A study of optimum cowl shapes and flow port locations for minimum drag with effective engine cooling, volume 2

The listings, user's instructions, sample inputs, and sample outputs of two computer programs which are especially useful in obtaining an approximate solution of the viscous flow over an arbitrary nonlifting three dimensional body are provided. The first program performs a potential flow solution by a well known panel method and readjusts this initial solution to account for the effects of the boundary layer displacement thickness, a nonuniform but unidirectional onset flow field, and the presence of air intakes and exhausts. The second program is effectually a geometry package which allows the user to change or refine the shape of a body to satisfy particular needs without a significant amount of human intervention. An effort to reduce the cruise drag of light aircraft through an analytical study of the contributions to the drag arising from the engine cowl shape and the foward fuselage area and also that resulting from the cooling air mass flowing through intake and exhaust sites on the nacelle is presented. The programs may be effectively used to determine the appropriate body modifications or flow port locations to reduce the cruise drag as well as to provide sufficient air flow for cooling the engine

Automated design of minimum drag light aircraft fuselages and nacelles

The constrained minimization algorithm of Vanderplaats is applied to the problem of designing minimum drag faired bodies such as fuselages and nacelles. Body drag is computed by a variation of the Hess-Smith code. This variation includes a boundary layer computation. The encased payload provides arbitrary geometric constraints, specified a priori by the designer, below which the fairing cannot shrink. The optimization may include engine cooling air flows entering and exhausting through specific port locations on the body

Flight test evaluation of predicted light aircraft drag, performance, and stability

A technique was developed which permits simultaneous extraction of complete lift, drag, and thrust power curves from time histories of a single aircraft maneuver such as a pull up (from V max to V stall) and pushover (to V max for level flight). The technique, which is an extension of nonlinear equations of motion of the parameter identification methods of Iliff and Taylor and includes provisions for internal data compatibility improvement as well, was shown to be capable of correcting random errors in the most sensitive data channel and yielding highly accurate results. Flow charts, listings, sample inputs and outputs for the relevant routines are provided as appendices. This technique was applied to flight data taken on the ATLIT aircraft. Lack of adequate knowledge of the correct full throttle thrust horsepower true airspeed variation and considerable internal data inconsistency made it impossible to apply the trajectory matching features of the technique

Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals

Crystals of SrMn 2 Sb 2 and BaMn 2 Sb 2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ , heat capacity C p , and magnetic susceptibility χ measurements versus temperature T , and magnetization versus field M ( H ) isotherm measurements. SrMn 2 Sb 2 adopts the trigonal CaAl 2 Si 2 -type structure, whereas BaMn 2 Sb 2 crystallizes in the tetragonal ThCr 2 Si 2 -type structure. The ρ ( T ) data indicate semiconducting behaviors for both compounds with activation energies of ≳ 0.35 eV for SrMn 2 Sb 2 and 0.16 eV for BaMn 2 Sb 2 . The χ ( T ) and C p ( T ) data reveal antiferromagnetic (AFM) ordering at T N = 110 K for SrMn 2 Sb 2 and 450 K for BaMn 2 Sb 2 . The anisotropic χ ( T ≤ T N ) data also show that the ordered moments in SrMn 2 Sb 2 are aligned in the hexagonal a b plane, whereas the ordered moments in BaMn 2 Sb 2 are aligned collinearly along the tetragonal c axis. The a b -plane M ( H ) data for SrMn 2 Sb 2 exhibit a continuous metamagnetic transition at low fields 0 \u3c H ≲ 1 T, whereas BaMn 2 Sb 2 exhibits no metamagnetic transitions up to 5.5 T. The χ ( T ) and C p ( T ) data for both SrMn 2 Sb 2 and BaMn 2 Sb 2 indicate strong dynamic short-range AFM correlations above their respective T N up to at least 900 K within a local-moment picture, corresponding to quasi-two-dimensional magnetic behavior. The present results and a survey of the literature for Mn pnictides with the CaAl 2 Si 2 and ThCr 2 Si 2 crystal structures show that the T N values for the CaAl 2 Si 2 -type compounds are much smaller than those for the ThCr 2 Si 2 -type materials

