Decrease In Energy Dissipation Research Articles

Energy efficient multilevel network model for heterogeneous WSNs

In this paper, we propose a multilevel heterogeneous network model that is characterized by two types of parameters: primary and secondary parameters. The primary parameter decides the level of heterogeneity and the secondary parameters are decided according to the level of heterogeneity. This model can describe a network in which the nodes can have up to nth level of energy (n is a finite number) depending upon the parameter values. We evaluate the performance of the HEED, a clustering protocol, using this model and name the resultant protocol as MLHEED (Multi Level HEED) protocol. For n level of heterogeneity, this protocol is denoted by MLHEED-n. The numbers of nodes of each type in any level of heterogeneity are determined by the secondary model parameter. The MLHEED protocol (for all level heterogeneity) considers two parameters for deciding the cluster heads, i.e., residual energy and node density. In this work, we illustrate the network model up to six levels. Experimentally, as the level of heterogeneity increases, the rate of energy dissipation decreases and hence the nodes stay alive for longer time. The MLHEED-1, MLHEED-2, MLHEED-3, MLHEED-4, MLHEED-5, and MLHEED-6 increase the network lifetime by 73.05%, 143.40%, 213.17%, 267.90%, 348.60%, respectively, by increasing the network energy as 40%, 57%, 68.5%, 78%, 84%, with respect to the original HEED protocol.

Red alga Palmaria palmata—growth rate and photosynthetic performance under elevated CO2 treatment

Marine macroalgae offer a feasible solution for reducing CO2 emissions by fixing CO2 as algal biomass and thus providing a source of renewable energy. The perennial red alga Palmaria palmata was cultivated and supplied with increased CO2 concentrations starting with 22 μmol kg−1 (pH 8.53) to 9770 μmol kg−1 (pH 6.04). Experiments covered test periods of 28 days, 7 days, and 2 h to examine the possible influence of different treatment durations. Biomass productivity over 28 days showed an increased production rate, which continuously declined with increasing CO2 concentration. After 7 days, the productivity was below the controls, suggesting a lag phase or necessary adaptation period to elevated CO2 concentrations of more than 7 days. Concerning the effects on maximum electron transport rate (ETRmax), light-harvesting efficiency (alpha), and light saturation of the photosynthetic electron transport (E k ), a stimulating influence was identified with the effect becoming more significant the shorter the test period was. The treatment with elevated CO2 concentrations for 28 days led to a decrease in photochemical efficiency (Y(II)) and regulated nonphotochemical energy dissipation (Y(NPQ)). In contrast, the treatment duration of 7 days predominantly increased photochemical quenching whereas the 2-h treatment resulted in a significant increase in photochemical quenching and in a significant decrease in nonregulated nonphotochemical energy dissipation. Hence, elevated CO2 concentrations over a prolonged time period interfered more distinctively with the fluorescence quenching ability of P. palmata.

An Enhanced Physically Based Scour Model for Considering Jet Air Entrainment

Abstract Based on systematic experiments on the influence of air entrainment on rock block stability in plunge pools impacted by high-velocity jets, this study presents adaptations of a physically based scour model. The modifications regarding jet aeration are implemented in the Comprehensive Scour Model (CSM), allowing it to reproduce the physical-mechanical processes involved in scour formation concerning the three phases; namely, water, rock, and air. The enhanced method considers the reduction of momentum of an aerated jet as well as the decrease of energy dissipation in the jet diffusive shear layer, both resulting from the entrainment of air bubbles. Block ejection from the rock mass depends on a combination of the aerated time-averaged pressure coefficient and the modified maximum dynamic impulsion coefficient, which was found to be a constant value of 0.2 for high-velocity jets in deep pools. The modified model is applied to the case of the observed scour hole at the Kariba Dam, with good agreement.

