl-Neelsen or Fite's stains. Culture confirmed the bacilli to be Mycobacterium avium (complex).