Total Energy Flow Research Articles

Untangling the complex food webs of tropical rainforest streams.

Food webs depict the tangled web of trophic interactions associated with the functioning of an ecosystem. Understanding the mechanisms providing stability to these food webs is therefore vital for conservation efforts and the management of natural systems. Here, we first characterised a tropical stream meta-food web and five individual food webs using a Bayesian Hierarchical approach unifying three sources of information (gut content analysis, literature compilation and stable isotope data). With data on population-level biomass and individually measured body mass, we applied a bioenergetic model and assessed food web stability using a Lotka-Volterra system of equations. We then assessed the resilience of the system to individual species extinctions using simulations and investigated the network patterns associated with systems with higher stability. The model resulted in a stable meta-food web with 307 links among the 61 components. At the regional scale, 70% of the total energy flow occurred through a set of 10 taxa with large variation in body masses. The remaining 30% of total energy flow relied on 48 different taxa, supporting a significant dependency on a diverse community. The meta-food web was stable against individual species extinctions, with a higher resilience in food webs harbouring omnivorous fish species able to connect multiple food web compartments via weak, non-specialised interactions. Moreover, these fish species contributed largely to the spatial variation among individual food webs, suggesting that these species could operate as mobile predators connecting different streams and stabilising variability at the regional scale. Our results outline two key mechanisms of food web stability operating in tropical streams: (i) the diversity of species and body masses buffering against random and size-dependent disturbances and (ii) high regional diversity and weak omnivorous interactions of predators buffering against local stochastic variation in species composition. These mechanisms rely on high local and regional biodiversity in tropical streams, which is known to be strongly affected by human impacts. Therefore, an urgent challenge is to understand how the ongoing systematic loss of diversity jeopardises the stability of stream food webs in human-impacted landscapes.

Disturbance intensity shapes the soil micro-food web compositions and energy fluxes during seven-year land use changes

Soil micro-food webs play an important role in ecosystem functions through energy flow; they are strongly influenced by land use types. Previous studies have typically utilized the space-for-time substitution or single-time sampling method to reflect the land-use change effects by comparing differences among existing land-use types. These methods would increase random error. Research on how synchronized land-use change (starting at the same time and place) influences soil ecological processes and functions is urgently needed. Based on a controlled field experiment and seven years of observations, this study explored the effects of land-use change from natural shrubland to cropland (maize), forage land (tall-grass forage), and economic forest land (walnut plantation) on the community structure and energy dynamics of the soil micro-food webs. Cropland simplified the complexity of the soil food webs compared to the other three land-uses. Forage grassland maintained the highest biomasses of soil total microbes, fungi, and arbuscular mycorrhizal fungi. In addition, economic forest land improved the flow uniformity of the micro-food web by increasing energy transfer from resources to bacterivores, fungivores, and herbivores while decreasing herbivore energy flow to omnivores-predators. Omnivore abundance and nematode diversity were important predictors of total energy flux and flow uniformity of the soil micro-food webs, respectively. In addition, omnivores maintained the complexity of soil micro-food webs by promoting interactions among trophic groups through top-down control. Soil organisms are sensitive to the response of agricultural management and planting time, and it may take several years or more to reach a dynamic equilibrium. Different types and levels of ecosystem disturbance (e.g., tillage and no-tillage, fertilizer rates, aboveground biomass removal intensity) may be the major drivers of soil community during land use change. Our findings highlight the importance of conservation agriculture in maintaining soil food web structure and energy flow for future sustainable land uses, and that promoting omnivore abundance is essential for food web complexity and stability.