Impact of nanomagnets size on switching behaviour of all spin logic devices

Under different nanomagnets’ size, switching behaviour of all spin logic (ASL) devices constructed with Co and permalloy (Py) nanomagnets are studied by using the coupled spin-transport/magneto-dynamics model. The results indicate that ASL devices’ switching delay and energy dissipation can be reduced by decreasing the thickness of nanomagnets. The switching delay and energy dissipation of PyASL are lower than those of CoASL in a smaller thickness of nanomagnet, but they increase much faster than those of CoASL when the nanomagnets (FM) thickness increases. With the dimensional scaling of nanomagnets, the ASL devices’ switching delay and energy dissipation decrease rapidly and the influence of thermal noise become weak. Moreover, under the same nanomagnet volume, ASL devices’ switching delay, energy dissipation, and energy barrier can be reduced by decreasing aspect ratio. These findings can provide guidelines for optimising the ASL devices’ materials and size.

Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking.

Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p < 0.001) and increased the gear ratio (i.e., ratio of ground reaction force and plantar flexor muscle lever arms) (p < 0.001). Added foot stiffness also altered soleus muscle behaviour, leading to greater peak force (p < 0.001) and reduced fascicle shortening speed (p < 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p < 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors’ mechanical advantage.

Low end‐to‐end delay fuzzy networking protocol for mobile wireless sensing

AbstractBecause of the practical limitations of the energy and processing capabilities, the deployment of many Wireless Sensor Networks (WSN) is facing two main challenges of increasing network lifetime and reducing End to End Delay (EED) which become critical when the nodes are mobile and use non‐rechargeable energy sources. One way to help to extend network lifetime is using fuzzy logic in a form of artificial intelligence. To this end we propose a new routing protocol for using mobile WSNs, which holds the nodes in an equal level of energy and decreases energy dissipation of the network. An optimum path is selected based on the cost of each node to increase network lifetime. In order to lessen EED, we also attempt to design a novel zoning‐scheme for the network area. In this scheme, zonation is dynamic and works based on the Data Link (DL) position. The simulation result shows a significant improvement in lifetime and EED by proposed protocol compared with existing protocols. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Multilevel heterogeneous network model for wireless sensor networks

The lifetime of a network can be increased by increasing the network energy. The network energy can be increased either increasing the number of sensors or increasing the initial energy of some sensors without increasing their numbers. Increasing network energy by deploying extra sensors is about ten times costlier than that using some sensors of high energy. Increasing the initial energy of some sensors leads to heterogeneous nodes in the network. In this paper, we propose a multilevel heterogeneous network model that is characterized by two types of parameters: primary parameter and secondary parameters. The primary parameter decides the level of heterogeneity by assuming the values of secondary parameters. This model can describe a network up to nth level of heterogeneity (n is a finite number). We evaluate the network performance by applying the HEED, a clustering protocol, on this model, naming it as MLHEED (Multi Level HEED) protocol. For n level of heterogeneity, this protocol is denoted by MLHEED-n. The numbers of nodes of each type in any level of heterogeneity are determined by the secondary model parameter. The MLHEED protocol (for all level heterogeneity) considers two variables, i.e., residual energy and node density, for deciding the cluster heads. We also consider fuzzy implementation of the MLHEED in which four variables are used to decide the cluster heads: residual energy, node density, average energy, and distance between base station and the sensor nodes. In this work, we illustrate the network model up to seven levels ($$1\le n\le 7$$1≤n≤7). Experimentally, as the level of heterogeneity increases, the rate of energy dissipation decreases and hence the nodes stay alive for longer time. The MLHEED-m, $$m=2,3,4,5,6,7$$m=2,3,4,5,6,7, increase the network lifetime by $$73.05, 143.40, 213.17, 267.90, 348.60, 419.10\,\%$$73.05,143.40,213.17,267.90,348.60,419.10%, respectively, by increasing the network energy as $$40, 57, 68.5, 78, 84, 92.5\,\%$$40,57,68.5,78,84,92.5% with respect to the original HEED protocol. In case of fuzzy implementation, the MLHEEDFL-m, $$m=2,3,4,5,6,7,$$m=2,3,4,5,6,7, increases the network lifetime by $$282.7, 378.5, 435.78, 498.50, 582.63, 629.79\,\%$$282.7,378.5,435.78,498.50,582.63,629.79%, respectively, corresponding to the same increase in the network energy as that of the MLHEED (all levels) with respect to the original HEED. The fuzzy implementation of the HEED, MLHEEDFL-1, increases the network lifetime by $$176.6\,\%$$176.6% with respect to the original HEED with no increase in the network energy.

