Transition Of Regime Research Articles

Dictating Democracy: the Impact of Governor Baltia's Transitory Regime on Local Government In Eupen-malmedy, 1919-1922.

(2011). Dictating Democracy: the Impact of Governor Baltia's Transitory Regime on Local Government In Eupen-malmedy, 1919-1922. The International Journal of Regional and Local Studies: Vol. 7, The Rise and Fall of European Municipal Power since 1800, pp. 162-187.

Gas–liquid two-phase flows in rectangular polymer micro-channels

This study addresses gas–liquid two-phase flows in polymer (PMMA) micro-channels with non-molecularly smooth and poorly wetting walls (typical contact angle of 65°) unlike previous studies conducted on highly wetting molecularly smooth materials (e.g., glass/silicon). Four fundamentally different topological flow regimes (Capillary Bubbly, Segmented, Annular, Dry) were identified along with two transitory ones (Segmented/Annular, Annular/Dry) and regime boundaries were identified from the two different test chips. The regime transition boundaries were influenced by the geometry of the two-phase injection, the aspect ratio of the test micro-channels, and potentially the chip material as evidenced from comparisons with the results of previous studies. Three principal Segmented flow sub-regimes (1, 2, and 3) were identified on the basis of quantified topological characteristics, each closely correlated with two-phase flow pressure drop trends. Irregularity of the Segmented regimes and related influencing factors were addressed and discussed. The average bubble length associated with the Segmented flows scaled approximately with a power law of the liquid volumetric flow ratio, which depends on aspect ratio, liquid superficial velocity, and the injection system. A simplified semi-empirical geometric model of gas bubble and liquid plug volumes provided good estimates of liquid plug length for most of the segmented regime cases and for all test-channel aspect ratios. The two-phase flow pressure drop was measured for the square test channels. Each Segmented flow sub-regime was associated with different trends in the pressure drop scaled by the viscous scale. These trends were explained in terms of the quantified flow topology (measured gas bubble and liquid plug lengths) and the number of bubble/plug pairs. Significant quantitative differences were found between the two-phase pressure drop in the polymer micro-channels of this study and those obtained from previous glass/silicon micro-channel studies, indicating that the effect of wall surface properties is important. Pressure drop trends on the capillary scale along gas bubbles extracted from the measurements in square micro-channels indicated a linear dependence on the Capillary number and did not agree with those predicted by highly idealized theory primarily because explicit and implicit assumptions in the theory were not relevant to practical conditions in this study.

Seasonal variations in ectotherm growth rates: Quantifying growth as an intermittent non steady state compensatory process

Generally, growth rates of living organisms are considered to be at steady state, varying only under environmental forcing factors. For example, these rates may be described as a function of light for plants or organic food resources for animals and these could be regulated (or not) by temperature or other conditions. But, what are the consequences for an individual's growth (and also for the population growth) if growth rate variations are themselves dynamic and not steady state? For organisms presenting phases of dormancy or long periods of stress, this is a crucial question. A dynamic perspective for quantifying short-term growth was explored using the daily growth record of the scallop Pecten maximus (L.). This species is a good biological model for ectotherm growth because the shell records growth striae daily. Independently, a generic mathematical function representing the dynamics of mean daily growth rate (MDGR) was implemented to simulate a diverse set of growth patterns. Once the function was calibrated with the striae patterns, the growth rate dynamics appeared as a forced damped oscillation during the growth period having a basic periodicity during two transitory phases (mean duration 43 days) and appearing at both growth start and growth end. This phase is most likely due to the internal dynamics of energy transfer within the organism rather than to external forcing factors. After growth restart, the transitory regime represents successive phases of over-growth and regulation. This pattern corresponds to a typical representation of compensatory growth, which from an evolutionary perspective can be interpreted as an adaptive strategy to coping with a fluctuating environment.