Reexamining “Free Energy Rate Density” as a Complexity Metric

Cosmic Evolution, by Eric J. Chaisson is arguably one of the original “core” texts of big history. Despite being published over 20 years ago, it is still relevant for its explanation of the cosmological and thermodynamic underpinnings of the evolution of complex systems over the span of time. It was also a pioneering work because it proposed that we can quantify the degree of complexity of systems by determining the quantity of the “free energy rate density” or FERD (abbreviated as “Ωm” in Cosmic Evolution) that flows through a system. Although Chaisson advises that his correlations of FERD to complexity degree is subject to various limitations and generalizations, careful analysis of the arguments and examples used to support FERD indicates that it is even less likely to be as reliable and quantifiable than he purports for at least the following reasons:1. The author offers a relatively short list of criteria for a system to qualify being “complex” that in turn results in the inclusion of systems that are not classified as complex by usual criteria. 2. Free energy rate density is not compared against other complexity metrics and subsequently seems to serve as its own “gold standard.” The lack of comparisons results in a tautological argument and sometimes questionable conclusions.3. The argument for FERD sometimes deviates from the hypothesis that FERD is a good way to measure the degree of a system’s complexity to a claim that it also measures complex functions and structures as well. 4. The FERD that he reports are often actually for the total energy flow through a system. Hence, a much more efficient complexity might only appear to be less complex. 5. Complex systems have many variables that can confound attempts to make reliable and precise generalizations, including good metrics for their degree.

Relationship between Phytoplankton, Heterotrophic Plankton, and Planktivorous Fish Productions in Different Water Bodies.

Examination of 14 lake-type water bodies at various latitudes of the Northern Hemisphere showed that the efficiency of phytoplankton production transformation through heterotrophic bacterioplankton and non-predatory zooplankton to predatory zooplankton and planktivorous fish increases in the direction from eutrophic to oligotrophic water bodies. The highest ratios between autotrophic and heterotrophic organism production were observed in lakes and reservoirs where the contribution of allochthonous substances to the total energy flow is relatively high. Bacterioplankton utilizing allochthonous dissolved organic matter (DOM) provides an additional source of energy for zooplankton, which serves as food for planktivorous fish. Therefore, to predict the total biological productivity and production of the fish community, it is necessary to take into account the production of not only autotrophic plankton, but also that part of heterotrophic bacterioplankton that is specialized in utilizing DOM entering the water body from the outside.

Multiple fields generated by two dissimilar conductive punches on thermoelectric material

Exposed to high load concentrations environments such as mechanical, thermal, and electrical, thermoelectric equipment may be damaged by the contact surface during operation, resulting in equipment failure. The effects of two dissimilar rigid punches on the thermoelectric material layer under mechanical force and thermoelectric loading are investigated in this article. Using the Fourier transform, the problem is turned into a system of three singular integral equations containing the thermoelectric effect, and the collocation methods are used to solve it numerically. The effects of thermoelectric load, thermoelectric material layer thickness, and the distance between two punches on the electric current density, energy flux, and surface normal stress distribution are thoroughly discussed. The results show that when the two punches are close to each other, below the two punches, the electric current density, energy flux, and contact stress values are larger near the distal end and lower at the inner edge. The stresses at the inner edge of the two indices show opposite characteristics with an increasing of total energy flow and total current, whereas they are consistent at the outer edge. The results aid in the measurement of the multifield coupling properties of finite-thickness thermoelectric material using indenter experiments.

Theory of Transfer, Storage and Dissipation of Energy in Circuits

Energy transfer accompanying with current is usually described by using Poynting’s vector. Here, combining Kirchhoff’s law, Joule’s law and Slepian’s postulation, we demonstrate that, for the case of a current travels along a wire, component of total energy flow flux parallel to the wire (CTEFFPW) may be equivalently described by using product of current intensity and electric potential (voltage), furthermore, the law of conversion and conservation of energy accompanying with current, which is equivalent to Poynting’s theorem, may be obtained based on circuit method. Noting that product of current intensity and voltage relates to CTEFFPW instead of the electric power, physical meaning of usual definitions of powers adopted in electric power theory are readdressed. Our work may provide possibility to achieve the long-time expectation that power properties of power systems are described on the basis of Poynting’s theorem and Poynting’s vector, and to address the unsolved problems arised in the electric power theory.

Prospective, Randomized, Double-blind, Placebo-controlled, Pilot Study of Extracorporeal Shock Wave Therapy for Detrusor Underactivity/Underactive Bladder