Turbulent flow structures in alluvial channels with curved cross‐sections under conditions of downward seepage

AbstractExperimental investigations have been done to analyze turbulent structures in curved sand bed channels with and without seepage. Measures of turbulent statistics such as time‐averaged near‐bed velocities, Reynolds stresses, thickness of roughness sublayer and shear velocities were found to increase with application of downward seepage. Turbulent kinetic energy and Reynolds normal stresses are increased in the streamwise direction under the action of downward seepage, causing bed particles to move rapidly. Analysis of bursting events shows that the relative contributions of all events (ejections, sweeps and interactions) increase throughout the boundary layer, and the thickness of the zone of dominance of sweep events, which are responsible for the bed material movement, increases in the case of downward seepage. The increased sediment transport rate due to downward seepage deforms the cross‐sectional geometry of the channel made of erodible boundaries, which is caused by an increase in flow turbulence and an associated decrease in turbulent kinetic energy dissipation and turbulent diffusion.

Corneal Deformation Response and Ocular Geometry: A Noninvasive Diagnostic Strategy in Marfan Syndrome

To evaluate corneal air-puff deformation responses and ocular geometry as predictors of Marfan syndrome. Prospective observational clinical study. Sixteen investigator-derived, 4 standard Ocular Response Analyzer (ORA), and geometric variables from corneal tomography and optical biometry using Oculus Pentacam and IOL Master were assessed for discriminative value in Marfan syndrome, measuring right eyes of 24 control and 13 Marfan syndrome subjects. Area under the receiver operating characteristic (AUROC) curve was assessed in univariate and multivariate analyses. Six investigator-derived ORA variables successfully discriminated Marfan syndrome. The best lone disease predictor was Concavity Min (Marfan syndrome 47.5 ± 20, control 69 ± 14, P = .003; AUROC = 0.80). Corneal hysteresis (CH) and corneal resistance factor (CRF) were decreased (Marfan syndrome CH 9.45 ± 1.62, control CH 11.24 ± 1.21, P = .01; Marfan syndrome CRF 9.77 ± 1.65, control CRF 11.03 ± 1.72, P = .01) and corneas were flatter in Marfan syndrome (Marfan syndrome Kmean 41.25 ± 2.09 diopter, control Kmean 42.70 ± 1.81 diopter, P = .046). No significant differences were observed in central corneal thickness, axial eye length, or intraocular pressure. A multivariate regression model incorporating corneal curvature and hysteresis loop area (HLA) provided the best predictive value for Marfan syndrome (AUROC = 0.85). This study describes novel biodynamic features of corneal deformation responses in Marfan syndrome, including increased deformation, decreased bending resistance, and decreased energy dissipation capacity. A predictive model incorporating HLA and corneal curvature shows greatest potential for noninvasive clinical diagnosis of Marfan syndrome.

Effects of Stepped Spillway Geometry on Flow Pattern and Energy Dissipation

In order to pass surplus water and inundation from upstream to downstream of dams, structure called spillway is used. Spillway and chutes are among important hydraulic structures which play a significant role in stability of dams. In some cases and when the slope is too steep to build a chute, in order to transfer water from upstream to downstream, a stepped spillway which is remarkably effective in energy dissipation is used. In the present study, in order to ascertain the effect of different parameters such as number of steps (Ns), step height (h), step length (L), and discharge in width unit (q) on energy dissipation in the simple stepped spillway, the model of Flow-3D was used, and the relationship between energy dissipation and flow critical depth in the stepped spillway was investigated. Further, the method of finite volume was used to solve the extant equations, and the model of K − ɛ was also used to investigate the flow turbulence. The results revealed that as the flow discharge increases, energy dissipation decreases and as the number of steps increases and their height decreases, energy dissipation decreases. Besides, the obtained findings were compared with the other researchers, empirical and mathematical studies and finally an acceptable coincidence was obtained.

