Mechanical Energy (mechanical + energy)

Distribution by Scientific Domains

Kinds of Mechanical Energy

  • specific mechanical energy

  • Selected Abstracts


    M. O. IWE
    Defatted soy flour and sweet potato flour containing 18% moisture were mixed in a pilot mixer, and extruded in an Almex-Bettenfeld single-screw extruder operated at varying rotational speed and die diameter. A central composite, rotatable nearly orthogonal design, which required 23 experiments for three factors (feed composition (fc), screw speed (ss) and die diameter (dd)) was developed and used for the generation of response surfaces. Effects of the extrusion variables on specific mechanical energy (SME), extrudate temperature (ET), and torque (T) were evaluated using response surface analysis. Results showed that product temperature increased with increases in die diameter, screw speed and feed composition. However, the effect of die diameter was greater than those of screw speed and feed composition. Decrease in die diameter with increase in sweet potato content increased torque. Screw speed exhibited a linear effect on torque. [source]

    A theory for elastic properties of single crystals with microstructure and its application to diffusion induced segregation

    T. Blesgen
    Abstract In this article a general theory for elastically stressed single crystals in the presence of microstructure is presented and an explicit formula for the resulting non-linear stored mechanical energy is obtained. The optimal microstructure under applied stress is characterised and the optimal laminates are identified in 2D. The analysis is based on a sharp lower estimate of the energy that relies on relaxation. The new theory is then used to extend existing models for diffusion induced segregation (DIS) in the case of (Zn,Fe)S single crystals. Numerical simulations based on finite elements are carried out and the results are compared with former computations of the homogeneous case. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Effect of extrusion parameters on flavour retention, functional and physical properties of mixtures of starch and d -limonene encapsulated in milk protein

    Sri Yuliani
    Summary The purpose of this research was to investigate the retention of flavour volatiles encapsulated in water-insoluble systems during high temperature,short time extrusion process. A protein precipitation method was used to produce water-insoluble capsules encapsulating limonene, and the capsules were added to the extruder feed material (cornstarch). A twin-screw extruder was used to evaluate the effect of capsule level of addition (0,5%), barrel temperature (125,145 °C) and screw speed (145,175 r.p.m.) on extruder parameters (torque, die pressure, specific mechanical energy, residence time distribution) and extrudate properties [flavour retention, texture, colour, density, expansion, water absorption index, water solubility index (WSI)]. Capsule level had a significant effect on extrusion conditions, flavour retention and extrudate physical properties. Flavour retention increased with the increase in capsule level from 0% to 2.5%, reached a maximum value at capsule level of 2.5% and decreased when the capsule level increased from 2.5% to 5%. The die pressure, torque, expansion ratio, hardness and WSI exhibited the opposite effect with the presence of capsules. [source]

    Plastic energy dissipation and its role on heating/melting of single-component polymers and multi-component polymer blends

    Bainian Qian
    Abstract Plastic energy dissipation (PED) of polymer particulates is, essentially, the energy dissipated during large and repeated plastic deformations of compacted polymer particulates while still in the solid state. PED is higher or much higher than VED, the viscous energy dissipation source of polymeric melts, because the stresses necessary to plastically deform viscoelastic polymer solids are orders of magnitude higher than the stresses needed to support viscous flow. In the last few years our group has demonstrated experimentally the dominant role which PED plays in the heating/melting of solid polymer (compacted) particulate beds in compounding processing equipment, such as twin-screw extruders and counterrotating continuous mixers/melters, in which the deformation of solid polymers is mandatory. We have also developed simple empirical methods of predicting the total axial distance needed for melting a given polymer in specific processing/compounding machines and processing. conditions, as well as the melting rates, all based on the mechanical energy dissipated during solid particulate compression. This work explores the more complex issue of how the PED behavior of single-component polymers may affect the PED (and the heating/melting) behavior of multi-component polymer blends. © 2003 Wiley Periodicals, Inc. Adv Polym Techn 22: 85,95, 2003; Published online in Wiley InterScience ( DOI 10.1002/adv.10039 [source]