Primjena visokotemperaturne DTA za mikrolegirane čelike

Paper deals with investigation of phase transitions temperatures for selected real grades of micro-alloyed steels. Temperatures of characteristic phase transitions were obtained using Setaram SETSYS 18TM. The DTA technique was selected for the study of micro-alloyed steels. Temperatures of phase transitions (liquidus, solidus etc.) were obtained. Influence of admixed and alloyed elements on shift of temperatures was investigated. Resulting data were compared with temperatures of phase transitions of Fe-C, Fe-Mn systems and with temperatures calculated according to relations published in available literature. Thermodynamic-kinetic solidification model IDS was used to calculate characteristic equilibrium temperatures of investigated systems.Članak se bavi studijom faznih transformacija odabranih mikrolegiranih čelika. Temperaturne karakteristike faznih transformacija su istraživane rabljenjem laboratorijskog sustava Setaram SETSYS-18TM. DTA tehnika je odabrana za studij mikrolegiranih čelika. Temperature faznih transformacija (likvidus, solidus itd.) su dobivene. Istraživan je utjecaj primjesa i legirajućih elemenata na promjene temperatura faznih transformacija. Dobiveni experimentalni rezultati su bili uspoređeni s temperaturama faznih transformacija sistema Fe-C, Fe-Mn a i s temperaturama izračunatih iz dostupne literature. Termodinamičkokinetički model skrućivanja IDS je rabljen za izračun karakterističnih ravnotežnih temperatura faznih transformacija istraživanih sustava

Comparison of measured and calculated thermophysical properties of nickel super-alloys

Three real grades of nickel super-alloys (IN 713LC, IN 738LC and IN 792-5A) were investigated and values of temperatures of phase transformations and latent heats of melting were obtained. All investigated quantities are very important for thermodynamic and kinetic modelling. Moreover, these data are also valuable for a lot of software used for technological processes modelling. Experimental values were obtained using Differential Thermal Analysis (DTA) measurements. Calculations were performed using Thermo-Calc 3.1 software with the use of three different databases (SSOL5, TTNI8 and TCNI6). Comparison and discussion of experimental and calculated data was performed

Pharmacologic Treatment for Pediatric Gastroparesis: A Review of the Literature

There have been a number of agents that have been tried for treatment of gastroparesis over the past 3 decades, with varying levels of success. Guidelines exist for the management of gastroparesis in adults; however, even though the cause of gastroparesis in children is similar to that in adults, no guidelines exist for treating pediatric gastroparesis as studies on the topic are limited. With what little information we have on pediatric gastroparesis, medications used in children's studies do not seem to demonstrate the same results as in adult patients with gastroparesis; thus, future studies of whether certain medications are effective for treating pediatric gastroparesis and at what dose still need to be conducted. Pharmacological treatment options for pediatric gastroparesis do not show a clear correlation of resolving or even maintaining gastroparesis-associated symptoms or disease state. This article reviews the available studies of drugs that have shown some efficacy, with an emphasis on pediatric studies

Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair

Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multi-functionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-beta 1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum. Copyright (C) 2011 S. Karger AG, Base

Termofizikalna i strukturalna studija IN 792-5A niklove superlegure

The presented paper deals with study of phase transformations temperatures of nickel based superalloy IN 792-5A with application of DTA – method and use of experimental laboratory system for simultaneous thermal analysis SETARAM Setsys 18TM. Samples taken from as-received state of superalloy were heated with controlled ramp rates (1, 5, 10 and 20 °C•min-1) and immediately after melting they were cooled with the same controlled ramp rate. The samples before and after DTA-analysis were also subjected to the phase analysis with use of scanning electron microscopy on the microprobe (JCXA 733) equipped with energy dispersive analyser EDAX (EDAM 3).Rad daje studiju temperature faznih transformacija niklove superslitine IN792-5A primjenom DTA metode te eksperimentalnog laboratorijskog sustava za simulaciju termalne analize SETARAM Setsys 18TM. Uzorci su uzeti iz početnog stanja legure i održavani definiranim brzinama (1, 5, 10 i 20 °C•min-1) i poslije ohlađeni kontroliranim brzinama. Uzorci su prije i poslije DTA analiza bili predmet fazne analize s primjenom skeninga elektronske mikroskopije (JCXA 733) dopunjeno s energi disperznom analizom EDAX (EDAM 3)