Lapped-steel effects on bridge pier behavior under moderate near-fault motions

Extensive research for the Far Fault Ground Motion (FFGM) has been carried out in strong seismic regions, but limited research has been done for the Near Fault Ground Motion (NFGM) because of very few records. Shake table tests for NFGM were conducted to investigate the seismic behavior of Reinforced Concrete (RC) bridge columns with lap-spliced longitudinal bars that are designed in low or moderate seismic region. Seven RC column specimens with a height of 1400 mm (55.2 in) and a diameter of 400 mm (15.8 in) were tested on a shaking table, and one alike specimen was quasi-statically tested. The effect on lap-spliced longitudinal reinforcing steel was investigated. Shaking test results are compared to those of the quasi-static test. The displacement ductility was significantly decreased in RC column specimens with lap-spliced longitudinal reinforcing bars. The effect of NFGM is compared to that of FFGM. The NFGM specimen showed somewhat less seismic capacity than the FFGM model from Fig. 4(d). Decrease of displacement ductility and energy dissipation was observed in the shake table test specimens in comparison with the quasi-static model.

Area-Delay-Energy Tradeoffs of Strain-Mediated Multiferroic Devices

Multiferroic devices hold profound promise for ultra-low energy computing in beyond Moore's law era. The magnetization of a magnetostrictive shape-anisotropic single-domain nanomagnet strain-coupled with a piezoelectric layer in a multiferroic composite structure can be switched between its two stable states (separated by an energy barrier) with a tiny amount of voltage via converse magnetoelectric effect. With appropriate choice of materials, the magnetization can be switched with a few tens of millivolts of voltages in sub-nanosecond switching delay while spending a miniscule amount of energy of ~1 attojoule at room-temperature. Here, we analyze the area-delay-energy trade-offs of these multiferroic devices by solving stochastic Landau-Lifshitz-Gilbert equation in the presence of room-temperature thermal fluctuations. We particularly put attention on scaling down the lateral area of the magnetostrictive nanomagnet that can increase the device density on a chip. We show that the vertical thickness of the nanomagnet can be increased while scaling down the lateral area and keeping the assumption of single-domain limit valid. This has important consequence since it helps to some extent preventing the deterioration of the induced stress-anisotropy energy in the magnetostrictive nanomagnet, which is proportional to the nanomagnet's volume. The results show that if we scale down the lateral area, the switching delay increases while energy dissipation decreases. Avenues available to decrease the switching delay while still reducing the energy dissipation are discussed.

Strengthening of non-seismically designed beam-column joints by ferrocement jackets with chamfers

This paper presents a strengthening method that involves the use of ferrocement jackets and chamfers to relocate plastic hinge for non-seismically designed reinforced concrete exterior beam-column joints. An experimental study was conducted to assess the effectiveness of the proposed strengthening method. Four half-scale beam-column joints, including one control specimen and three strengthened specimens, were prepared and tested under quasi-static cyclic loading. Strengthening schemes include ferrocement jackets with or without skeleton reinforcements and one or two chamfers. Experimental results have indicated that the proposed strengthening method is effective to move plastic hinge from the joint to the beam and enhance seismic performance of beam-column joints. Shear stress and distortion within the joint region are also reduced significantly in strengthened specimens. Skeleton reinforcements in ferrocement provide limited improvement, except on crack control. Specimen strengthened by ferrocement jackets with one chamfer exhibits slight decrease in peak strength and energy dissipation but with increase in ductility as compared with that of two chamfers. Finally, a method for estimating moment capacity at beam-column interface for strengthened specimen is developed. The proposed method gives reasonable prediction and can ensure formation of plastic hinge at predetermined location in the beam.