BackgroundDetrusor underactivity/underactive bladder (DU/UAB) is a disease with great unmet needs and no current approved drug treatment. Extracorporeal shock wave therapy (ESWT) has been shown to improve regeneration of tissue and increase detrusor contractility in preclinical studies of DU/UAB. ObjectiveTo assess ESWT as a treatment of DU/UAB. Design, setting, and participantsPatients with DU/UAB were enrolled in this phase 2 randomized, double-blind, placebo-controlled, physician-initiated study. InterventionThe patients were assigned to ESWT (N = 6, 2500 shocks, frequency of four pulses per second, and maximum total energy flow density of 0.25 mJ/mm2) once a week for 6 wk at the suprapubic bladder area or to placebo (N = 5, shock wave setting without energy transmission). Outcome measurements and statistical analysisThe primary endpoint was the average changes in postvoid residual urine (PVR) from baseline to 4 wk after treatment. Other endpoints included the average changes in 3-d voiding diary, global response assessment of patient satisfaction, Underactive Bladder Questionnaire (UAB-Q) score, and urodynamic evaluation. Results and limitationsThe difference in improvement in PVR was −157.8 ml (95% confidence interval [CI]: −380.1, 64.4) versus −6.6 ml (95% CI: −178.1, 164.9) and −77.5 ml (95% CI: −242.1, 87.1) versus 81.8 ml (95% CI: −137.2, 300.7) for ESWT versus placebo (p = 0.116 and 0.056) at 4 and 12 wk, respectively. The ESWT group exhibited a significant reduction in the UAB-Q score (−4.3; 95% CI: −9.1, 0.4) compared with the placebo group (−0.4; 95% CI: −1.8, 1.0) at 4 wk after treatment (p = 0.025), and the effects were decreased at 12 wk (p = 0.091). This study was limited by small sample size. ConclusionsESWT was well tolerated with a statistically significant decrease of DU/UAB symptoms and a trend to decrease PVR versus placebo. These results indicate that ESWT may be a promising treatment for DU/UAB and multicenter studies are needed. Patient summaryBladder shock wave therapy was studied in this randomized, double-blind, placebo-controlled study in patients with inadequate bladder emptying (underactive bladder). Bladder shock wave therapy was found to be well tolerated with an improvement in bladder emptying. These results indicate that bladder shock wave therapy may be a promising treatment for patients who cannot empty their bladder adequately.

How plants conquered land: evolution of terrestrial adaptation.

The transition of plants from water to land is considered one of the most significant events in the evolution of life on Earth. The colonization of land by plants, accompanied by their morphological, physiological and developmental changes, resulted in plant biodiversity. Besides significantly influencing oxygen levels in the air and on land, plants manufacture organic matter from CO2 and water with the help of sunlight, paving the way for the diversification of nonplant lineages ranging from microscopic organisms to animals. Land plants regulate the climate by adjusting total biomass and energy flow. At the genetic level, these innovations are achieved through the rearrangement of pre-existing genetic information. Advances in genome sequencing technology are revamping our understanding of plant evolution. This study highlights the morphological and genomic innovations that allow plants to integrate life on Earth.

The energy flow of moving vehicles for different traffic states in the intersection

To clarify the impact of steady traffic (ST) and stop-go traffic (SGT) on the energy flow of moving vehicles contributes to a deeper understanding of signalized intersection’s traffic optimization mechanism. In this paper, the theoretical model of vehicle energy was improved based on vehicle driving states, 3 energy evaluation indexes were proposed, and 6 vehicle cycles experiments were carried out in ST and SGT. The results show that: (1) The internal energy consumption of vehicles is the main direction of the total tank energy flow of vehicles, ST reduces the flow intensity of total tank energy to internal energy by 1.2% and increases the distribution force to friction energy consumption by 22.9%, which makes the energy distribution of moving vehicles more uniform. (2) ST weakens the influence of speed on air resistance energy consumption by 59.1%, and its regulatory effect on air resistance energy consumption is stronger than that of friction energy consumption. (3) Energy conservation equation of moving vehicles is formed and coefficients’ physical significance is explained. The study provides a theoretical basis for the optimization and management of signalized intersections.

Coverage Path Planning Based on the Optimization Strategy of Multiple Solar Powered Unmanned Aerial Vehicles

