Three-dimensional laser Doppler anemometer measurements of a jet in a crossflow

A three-dimensional laser Doppler anemometer (3D-LDA) was used in a wind tunnel to measure a jet in a crossflow. Measurements were made in the vicinity of a 5-cm-diam jet which issued normally into a 10.65 m/sec wind tunnel crossflow; the velocity ratio Vjet/Vinf was 8. Detailed lateral surveys were made at two elevations (z = cm and 2 cm); both elevations were within the region affected by the boundary layer on the plate. The results are believed to provide reliable velocity field information in the boundary layer of the jet in a crossflow. Turbulence information also is available and believed to be roughly correct, although it may be subject to broadening effects for the lower values of turbulence. A weak vortex pair was observed in the wake at the plate surface. This structure existed in the boundary layer and built confidence because the 3D-LDA was, indeed, able to resolve fine detail in the wake. The capabilities of the 3D-LDA not only allow the making of the velocity surveys, but can be utilized to follow mean streamlines in the flow

Chemical compositions and plasma parameters of planetary nebulae with Wolf-Rayet and wels type central stars

Aims: Chemical compositions and other properties of planetary nebulae around central stars of spectral types [WC], [WO], and wels are compared with those of `normal' central stars, in order to clarify the evolutionary status of each type and their interrelation. Methods: We use plasma diagnostics to derive from optical spectra the plasma parameters and chemical compositions of 48 planetary nebulae. We also reanalyze the published spectra of a sample of 167 non-WR PN. The results as well as the observational data are compared in detail with those from other studies of the objects in common. Results: The central star's spectral type is clearly correlated with electron density, temperature and excitation class of the nebula, [WC] nebulae tend to be smaller than the other types. All this corroborates the view of an evolutionary sequence from cool [WC 11] central stars inside dense, low excitation nebulae towards hot [WO 1] stars with low density, high excitation nebulae. The wels PN, however, appear to be a separate class of objects, not linked to WRPN by evolution, --abridged--Comment: 17 pages, 28 figures, Accepted in A&A. Accepted in A&

PAH Formation in O-rich Planetary Nebulae

Polycyclic aromatic hydrocarbons (PAHs) have been observed in O-rich planetary nebulae towards the Galactic Bulge. This combination of oxygen-rich and carbon-rich material, known as dual-dust or mixed chemistry, is not expected to be seen around such objects. We recently proposed that PAHs could be formed from the photodissociation of CO in dense tori. In this work, using VISIR/VLT, we spatially resolved the emission of the PAH bands and ionised emission from the [SIV] line, confirming the presence of dense central tori in all the observed O-rich objects. Furthermore, we show that for most of the objects, PAHs are located at the outer edge of these dense/compact tori, while the ionised material is mostly present in the inner parts of these tori, consistent with our hypothesis for the formation of PAHs in these systems. The presence of a dense torus has been strongly associated with the action of a central binary star and, as such, the rich chemistry seen in these regions may also be related to the formation of exoplanets in post-common-envelope binary systems.Comment: 14, accepted for publication in the MNRAS Journa

Improvement of methods design-technological pre-production through the use of a through parameterization

УДК 004.9, БКК 74.58The paper suggests ways to improve the methodology of design and technological preparation of production based parameterization through its stages

Abundances of planetary nebulae in the Galactic bulge

Context. Planetary nebulae (PNe) abundances are poorly known for those nebulae in the Galactic bulge. This is because of the high and uneven extinction in the bulge which makes visual spectral measurements difficult. In addition, the extinction corrections may be unreliable. Elements considered are O, N, Ne, S, Ar, and Cl. Aims. We determine the abundances in 19 PNe, 18 of which are located in the bulge. This doubles the number of PNe abundance determinations in the bulge. The Galactic abundance gradient is discussed for five elements. Methods. The mid-infrared spectra measured by the Spitzer Space Telescope are used to determine the abundances. This part of the spectrum is little affected by extinction for which an uncertain correction is no longer necessary. In addition the connection with the visible and ultraviolet spectrum becomes simpler because hydrogen lines are observed both in the infrared and in the visible spectra. In this way we more than double the number of PNe with reliable abundances. Results. Reliable abundances are obtained for O, N, Ne, S, and Ar for Galactic bulge PNe. Conclusions. The Galactic abundance gradient is less steep than previously thought. This is especially true for oxygen. The sulfur abundance is reliable because all stages of ionization expected have been measured. It is not systematically low compared to oxygen as has been found for some Galactic PNe