Effect of fabric structure and polymer matrix on flexural strength, interlaminar shear stress, and energy dissipation of glass fiber-reinforced polymer composites

We report the effect of glass fiber structure and the epoxy polymer system on the flexural strength, interlaminar shear stress (ILSS), and energy absorption properties of glass fiber-reinforced polymer (GFRP) composites. Four different GFRP composites were fabricated from two glass fiber textiles of different fabric count and strand density and two resin systems, a cycloaliphatic and a linear aliphatic system. These composites were fabricated using the vacuum-assisted resin transfer method. The flexural stress and ILSS data were obtained using a three-point bending test following ASTM 790-10 and ASTM D2344/D2344M standards. The GFRP composite sheet fabricated using a larger fabric count showed weak flexural strength as well as poor ILSS properties. However, it showed an average increase in energy dissipation of 95% and 7%, for resins SC780 and SC15, respectively, after five compression cycles over the measured range of compression strain. In comparison with the SC15 resin, the SC780 resin proved to have better flexural and ILSS properties but decreased energy dissipation. The results of this investigation help with the design of textile-reinforced composites for applications where bending strength, ILSS, and energy absorption are important.

Effect of nanosilver in wheat seedlings and Fusarium culmorum culture systems

The purpose of this study was to examine the effect of silver nanoparticles (AgNPs) produced using the high-voltage arc discharge method on the growth and metabolism of common wheat seedlings. Additionally, a simultaneous assessment of the AgNP-induced reduction in seedling infection by Fusarium culmorum (Fc) was performed. AgNP- and Fc-treated seedlings indicated that both factors considerably inhibited their growth. A significant Fc-induced reduction in seedling blight was observed following treatment with AgNPs; however, treatment with nanoparticles was also accompanied by a serious disintegration of the cell membranes of roots. Moreover, treatment with AgNPs increased the quantum efficiency of energy trapping in the PSII reaction centre (Fv/Fm) with a simultaneous decrease in energy dissipation in the form of heat. Induction of photosynthesis in the presence of AgNPs did not affect height but was reflected in higher total dry weight. Moreover, analysis of antioxidant enzyme activity typical for the stress response indicated the toxicity of AgNPs treatment compared to Fc treatment. Seedlings exposed to AgNP activity demonstrated accumulation of Ag in roots and its translocation to aerial parts, while the pathogen reduced both accumulation and translocation of this element.

IMPACT OF SPILLWAY CONVERSION ON FLOW CHARACTERIS

Conversed spillway may be some-times considered the best shape from the application point of view according to the dam site. The main function of spillway is energy dissipation. So studying the effect of the spillway conversion on the energy dissipation is very important, In this study the downstream width and the angle of conversion were tested experimentally. The dimensional analysis was used to correlate the different parameters affecting the studied phenomena. Beside that the continuity and one-dimension al momentum equation were used to calculate froud number to derive a theoretical equation for the tail water depth. Also, an equation for the loss of energy was denved using the energy conseration equation It was found that conversion decreases energy dissipation and increases downstream water depth. The theoretical results were found to be in a good agreement with the experimental data. Finally, the results of this study could be recommended in the field of applications.

Contact mechanics analysis of oscillatory sliding of a rigid fractal surface against an elastic–plastic half-space

Oscillatory sliding contact between a rigid rough surface and an elastic–plastic half-space is examined in the context of numerical simulations. Stick-slip at asperity contacts is included in the analysis in the form of a modified Mindlin theory. Two friction force components are considered – adhesion (depending on the real area of contact, shear strength and interfacial adhesive strength) and plowing (accounting for the deformation resistance of the plastically deformed half-space). Multi-scale surface roughness is described by fractal geometry, whereas the interfacial adhesive strength is represented by a floating parameter that varies between zero (adhesionless surfaces) and one (perfectly adhered surfaces). The effects of surface roughness, apparent contact pressure, oscillation amplitude, elastic–plastic properties of the half-space and interfacial adhesion on contact deformation are interpreted in the light of numerical results of the energy dissipation, maximum tangential (friction) force and slip index. A non-monotonic trend of the energy dissipation and maximum tangential force is observed with increasing surface roughness, which is explained in terms of the evolution of the elastic and plastic fractions of truncated asperity contact areas. The decrease of energy dissipation with increasing apparent contact pressure is attributed to the increase of the elastic contact area fraction and the decrease of the slip index. For a half-space with fixed yield strength, a lower elastic modulus produces a higher tangential force, whereas a higher elastic modulus yields a higher slip index. These two competing effects lead to a non-monotonic dependence of the energy dissipation on the elastic modulus-to-yield strength ratio of the half-space. The effect of interfacial adhesion on the oscillatory contact behaviour is more pronounced for smoother surfaces because the majority of asperity contacts deform elastically and adhesion is the dominant friction mechanism. For rough surfaces, higher interfacial adhesion yields less energy dissipation because more asperity contacts exhibit partial slip.