In some specific conditions, UAVs are required to obtain comprehensive information of an area or to operate in the area in an all-round way. In this case, the coverage path planning (CPP) is required. This paper proposes a solution to solve the problem of short endurance time in the coverage path planning (CPP) problem of multi-solar unmanned aerial vehicles (UAVs). Firstly, the energy flow efficiency based on the energy model is proposed to evaluate the energy utilization efficiency during the operation. Moreover, for the areas with and without obstacles, the coverage path optimization model is proposed based on the undirected graph search method. The constraint equation is defined to restrict the UAV from accessing the undirected graph according to certain rules. A mixed integer linear programming (MILP) model is proposed to determine the flight path of each UAV with the objective of minimizing operation time. Through the simulation experiment, compared with the Boustrophedon Cellular Decomposition method for coverage path planning, it is seen that the completion time is greatly improved. In addition, considering the impact of the attitude angle of the solar powered UAV when turning, the operation time and the total energy flow efficiency are defined as the optimization objective. The bi-objective model equation is established to solve the problem of the CPP. A large number of simulation experiments show that the optimization model in this paper selects different optimization objectives and applies to different shapes of areas to be covered, which has wide applicability and strong feasibility.

Temporal Dynamics in Energy Fluxes and Trophic Structure of a Portunus trituberculatus Polyculture Ecosystem During Different Culture Periods

Swimming crab (Portunus trituberculatus) are an important aquaculture species in eastern coastal areas of China. To improve the understanding of P. trituberculatus culture ecosystem functioning, the dynamics of energy flow and trophic structure of a P. trituberculatus polyculture system (co-culture with white shrimp Litopenaeus vannamei and short-necked clam Ruditapes philippinarum) were investigated in this study. Three Ecopath models representing the early, middle, and late culture periods of a P. trituberculatus polyculture ecosystem, respectively, were constructed to compare ecosystem traits at different culture periods. The results demonstrated that detritus was the main energy source in this polyculture ecosystem, and most of the total system throughput occurred at trophic levels I and II. Artificial food input and consumption by the culture organisms increased from early to middle and late periods, which produced marked impacts on biomass structure and primary production. R. philippinarum was considered to have a dominant influence on phytoplankton community dynamics which changed from nano- to pico-phytoplankton predominance, from the middle to the late period. Considering the low utilization efficiency of pico-phytoplankton production, large amounts of detritus accumulated in the sediment in the late period, which may constitute a potential risk for the ecosystem. Ecological network analyses indicated that the total energy flow and level of system organization increased from the early to the middle and late periods, whereas food web complexity and system resilience decreased from early to middle and late periods, which may indicate a trend of decreasing ecosystem stability. The system may be further optimized by increased stocking density of R. philippinarum and by introducing macro-algae at a suitable biomass to increase ecosystem stability, energy utilization efficiency, and aquaculture production.

Nonlinear Surface Polaritons near the Interface between a Magneto-Optical Substance and a Nonlinear Metamaterial with a Permittivity Close to Zero

Relevance. Considerable attention of researchers is drawn to nonlinear surface optical waves, as they are promising for application in optical information processing systems, ultra-sensitive sensors, and modern telecommunications components. Purpose. To obtain an exact solution of the Maxwell equation system for TM-polarised nonlinear surface polaritons propagating along the interface between an optically linear magnetic medium and an optically nonlinear medium with saturated nonlinearity. Methods. Analysis of the properties of nonlinear surface polaritons (NSP) and mathematical modelling of the dependence of the permittivity of a nonlinear medium on the intensity are used. Results. TM-polarised nanoparticles propagating along the interface of a magneto-optical medium and a nonlinear optical metamaterial with a permittivity close to zero (ENZ-metamaterial) are studied. For NSP in such a structure, an exact solution of the Maxwell equation system is obtained, considering the saturation effect of optical nonlinearity. On this basis, the dependences of constant propagation on the total energy flux of NSP and energy fluxes in contact media in the structure were investigated: magneto-optical ENZ-metamaterial with negative permittivity/nonlinear self-focusing ENZ-metamaterial. Conclusions. The NSP energy flow is positive in a nonlinear medium and negative in a linear one. As the saturation level decreases, the NSP energy fluxes in the contacting media increase modulo, if the value of the NSP propagation constant (NSPPC) is fixed. The lowest NSPPC value for guiding nonlinearity is obtained when the total energy flow of the NSP becomes zero. As the saturation level decreases, the NSP propagation variable (NSPPV) increases. At a fixed NSPPC, with a decrease in the magnetic permeability, the energy fluxes of NSP in the contacting media increase. When the magnetic permeability decreases to zero and the NSP energy flux is positive, the NSPPV change range narrows

Gross energetics in the evaluation of the functioning of Instructional Dairy Farm at Pantnagar, India

