1,859 research outputs found

    AN APPLICATION OF THE PHOSPHORUS CONSISTENT RULE FOR ENVIRONMENTALLY ACCEPTABLE COST-EFFICIENT MANAGEMENT OF BROILER LITTER IN CROP PRODUCTION

    Get PDF
    We calculated the profitability of using broiler litter as a source of plant nutrients using the phosphorus consistent litter application rule. The cost saving by using litter is 37% over the use of chemical fertilizer alone to meet the nutrient needs of major crops grown in Alabama. In the optimal solution, only a few routes of all the possible routes developed were used for inter- and intra- county litter hauling. If litter is not adopted as the sole source of crop nutrients, the best environmental policy may be to pair the phosphorus consistent rule with taxes, marketable permits, and subsidies.Environmental Economics and Policy, Production Economics,

    Dynamical Evolution of Globular Clusters in Hierarchical Cosmology

    Get PDF
    We probe the evolution of globular clusters that could form in giant molecular clouds within high-redshift galaxies. Numerical simulations demonstrate that the large and dense enough gas clouds assemble naturally in current hierarchical models of galaxy formation. These clouds are enriched with heavy elements from earlier stars and could produce star clusters in a similar way to nearby molecular clouds. The masses and sizes of the model clusters are in excellent agreement with the observations of young massive clusters. Do these model clusters evolve into globular clusters that we see in our and external galaxies? In order to study their dynamical evolution, we calculate the orbits of model clusters using the outputs of the cosmological simulation of a Milky Way-sized galaxy. We find that at present the orbits are isotropic in the inner 50 kpc of the Galaxy and preferentially radial at larger distances. All clusters located outside 10 kpc from the center formed in the now-disrupted satellite galaxies. The spatial distribution of model clusters is spheroidal, with a power-law density profile consistent with observations. The combination of two-body scattering, tidal shocks, and stellar evolution results in the evolution of the cluster mass function from an initial power law to the observed log-normal distribution.Comment: 5 pages, proceedings of IAU 246 "Dynamical Evolution of Dense Stellar Systems", eds. Vesperini, Giersz, Sill

    Modeling the dynamical evolution of the M87 globular cluster system

    Full text link
    We study the dynamical evolution of the M87 globular cluster system (GCS) with a number of numerical simulations. We explore a range of different initial conditions for the GCS mass function (GCMF), for the GCS spatial distribution and for the GCS velocity distribution. We confirm that an initial power-law GCMF like that observed in young cluster systems can be readily transformed through dynamical processes into a bell-shaped GCMF. However,only models with initial velocity distributions characterized by a strong radial anisotropy increasing with the galactocentric distance are able to reproduce the observed constancy of the GCMF at all radii.We show that such strongly radial orbital distributions are inconsistent with the observed kinematics of the M87 GCS. The evolution of models with a bell-shaped GCMF with a turnover similar to that currently observed in old GCS is also investigated. We show that models with this initial GCMF can satisfy all the observational constraints currently available on the GCS spatial distribution,the GCS velocity distribution and on the GCMF properties.In particular these models successfully reproduce both the lack of a radial gradient of the GCS mean mass recently found in an analysis of HST images of M87 at multiple locations, and the observed kinematics of the M87 GCS.Our simulations also show that evolutionary processes significantly affect the initial GCS properties by leading to the disruption of many clusters and changing the masses of those which survive.The preferential disruption of inner clusters flattens the initial GCS number density profile and it can explain the rising specific frequency with radius; we show that the inner flattening observed in the M87 GCS spatial distribution can be the result of the effects of dynamical evolution on an initially steep density profile. (abridged)Comment: 15 pages,14 figures;accepted for publication in The Astrophysical Journa

    Dynamic Gaits and Control in Flexible Body Quadruped Robot

    Get PDF
    Legged robots are highly attractive for military purposes such as carrying heavy loads on uneven terrain for long durations because of the higher mobility they give on rough terrain compared to wheeled vehicles/robots. Existing state-of-the-art quadruped robots developed by Boston Dynamics such as LittleDog and BigDog do not have flexible bodies. It can be easily seen that the agility of quadruped animals such as dogs, cats, and deer etc. depend to a large extent on their ability to flex their bodies. However, simulation study on step climbing in 3D terrain quadruped robot locomotion with flexible body has not been reported in literature. This paper aims to study the effect of body flexibility on stability and energy efficiency in walking mode, trot mode and running (bounding) mode on step climbing

    Merging of globular clusters within inner galactic regions. I. Do they survive the tidal interaction?

    Full text link
    The main topic of this paper is the investigation of the modes of interaction of globular clusters (GCs) moving in the inner part of a galaxy. This is tackled by means of high-resolution N-body simulations, whose first results are presented in this article. Our simulations dealt with primordial very massive (order of 10^7 solar masses) GCs that were able to decay, because of dynamical friction, into the inner regions of triaxial galaxies on a time much shorter than their internal relaxation time. To check the disruptive role of both tidal forces and GC-GC collisions, we maximised the tidal interaction considering GCs on quasi-radial orbits. The available CPU resources allowed us to follow 8 oscillations of the GCs along their orbits and the main findings are: i) clusters with an initial high enough King concentration parameter (c>=1.2), preserve up to 50% of their initial mass; ii) the inner density distribution of the survived clusters keep a King model profile; iii) GC-GC collisions have a negligible effect with respect to that caused by the passage through the galactic center; iv) the orbital energy dissipation due to the tidal interaction is of the same order of that caused by dynamical friction; v) complex sub-structures like "ripples" and "clumps" formed, as observed around real clusters. These findings support the validity of the hypothesis of merging of GCs in the galactic central region, with modes that deserve further careful investigations.Comment: LaTeX 2e, AASTeX v5.x, 23 pages with 14 figures. Accepted for publication on the Astrophysical Journal. Final version with major change