Modification of the mechanical properties of carbon nanotube arrays using electron irradiation induced oxidation

This paper describes a method of altering the compliance and adhesion of nominally vertically aligned multi-walled carbon nanotube (CNT) arrays (“turfs”) using oxidation caused by electron irradiation from typical imaging conditions in a scanning electron microscope. A combination of electron microscopy and infrared spectroscopy demonstrates that typical imaging conditions lead to the deposition and further oxidation of amorphous carbon on CNT turfs. The elastic modulus of the turfs, as measured by nanoindentation, decreases from approximately 100 to 50 MPa after irradiation and exposure to ambient laboratory conditions. The adhesion between the diamond indenter tip and turf is effectively eliminated once the amorphous carbon coated the turfs. In addition, the CNT turf exhibits decreased energy dissipation capabilities and a decreased viscoelastic response during contact loading. This suggests that further research on characterization of CNT turfs should consider the possibility that electron beam exposure during imaging may impact the subsequently measured properties, and that to lessen these effects, imaging times and accelerating voltages should be minimized.

High-Throughput Compact Delay-Insensitive Asynchronous NoC Router

A new asynchronous delay-insensitive data-transmission method based on level-encoded dual-rail (LEDR) encoding with novel packet-structure restriction is proposed to realize a high-throughput network-on-chip (NoC) router together with a compact hardware. The use of LEDR encoding makes communication steps and the registers being used half in comparison with four-phase dual-rail encoding because the spacer information of the four-phase one is eliminated, which significantly improves the network throughput. By using the proposed packet structure, the phase information of header and tail flits is uniquely determined. Since the router can be asynchronously controlled by ignoring the phase information, the circuit is compactly implemented. As a result, the proposed asynchronous NoC router on a $(0.13\hbox{-}\mu m)$ CMOS technology, has a 90 percent increase in throughput and a 34 percent decrease in energy dissipation with 25 percent area overhead in comparison with a conventional four-phase asynchronous NoC router under a postlayout simulation. Under a random traffic pattern in a $(4\times 4)$ 2D mesh topology, the proposed asynchronous NoC has a 140 percent increase in throughput and half packet latency compared with the conventional one. We also fabricate the asynchronous NoC based on the proposed router on a $(0.13\hbox{-} \mu m)$ CMOS technology and demonstrate the chip correctly operates under a supply voltage of 0.6 to 1.8 V.

Analysis of novel low specific speed pump designs

Centrifugal pumps with very low specific speed present significant design challenges. Narrow blade channels, large surface area of hub and shroud discs relative to the blade area, and the presence of significant of blade channel vortices are typical features linked with the difficulty to achieve head and efficiency requirements for such designs. This paper presents an investigation of two novel designs of very low specific speed impellers: impeller having blades with very thick trailing edges and impeller with thick trailing edges and recirculating channels, which are bored along the impeller circumference. Numerical simulations and experimental measurements were used to study the flow dynamics of those new designs. It was shown that thick trailing edges suppress local eddies in the blade channels and decrease energy dissipation due to excessive swirling. Furthermore the recirculating channels will increase the circumferential velocity component on impeller outlet thus increasing the specific energy, albeit adversely affecting the hydraulic efficiency. Analysis of the energy dissipation in the volute showed that the number of the recirculating channels, their geometry and location, all have significant impact on the magnitude of dissipated energy and its distribution which in turn influences the shape of the head curve and the stability of the pump operation. Energy dissipation within whole pump interior (blade channels, volute, rotor- stator gaps) was also studied.