Instructional Dairy Farm at Pantnagar University was studied for evaluating its energetic efficiency, an importantmeasure to evaluate the functioning of a production system. The total organic inputs and outputs of the dairy farmwere converted into their respective energy values. Of the total energy flows involved in the dairy farm, 72.6% wasthe input energy suggesting that most of the energy flow in the dairy farm takes place through feeds. Of the totalenergy output, dung accounted for 54.83% and milk 44.86%. Only 0.31% of the total output energy was containedin the new born calves. The energy balance of the dairy farm reflected that dung was the most important product,though milk was regarded as most valuable product as it is used for direct human consumption. Gross energeticefficiency of the farm worked out to be 37.7%. This reflects that 62.3% of the total energy was being used for nonproductive purposes (methane production or others).

Transformations of structurally stable states of spiral beams subjected to sector perturbations

We investigated conditions for the violation of the structural stability of a spiral beam subject to sector perturbations. Based on the method of computer simulation and measurement of mode spectra, we have shown that a spiral vortex beam has a characteristic caustic surface, the intersection of which sharply changes the shape of the Poynting vector streamlines and the total topological charge of the beam. Sector beam perturbation does not almost change the streamline structure up to scale and rotation. We found that perturbation of the beam causes a change in the direction of circulation of streamlines in the region of perturbation, which is caused by the appearance of vortices with negative topological charges. Their contribution to the total energy flow is fractions of a percent. However, such perturbations do not cause changing the OAM in the beam, despite an increase in the number of vortex modes. Nevertheless, the perturbed beam remains only conditionally structurally stable due to the presence of a small fraction of optical currents with opposite circulations.

Effects of sample gear on estuarine nekton assemblage assessments and food web model simulations

Long-term fisheries-independent sampling data inform population status and trends of species-specific biomass and are often used to drive biomass-based food web models such as the Comprehensive Aquatic Systems Model (CASM). Indicators such as total biomass and mean trophic level derived from these data and from CASM outputs inform management and facilitate assessments of on-going and predicted coastal change and restoration activities on fisheries, but rely on consistent sampling to enable comparisons across space and time. Changes in coastal estuarine gradients, combined with the availability of new sampling technologies, highlight a need to assess the potential consequences of changing sampling technologies on fisheries data and the cascading impact on model outputs. In Louisiana, USA, CASM models are used to inform coastal restoration projects, relying on 40 years of fisheries-independent data derived from 50′ seine sampling. However, alternative use of electrofishers as a sampling method has been proposed to replace the seine sampling. In this study, we examine data from concurrent seine and electrofisher sampling in Barataria Basin, Louisiana, and compare biomass, assemblage data and CASM outputs related to species biomass, food web structure and energy cycling. In a paired comparison of data in 2018–2019, the electrofisher captured higher total catch and diversity compared to the seine. The electrofisher samples were dominated by shrimp (grass, white, brown) and larger bodied fish, while seine samples were dominated by smaller-bodied fish (i.e., anchovy, menhaden). Ecosystem indicators derived from running the CASM using biomass data from seine and electrofisher sampling separately in two different simulation exercises provide contrasting results. In Simulation Exercise 1, the use of different datasets (long-term CASM calibration, 2018–2019 seine, 2018–2019 electrofisher) to initialize the CASM biomasses did not result in large or long-running changes in the simulated biomasses over time. In contrast, in Simulation Exercise 2, CASM model outputs using adjusted gear ratios indicated changes in biomass structure when using electrofisher data, with a doubling of total food web biomass due to the increased shrimp count, and a 13% increase in total energy flow through the food web. Conversions based on area and gear efficiency for overall catch may be useful in maintaining the continuity of historical data. However, differences in species-specific catch due to gear selectivity could have large consequences for constructing and calibrating fish and ecosystem models and remain difficult to reconcile. These differences in assemblages, and estimated biomasses for key food web species, suggest careful consideration in changing gears.

Identification of the Technical Condition of Induction Motor Groups by the Total Energy Flow

The paper discusses the method of identifying the technical condition of induction motors by classifying the energy data coming from the main common power bus. The work shows the simulation results of induction motor operation. The correlation between occurring defects and current diagrams is presented. The developed simulation model is demonstrated. The general algorithm for conducting experiments is described. Five different experiments to develop an algorithm for the classification are conducted: determination of the motors number in operation with different power; determination of the motors number in operation with equal power; determination of the mode and load of induction electric motor; determination of the fault and its magnitude with regard to operation and load of induction motor; determination of the fault and its magnitude with regard to operation and load of induction motor with regard to non-linear load in the flow. The article also presents an algorithm for preprocessing data to solve the classification problem. In addition, the classification results are shown and recommendations for testing and using the classification algorithm on a real object are made.