    M. O. IWE
    Defatted soy flour and sweet potato flour containing 18% moisture were mixed in a pilot mixer, and extruded in an Almex-Bettenfeld single-screw extruder operated at varying rotational speed and die diameter. A central composite, rotatable nearly orthogonal design, which required 23 experiments for three factors (feed composition (fc), screw speed (ss) and die diameter (dd)) was developed and used for the generation of response surfaces. Effects of the extrusion variables on specific mechanical energy (SME), extrudate temperature (ET), and torque (T) were evaluated using response surface analysis. Results showed that product temperature increased with increases in die diameter, screw speed and feed composition. However, the effect of die diameter was greater than those of screw speed and feed composition. Decrease in die diameter with increase in sweet potato content increased torque. Screw speed exhibited a linear effect on torque. [source]


    To simulate commercial processing, a pilot scale 10-gallon (0.04m3), dual ribbon blender was equipped with a thermal control system and a 0.75 hp (559.27 W) electrical motor. An experimental design consisted of three temperatures (75, 80, 85C), three mixing rates (50, 100,150 RPM), and six durations (1, 5, 10, 15, 25, 35 min). Quantified process variables included: process strain and thermal history, and total, instantaneous, and change in mechanical energy. The Schreiber melt test was used to examine the relationship between the processing parameters and melt performance. A statistical analysis revealed significant parameter estimates (P < 0.0001) for each quantified variable in a general linear model. The process cheese industry will gain insight into controlled manufacturing conditions to deliver desired melt functionality. [source]

    Evaluating Energy Consumption and Efficiency of a Twin-Screw Extruder

    M. Liang
    ABSTRACT: Using the results from twin-screw extrusion of corn meal, both energy consumption and extruder efficiency were found to be significantly correlated with screw speed and specific feeding load (SFL). An increase in the SFL decreased the total specific mechanical energy, but increased the extruder efficiency. SFL influenced the extruder efficiency more than the screw speed. Increasing the screw speed from 300 to 450 rpm at a constant SFL level increased the extruder efficiency by 6 to 11%, whereas an increase of SFL from 0.0026 to 0.0038 kg rev 1 raised the extruder efficiency by 30%. Of the mechanical energy consumed per unit mass of extrudate, over 98% were used for shearing or viscous dissipation and less than 1.5% were for pumping during twin-screw extrusion of corn meal. [source]

    Informatic calibration of a materials properties database for predictive assessment of mechanically activated disordering potential for small molecule organic solids

    Yannan Lin
    Abstract The potential for small molecule organic crystalline materials to become disordered as a result of high shear mechanical processing was investigated. A data-driven model was generated from a database of critical materials properties, which were expected to correlate with the potential of a small molecule organic crystalline solid to become fully disordered by the application of mechanical energy. The model was compared with a previously published disordering model based on fundamental thermodynamic relationships. Samples of 23 crystalline solids were subjected to extensive comminution under controlled temperature conditions; powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) were used to confirm disordering. Logistic regression was used to investigate the significance of each materials property with respect to the prediction of disordering potential. Seven materials properties (glass transition temperature, melting temperature, heat of fusion, crystallographic density, Young's modulus, molar volume and attachment energy) were identified as having a significant correlation with the potential for material disordering. Stepwise multivariate logistic regression was used to further assess the correlation between disordering potential and each of the seven properties. A linear probability model based on two materials properties (glass transition temperature and molar volume) was developed for the prediction of disordering potential. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 98:2696,2708, 2009 [source]

    Development of a bulgur-like product using extrusion cooking

    Hamit Köksel
    Abstract In this study we (1) developed a new bulgur-like foodstuff using a durum wheat cultivar and an extrusion technique, (2) investigated the physicochemical properties of the extrudates produced and (3) sensorially evaluated the end-product after cooking. Durum wheat was processed in a laboratory-scale co-rotating twin-screw extruder with different levels of moisture content of the feed (367, 417 and 455,g,kg,1), screw speed (150 and 200,rpm) and feed rate (2.4 and 2.9,kg,h,1) to develop the bulgur-like product. The effects of extrusion conditions on system variables (die pressure and specific mechanical energy (SME)), physical properties (die swell and bulk density), pasting properties (peak, trough and final viscosities) and cooking and sensory properties of the bulgur-like products were determined. The results indicated that increased feed moisture content resulted in significant decreases in the die pressure and SME values of the extruded durum wheat products. As the moisture content and screw speed increased, the changes in die swell values were not significant. The lowest die swell and highest bulk density values were obtained at the highest feed moisture content. The extrusion variables also affected the pasting properties of the extrudates. Significant increases in each of the pasting properties occurred when the moisture content of the feed was increased. Some of the sensory properties (bulkiness, firmness, stickiness and taste,aroma) improved significantly as the feed moisture content increased, indicating better quality. Increased feed moisture content significantly improved cooking quality as determined by a decrease in colorimetric test results. Extrusion seems to be promising for the production of dry, relatively inexpensive bulgur-like products with acceptable sensory properties. © 2003 Society of Chemical Industry [source]