    Molecular and thermal studies of carbon fiber precursor polymers with low thermal-oxidative stabilization characteristics

    Get PDF
    In this investigation, terpolymers, copolymers, and homopolymer of acrylonitrile with dimethylaminopropyl acrylamide (DMAPA), itaconic acid (IA) viz., poly(acrylonitrile‐ran‐3‐dimethylaminopropyl acrylamide‐ran‐itaconic acid) [P(AN‐DMAPP‐IA)], poly(acrylonitrile‐co‐3, dimethylaminopropyl acrylamide) [P(AN‐DMAPP)] were synthesized with varying amounts of comonomers using solution polymerization process. The chemical structure, composition, bonding network were determined employing infrared, 1H and, 13‐carbon nuclear magnetic resonance spectroscopic techniques. Molecular characteristics of as‐synthesized polymers such as different kinds of average molecular weights, molecular weight distribution were estimated applying solution viscometry and size exclusion chromatography. The influence of comonomers (DMPAA, IA) on the thermal stabilization characteristics of acrylonitrile terpolymers in comparison with copolymers and homopolymers of acrylonitrile were studied using differential scanning calorimetry (DSC), hyphenated thermal techniques (thermal gravimetry coupled with differential thermal analyzer).The DSC curves of P(AN‐DMAPP‐IA) exhibit a distinct broader bimodal peaks with thermal exotherm initiating at as low as 165 °C, and followed by two peaks with temperature difference of 42 °C, releasing the evolved heat at a release rate of 0.7–0.11 J g−1s−1over 10 min as compared to 1.2, 7.5 J g−1s−1 in 4.5, 2 min as observed in P(AN‐DMAPP), polyacrylonitrile, respectively. The thermal stability of P(AN‐DMAPP‐IA) and P(AN‐DMAPP), as evidenced by TGA‐DTA was found to be higher than PAN homopolymers. Specific heat capacity measurements confirmed the DSC results. Bulk densities of P(AN‐DMAPP‐IA) were in the range 0.31–0.35 g/cc. These results confirm the low‐temperature stabilization characteristics and suitability of P(AN‐DMAPP‐IA) as low cost carbon fiber precursor polymer

    A large fibroma polyp of labia majora

    Get PDF
    Fibroepithelial stromal polyps are benign proliferations which are usually polypoid or pedunculated, and less than 5cm in size. They are generally single lesions but can be multiple during pregnancy. They can be polypoid or pedunculated and are usually solitary. Symptoms usually include bleeding, discharge and general discomfort with sensation of a mass. They typically have a central fibrovascular core and contain stellate and multinucleated stromal cells which are best seen beneath the surface epithelium. True myxoid stroma is absent. Although vulvovaginal fibroepithelial stromal polyps are well documented, a giant variant such as the one authors report here is rather rare. To the knowledge, present case is the largest fibroepithelial stromal polyp compared to others reported in the literature

    Performance Analysis of Process Parameters on Machining Titanium (Ti-6Al-4V) Alloy Using Abrasive Water Jet Machining Process

    Get PDF
    AbstractOwing to its light weight and corrosive resistant, Titanium (Ti-6Al-4V) alloy is mainly utilized in fabricating medical device applications. Since it has high strength, it is very difficult to machine alloy using conventional machining. In the present study, an endeavor has been made to machine titanium alloy using AWJM process. Since the process involves with less heat affect zone and higher material removal, it is possible to enhance machinability of workpiece. It has attempted to find the influence of process parameters on surface roughness and topography for enhancing the process. It has been observed that the abrasive flow rate and standoff distance has the most significant role on determining surface quality

    Novel method to manage weeds in the rainfed groundnut (var. VRI 8 and TMV 14) using nano encapsulated herbicide formulations

    Get PDF
    The groundnut crop harbours heavy weed infestation due to its small stature and slow growing nature. The current weed management practices of hand weeding and use of commercial herbicides are unsuitable because of high labour cost and inadequate moisture availability to activate herbicides.  In order to release the herbicide in a smart way, this experiment aimed to study the efficacy of encapsulated herbicides . Field experiments were conducted during Kharif 2021 and late Rabi 2022 under rainfed conditions in randomised block design with three replications. The treatments consisted of sulfentrazone, oxyfluorfen, diclosulam and metolachlor in both commercial and encapsulated form using two doses, hand weeding at 20 and 40 DAS, weed free plot and weedy check. Minimum weed density (28.33 and 17.30 No./m2 at 90 DAS during Kharif and late Rabi respectively) and weed dry weight (65.33 and 61.25 g/m2 at 90 DAS during Kharif and late Rabi respectively) were observed in hand weeding at 20 and 40 DAS (T19) followed by diclosulam @ 25 g ha-1 with encapsulation (T7). Maximum weed density and weed dry weight was observed in metolachlor @ 1 kg/ha with encapsulation (T8). Higher productivity was observed in hand weeding at 20 and 40 DAS (T19) (1802 kg ha-1  and 1753 kg ha-1  pod yield during Kharif and late Rabi respectively) and higher profitability was obtained in diclosulam @ 25 g ha-1 with encapsulation (T7) (1.80 and 2.01 B:C ratio during (Kharif and late Rabi respectively). Nano-encapsulated herbicides can thus significantly improve weed control in rainfed groundnut
    corecore