PSVIII-12 An economic and emergy approach to evaluate the level of sustainability of lamb production: A case study in Brazil

Abstract This study employed the Economic Theory (ET) to calculate the production costs and the Emergy Methodology (EM) to identify the contributions of nature and economy of lambs produced in an intensive system located in Cravinhos city, State of São Paulo. In addition, was employed Emergy Methodology (EM) to identify the contributions of nature and economy in the system. The adopted scheme of cost allocation followed the classification according to ET, under Variable Cost (VC), Operational Fixed Cost (FC), Opportunity Costs of land and capital (OC), and Total Cost (TC). The EM manages to quantify all the resources used in the system in Contributions from Nature (I) and Feedback from the economy (F). The I originate from the Sum of Renewable (R) and Non-renewable (N) local resources, while that F is composed of the Materials (M) and Services (S) from the economic system. We found that to produce 935 lambs per year the TC was US$ 96,021.08. VC represented 19.08% of TC, while 76.6% were represented by FC, and 4.3% by the IF. The cost produced per animal and kg of live weight was US$ 72.73 and US$ 1.82, respectively. On the other hand, the total energy flow (Y) required by the system was 3.05E+16 seJ/yr (Solar Joules per year) for produce (Ep) 1.68E+06J/yr (Joules per year). Y was represented in a 53.92% by I (7.98% for R, from the sun, rain, and wind; and 45.94% for N, from the soil loss and groundwater), and 46,08% by F (27.8% for M, from the feed, minerals, steel, fueled, etc. and 10.7% for S, from manpower, other services external, taxes, etc.). These results show that the studied system has a %Renewability (%R = R / Y) of 7.98%. Thus, we can conclude that the system depends on 92.02% of resources from non-renewable sources.

Comparison of the 2010 and 2020 ecosystem structures in Xihu Harbor based on the Ecopath model

The Ecopath with Ecosim modeling software was used to construct a Ecopath model for two time periods based on the 2010 and 2020 Xihu Harbor marine ecological environmental survey data. Changes in the Xihu Harbor ecosystem structure over the 10 years were determined, and management recommendations were proposed. The model includes 20 functional groups such as detritus, phytoplankton, Spartina alterniflora, zooplankton, benthic mollusks, Sciaenidae, other planktivorous fish, other piscivorous fish, and sea birds, and cover the Xihu Harbor ecosystem energy flow pathways. The analysis results showed that the types and biomass of important organisms changed during the 10 years; the total resources drastically decreased, fishery resources decreased by almost half, benthic organisms and plankton increased, and the mean ecotrophic efficiency decreased slightly (from 0.493 to 0.472). In 2010, the total energy flow from primary producers to each trophic level was 1406 t/km2·a, and the total energy flow from detritus to each trophic level was 1559 t/km2·a. In 2020, the total energy flow from primary producers to each trophic level was 2628 t/km2·a, and the total energy flow from detritus to each trophic level was 2751 t/km2·a. The energy input from primary producers and detritus in the Xihu Harbor ecosystem increased significantly. This was because macroalgae cultivation and expansion of S. alterniflora increased primary productivity as well as the expansion of the scale of mariculture, which increased detritus biomass and supported a high amount of energy flow through the system. The main reasons for changes in the Xihu Harbor ecosystem structure were S. alterniflora invasion, changes in aquaculture structure, and the decline in fishery resources. We propose targeted marine management measures, including using local salt marsh plants to replace S. alterniflora to maintain high primary productivity, continuing optimization to improve mariculture structure, and strengthening the seedling release of marine organisms.