    Effect of the addition of calcium hydroxide on some characteristics of extruded products from blue maize (Zea mays L) using response surface methodology

    José J Zazueta-Morales
    Abstract The aim of this research was to study the effects of calcium hydroxide (0,0.2%) and screw speed (100,180,rpm) on the expansion index (EI), bulk density (BD), penetration force (PF) and specific mechanical energy (SME) values of blue maize meal extrudates. Blue maize meal was extruded using a commercial extruder (Brabender 20DN/8-235-00) with a compression screw ratio of 3:1. A second-order, central composite experimental design was used. It was found that the EI and SME values decreased and the BD and PF values increased when the calcium hydroxide concentration was increased. The screw speed had a significant effect only on the SME and PF values. Quadratic model fitness was shown for all responses, with values of R2,>,0.74, p of F (model) <0.01 and variability coefficient <13.3% (except for PF, 29.18%), and for almost all cases there was no lack of fit (p,>,0.055). Calcium hydroxide concentration showed good correlation (p,<,0.01) with EI (r,,=,,0.81), PF (r,,=,0.60), SME (r,,=,,0.76) and BD (r,,=,0.83). However, screw speed was marginally or not correlated (r,<,0.36, p,>,0.14) with the responses. The results suggest that it is possible to produce appropriate extruded products from blue maize fortified with calcium in an optimised calcium hydroxide concentration and screw speed range of 0.02,0.078% and 117,180,rpm respectively. © 2001 Society of Chemical Industry [source]

    A census of the Carina Nebula , II.

    Energy budget, global properties of the nebulosity
    ABSTRACT The first paper in this series took a direct census of energy input from the known OB stars in the Carina Nebula, and in this paper we study the global properties of the surrounding nebulosity. This detailed comparison may prove useful for interpreting observations of extragalactic giant H ii regions and ultraluminous infrared (IR) galaxies. We find that the total IR luminosity of Carina is about 1.2 × 107 L,, accounting for only about 50,60 per cent of the known stellar luminosity from Paper I. Similarly, the ionizing photon luminosity derived from the integrated radio continuum is about 7 × 1050 s,1, accounting for ,75 per cent of the expected Lyman continuum from known OB stars. The total kinetic energy of the nebula is about 8 × 1051 erg, or ,30 per cent of the mechanical energy from stellar winds over the lifetime of the nebula, so there is no need to invoke a supernova (SN) explosion based on energetics. Warm dust grains residing in the H ii region interior dominate emission at 10,30 ,m, but cooler grains at 30,40 K dominate the IR luminosity and indicate a likely gas mass of ,106 M,. We find an excellent correlation between the radio continuum and 20,25 ,m emission, consistent with the idea that the ,80-K grain population is heated by trapped Ly, photons. Similarly, we find a near perfect correlation between the far-IR optical depth map of cool grains and 8.6-,m hydrocarbon emission, indicating that most of the nebular mass resides as atomic gas in photodissociation regions and not in dense molecular clouds. Synchronized star formation around the periphery of Carina provides a strong case that star formation here was indeed triggered by stellar winds and ultraviolet radiation. This second generation appears to involve a cascade toward preferentially intermediate- and low-mass stars, but this may soon change when , Carinae and its siblings explode. If the current reservoir of atomic and molecular gas can be tapped at that time, massive star formation may be rejuvenated around the periphery of Carina much as if it were a young version of Gould's Belt. Furthermore, when these multiple SNe occur, the triggered second generation will be pelted repeatedly with SN ejecta bearing short-lived radioactive nuclides. Carina may therefore represent the most observable analogue to the cradle of our own Solar system. [source]

    Using a New Interfacial Area Transport Equation to Predict Interfacial Area in Co-current Jet Mixers