Identificiranje relevantnih segmenata potencijalnih korisnika chatbota u bankarstvu na temelju ponašanja pri prihvaćanju tehnologije

Purpose – Chatbot technology is expected to revolutionize customer service in financial institutions. However, the adoption of customer service chatbots in banking remains low. Therefore, the aim of this paper is to identify relevant segments of potential banking chatbot users based on technology adoption behavior. Design/Methodology/Approach – Data for the research was collected through an online questionnaire in Romania using the non-probability sampling method. The 287 questionnaires were analyzed using hierarchical and k-means cluster analysis. Findings and implications – The analysis revealed three distinct segments: Innovators (26%), consisting of highly educated young women employed in the business sector; the Late Majority (55%), consisting of young women with higher education degrees who work in services-related fields; and Laggards (19%), consisting of educated middle-aged men employed in the business sector. New significant differences among demographic and banking behavior variables were observed across the profiles of potential banking chatbot user segments. Limitations – The study is based on a non-probability sample collected from only one country, with a rather small sample size. Originality – Technology acceptance variables (perceived usefulness, perceived ease of use), expanded to include constructs such as awareness of service, perceived privacy risk, and perceived compatibility, were found to be appropriate for customer segmentation purposes in the context of chatbot applications based on artificial intelligence. The study also revealed a new innovator demographic profile.Svrha – Očekuje se da će chatbot tehnologija revolucionirati usluge korisnicima u financijskim institucijama. Međutim prihvaćenost chatbota među korisnicima usluga banaka još je uvijek niska. Stoga je cilj ovog rada identificirati relevantne segmente potencijalnih korisnika bankovnih chatbotova na temelju ponašanja pri usvajanju tehnologije. Metodološki pristup – Podatci su prikupljeni u Rumunjskoj ne temelju neprobabilističke metode uzorkovanja putem online anketnog upitnika. Analizirano je 287 anketnih upitnika primjenom hijerarhijske i k-mean klasterske analize. Rezultati i implikacije – Analizom su otkrivena tri različita segmenta: Inovatori (26%) koji su visokoobrazovani, mlade žene zaposlene u području poslovne ekonomije; Kasna većina (55%) koju čine mlađe žene s višom stručnom spremom zaposlene u područjima povezanim s uslugama; Kolebljivci (19%) koji su obrazovani, muškarci srednjih godina zaposleni u području poslovne ekonomije. Otkrivene su nove značajne razlike među profilima segmenata potencijalnih korisnika chatbota u bankarstvu vezane uz demografske te varijable ponašanja korisnika usluga u bankarstvu. Ograničenja – Istraživanje se temelji na nepobabilističkom uzorku prikupljenom u samo jednoj zemlji, a veličina uzorka je prilično mala. Doprinos – Utvrđeno je da su varijable prihvaćanja tehnologije (percipirana korisnost, percipirana jednostavnost korištenja) proširene s konstruktima kao što su svjesnost o usluzi, percipirani rizik privatnosti i percipirana kompatibilnost, prikladne za potrebe segmentacije korisnika u kontekstu chatbot aplikacija temeljenih na umjetnoj inteligenciji. Istraživanje je otkrilo novi demografski profil inovatora

Microbial Foodborne Disease: Hospitalizations, Medical Costs and Potential Demand for Safer Food

Food Consumption/Nutrition/Food Safety, Health Economics and Policy,