A Thermo-Hydrodynamic Model for Thermal Energy Flow Management in A (Semi) Floating Ring Bearing System for Automotive Turbochargers

Abstract Oil-engine lubricated turbochargers (TCs) operate at high temperature and must withstand large temperature gradients that produce severe thermomechanical stresses in the TC mechanical components. Thus, an insight into the thermal energy flows and an effective thermal management are paramount to ensure reliable TC operation. The paper analyzes the transport of energy and heat flows in semifloating ring bearings (SFRBs) for automotive TCs with integrated heat and fluid flow models for both (turbine and compressor sides) radial bearings and thrust bearings to produce a complete thermohydrodynamic analysis predictive tool. The model couples the energy transport equations and the lubrication Reynolds equations in the inner and outer films of an SFRB and the adjacent thrust films to a three-dimensional heat conduction in the floating ring and along with thermal soaking into the TC casing. Cold lubricant, supplied at a specific temperature and pressure, flows to fill the films of the radial bearings, and then the thrust bearings. The lubricated bearings, radial and axial, support shaft loads, static and dynamic, and produce drag power losses. The streams of lubricant warm up as they take away a sizable portion of the heat flow from the hot shaft plus that due to viscous shear drag. Another fraction of thermal energy flow sinks into the floating ring, which presents a distinct temperature field varying along the radial, circumferential, and axial directions. The computational analysis contemplates a TC operating at shaft speeds (Ω) ranging from 30 krpm to 240 krpm (4 kHz) and an SFRB supplied with engine oil at PSUP = 3.0 bar and TSUP = 120 °C. The analysis focuses on a brass-made turbine bearing (TB) as it is the one that disposes most thermal energy flow since the shaft surface is hot at Ts = 213 °C (just below the lubricant flash point temperature at 230 °C) while the casing temperature is TC = TSUP. The ring with length/diameter = 1.6 has radial bearings with four equally spaced feed holes and four axial grooves, and the ratio outer film clearance/inner film clearance equals 5.3 at room temperature. As shaft speed increases (= 100 m/s max. surface speed), the inner film temperature increases proportionally; albeit the heat flow from the shaft into the inner film decreases while the viscous drag power raises rapidly. The outer film heats to just a few degrees above TSUP since the nonspinning ring does not generate viscous shear drag. The ring heats unevenly, radially with a ∼20 °C temperature gradient from its inner to outer diameters (ID and OD), and axially with up to a ∼50 °C difference from the thrust bearing side that also produces a drag power loss. At a low shaft speed (45 krpm), heat flowing from the shaft overwhelms the drag power loss induced by shearing the inner film; whereas as shaft speed increases (240 krpm), the contribution from the drag power loss to the total energy flow disposed increases significantly, from 3% to 63%. The lubricant flows, inner plus outer, advect most of the thermal energy flow, 74% to 81%, over the range of shaft speeds, low to high. The floating ring conducts a sizeable portion of thermal energy flow, 39% to 49% of the total, though varying little with shaft speed. Similarly does the fraction of heat, 9% to 13% of the total, conducted into the TC casing. A more conductive ring material or an outer film with a longer length conduct more heat into the ring although the lubricant flows still carry most of the thermal energy flow generated by viscous drag losses and heat from the shaft. The results demonstrate the importance of designing an SFRB system with adequate clearances and proper materials to offer an adequate thermal management and avoiding too high temperatures that could varnish, even flash and burn, the engine oil. The improvements in the energy transport and heat flow modeling of an SFRB system will produce significant savings in TC performance.

The Effect of the Interaction of Excitations with the Interface between Nonlinear Media with a Switching on the Formation of Localized States

Models of contacting media with stepwise nonlinearity are considered in the presence of interaction of excitations with the interface as a planar defect. In such media, an instantaneous switching from one level to another occurs when the field amplitude reaches a certain threshold value. New types of localized states with specific structure and properties are found. The structure of such states is determined by the formation of domains in the near-boundary regions, in which the values of certain parameters of the media differ from those in other regions. It is shown that, in the presence of interaction of excitations with the interface, new phenomena may occur that are related to the structural features of the field of localized states. The conditions for the existence of localized states are changed. The field can be maximized not only in the near-boundary region but also at the interface between a medium with stepwise nonlinearity and a linear medium. In the medium with stepwise nonlinearity containing a planar defect, the interaction of excitations with this defect leads to a decrease in the amplitude in the plane of the defect. As the intensity of interaction with the defect increases at a fixed localization energy, the domain width increases. It is shown that the threshold value of the total energy flow starting from which localized states exist and a domain is formed can be controlled by the intensity of the interaction of excitations with the interface.