    Stephen L. Yarbro
    Abstract In multiphase operations, such as liquid-liquid or gas-liquid systems, the interfacial area affects the interfluid heat, mass and momentum transfer and ultimately, the overall equipment performance. To better understand the mixing process, we developed a multi-fluid model that predicts interfacial area for kerosene-water mixtures in co-current jet mixers. The model has ensemble-averaged conservation equations for each fluid and includes a transport equation, derived from an overall energy balance, for the interfacial area concentration. In the model, the mechanical energy of the continuous phase creates interfacial area. Comparing the final, one-dimensional model to experimental data proved the model is accurate. Over 93% of the calculated and experimental data obtained from 0.027 inch and 0.041 inch diameter co-current jet mixers compared within 15%. Dans les opérations polyphasiques, comme les systèmes liquide-liquide ou gaz-liquide, la surface interfaciale influe sur les transferts inter-fluides de chaleur, de matière et de quantité de mouvement et donc sur la performance globale des équipements. Pour mieux comprendre le procédé de mélange, nous avons mis au point un modèle multifluide qui prédit la surface interfaciale pour des mélanges kérosène-eau dans des mélangeurs cocourants à jets. Le modèle comprend des équations de conservation globalement moyennées pour chaque fluide ainsi qu'une équation de transport, établie à partir d'un bilan énergétique global, pour la concentration de la surface interfaciale. Dans ce modèle, l'énergie mécanique de la phase continue crée la surface interfaciale. La comparaison entre le modèle unidimensionnel final et les données expérimentales démontre la bonne précision du modèle. Plus de 93 % des données calculées et expérimentales obtenues pour des mélangeurs cocourants à jets de 0,027 à 0,041 pouces de diamètre sont comparables à 15 % près. [source]

    Is the efficiency of mammalian (mouse) skeletal muscle temperature dependent?

    C. J. Barclay
    Myosin crossbridges in muscle convert chemical energy into mechanical energy. Reported values for crossbridge efficiency in human muscles are high compared to values measured in vitro using muscles of other mammalian species. Most in vitro muscle experiments have been performed at temperatures lower than mammalian physiological temperature, raising the possibility that human efficiency values are higher than those of isolated preparations because efficiency is temperature dependent. The aim of this study was to determine the effect of temperature on the efficiency of isolated mammalian (mouse) muscle. Measurements were made of the power output and heat production of bundles of muscle fibres from the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles during isovelocity shortening. Mechanical efficiency was defined as the ratio of power output to rate of enthalpy output, where rate of enthalpy output was the sum of the power output and rate of heat output. Experiments were performed at 20, 25 and 30°C. Maximum efficiency of EDL muscles was independent of temperature; the highest value was 0.31 ± 0.01 (n= 5) at 30°C. Maximum efficiency of soleus preparations was slightly but significantly higher at 25 and 30°C than at 20°C; the maximum mean value was 0.48 ± 0.02 (n= 7) at 25°C. It was concluded that maximum mechanical efficiency of isolated mouse muscle was little affected by temperature between 20 and 30°C and that it is unlikely that differences in temperature account for the relatively high efficiency of human muscle in vivo compared to isolated mammalian muscles. [source]

    Fluctuation dynamo based on magnetic reconnections

    A.W. Baggaley
    Abstract We develop a new model of the fluctuation dynamo in which the magnetic field is confined to thin flux ropes advected by a multi-scale flow which models turbulence. Magnetic dissipation occurs only via reconnections of flux ropes. The model is particularly suitable for rarefied plasma, such as the solar corona or galactic halos. We investigate the kinetic energy release into heat, mediated by dynamo action, both in our model and by solving the induction equation with the same flow. We find that the flux rope dynamo is more than an order of magnitude more efficient at converting mechanical energy into heat. The probability density of the magnetic energy released during reconnections has a power-law form with the slope ,3, consistent with the solar corona heating by nanoflares. We also present a nonlinear extension of the model. This shows that a plausible saturation mechanism of the fluctuation dynamo is the suppression of turbulent magnetic diffusivity, due to suppression of random stretching at the location of the flux ropes. We confirm that the probability distribution function of the magnetic line curvature has a power-law form suggested by Schekochihin et al. (2002c). We argue, however, using our results that this does not imply a persistent folded structure of magnetic field, at least in the nonlinear stage (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Effects of local thermodynamics and of stellar mass ratio on accretion disc stability in close binaries

    G. Lanzafame
    Abstract Inflow kinematics at the inner Lagrangian point L1, gas compressibility, and physical turbulent viscosity play a fundamental role on accretion disc dynamics and structure in a close binary (CB). Physical viscosity supports the accretion disc development inside the primary gravitational potential well, developing the gas radial transport, converting mechanical energy into heat. The Stellar-Mass-Ratio (SMR) between the compact primary and the secondary star (M1/M2) is also effective, not only in the location of the inner Lagrangian point, but also in the angular kinematics of the mass transfer and in the geometry ofthe gravitational potential wells. In this work we pay attention in particular to the role ofthe SMR, evaluating boundaries, separating theoretical domains in compressibility-viscosity graphs where physical conditions allow a well-bound disc development, as a function ofmass transfer kinematic conditions. In such domains, the lower is the gas compressibility (the higher the polytropic index ,), the higher is the physical viscosity (,) requested. In this work, we show how the boundaries of such domains vary as a function of M1/M2. Conclusions as far as dwarf novae outbursts are concerned, induced by mass transfer rate variations, are also reported. The smaller M1/M2, the shorter the duration of the active-to-quiet and vice-versa transitional phases. Time-scales are of the order of outburst duration of SU Uma, OY Car, Z Cha and SS Cyg-like objects. Moreover, conclusions as far as active-quiet-active phenomena in a CB, according to viscous-thermal instabilities, in accordance to such domains, are also reported (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Energy scavenging for energy efficiency in networks and applications

    Kyoung Joon Kim
    Telecommunication networks will play a huge part in enabling eco-sustainability of human activity; one of the first steps towards this is to dramatically increase network energy efficiency. In this paper we present two novel approaches for energy scavenging in networks. One involves thermal energy scavenging for improving wireless base station energy efficiency, and the other involves mechanical energy scavenging for powering sensors in sensor networks, for machine-to-machine (M2M) communications, and for smart grid applications. Power amplifier (PA) transistors in base stations waste 30 percent of the total energy used in a wireless access network (WAN) as heat to the environment. We propose a thermoelectric energy recovery module (TERM) to recover electricity from the waste heat of PA transistors. A fully coupled thermoelectric (TE) model, combining thermoelectricity and heat transfer physics, is developed to explore the power generation performance and efficiency as well as the thermal performance of the TERM. The TE model is comprehensively used to determine optimized pellet geometries for power generation and efficiency as a function of PA transistor heat dissipation, heat sink performance, and load resistance. Maximum power generation and efficiency for various parametric conditions are also explored. Untapped kinetic energy is almost everywhere in the form of vibrations. This energy can be converted into electrical energy by means of transducers to power wireless sensors and mobile electronics in the range of microwatts to a few milliwatts. However, many problems limit the efficiency of current harvesting generators: narrow bandwidth, low power density, micro-electro-mechanical system (MEMS) scaling, and inconsistency of vibrating sources. We explore energy scavenger designs based on multiple-mass systems to increase harvesting efficiency. A theoretical and experimental study of two degrees-of-freedom (2-DOF) vibration-powered generators is presented. Both electromagnetic and piezoelectric conversion methods are modeled by using a general approach. Experimental results for the multi-resonant system are in agreement with the analytical predictions and demonstrate significantly better performance in terms of maximum power density per total mass and a wider bandwidth compared to single DOF (1-DOF) generators. © 2010 Alcatel-Lucent. [source]

    Nanorobots: The Ultimate Wireless Self-Propelled Sensing and Actuating Devices

    Samuel Sánchez Dr.
    Abstract Natural motor proteins, "bionanorobots," have inspired researchers to develop artificial nanomachines (nanorobots) able to move autonomously by the conversion of chemical to mechanical energy. Such artificial nanorobots are self-propelled by the electrochemical decomposition of the fuel (up to now, hydrogen peroxide). Several approaches have been developed to provide nanorobots with some functionality, such as for controlling their movement, increasing their power output, or transporting different cargo. In this Focus Review we will discuss the recent advances in nanorobots based on metallic nanowires, which can sense, deliver, and actuate in complex environments, looking towards real applications in the not-too-distant future. Los motores naturales basados en proteínas "bionanorobots" han inspirado a investigadores a desarrollar nano-máquinas capaces de moverse de forma autónoma gracias a la conversión de energía química en mecánica. Los nanorobots artificiales se auto-propulsan por la descomposición electroquímica del combustible (hasta la fecha, peróxido de hidrogeno). Se han desarrollado varias propuestas para modificar estos nanorobots con la finalidad de controlar su movimiento, aumentar la potencia o transportar diferentes cargos. En esta revisión discutiremos los recientes avances en nanorobots artificiales basados en nano-hilos metálicos con perspectivas a aplicaciones en un futuro cercano. Estos nanorobots pueden sentir, liberar y actuar en medios complejos. [source]