Nonisothermal crystallization kinetics of novel biodegradable poly(butylene succinate-co-2-methyl-1,3-propylene succinate)s

Two novel poly(butylene succinate-co-2-methyl-1,3-propylene succinate)s, PBMPSu 95/5 and PBMPSu 90/10, were characterized as having 6.5 and 10.8 mol% 2-methyl-1,3-propylene succinate (MS) units, respectively, by 1H NMR. A differential scanning calorimeter (DSC) and a polarized light microscope (PLM) employed to investigate the nonisothermal crystallization of these copolyesters and poly(butylene succinate) (PBSu). Morphology and the isothermal growth rates of spherulites under PLM experiments at three cooling rates of 1, 2.5 and 5 °C/min were monitored and obtained by curve-fitting. These continuous rate data were analyzed with the Lauritzen-Hoffman equation. A transition of regime II→III was found at 96.2, 83.5, and 77.9 °C for PBSu, PBMPSu 95/05, and PBMPSu 90/10, respectively. DSC exothermic curves at five cooling rates of 1, 2.5, 5, 10 and 20 °C/min show that almost all of the nonisothermal crystallization occurred in regime III. DSC data were analyzed using modified Avrami, Ozawa, Mo, Friedman and Vyazovkin equations. All the results of PLM and DSC measurements reveal that incorporation of minor MS units into PBSu markedly inhibits the crystallization of the resulting polymer.

Modelling of biomass combustion process

Abstract The paper presents a different approach on biomass combustion process modelling based on Bond Graph methodology. The main thermal-chemical processes used for biomass to energy conversion are oxidative. This study focused on oxidation process with heat generation using solid fuels. The important number of biomass categories and different conversion technologies influence the model input parameters in terms of temperatures, mass flows, heat exchange, requiring different models for combustion processes. The large range of biomass based products can be represented by carbon, hydrogen, oxygen, chlorine, sulphur, and nitrogen composition. In order to highlight the modelling method advantages, the research focused on wood biomass combustion. The product was represented by carbon, hydrogen, and oxygen composition given through their molar fraction. The paper presents the results on combustion process kinetics with respect to reactant and reactor input data, especially for the transitory regimes like ignition. The model provides information on time variation of the heat of reaction, reaction products concentration, and reactants concentration / accumulation, based on global mass and energy balance of the process.

Effective mixing in a microfluidic oscillator using an impinging jet on a concave surface

In this study, we present a microfluidic oscillator design that employs an impinging jet on a concave surface to enhance the microscale mixing process. The Coandă effect along with the Gortler instability proves to incite sustainable flapping motion beyond the obstacle and mixing is profoundly improved. From the flow visualization results, four different regimes are identified and we find that the primary enhancement of mixing performance is always linked to the transition of flow regime. Moreover, incorporating a sudden-expansion confluence provokes flow three dimensionality and elevates the mixing level significantly at low Reynolds numbers. For a Reynolds number as low as 70, the tail flow behind the concave obstacle successfully exhibits a periodic oscillation and Hopf bifurcation is induced, leading to a drastic augmentation in the time-average mixing efficiency. By utilizing the spectrum analysis, the characteristic frequency of flapping motion is found to vary linearly with the throat velocity, resulting in a constant Strouhal number of 3.8 × 10−5.

Friction and wear behavior of Cu–CeO 2 nanocomposite coatings synthesized by pulsed electrodeposition

The friction and wear behavior of copper matrix nanocomposites reinforced with nanosized ceria particles, synthesized by pulse electrocodeposition technique, have been investigated. Tests have been carried out under dry sliding conditions by rubbing against a steel ball at varying loads ranging from 4 to 20 N and at constant speed of 11 rpm using a ball-on-disk wear tester. The experimental results indicate that the wear resistance of copper composite is superior to that of pure copper at all the loads and it improves with the increasing amount of ceria in the copper matrix. The friction coefficient and wear rates increase with the increase in applied load. When the load increases from 4 to 20 N, the transition of wear regime from local damage to delamination of a mechanically mixed layer (MML) occurs.

Use of thermal logs to characterize the circulation of fluids: the case of hydrothermal circulations in the Maurienne Valley (Western Alps)

Abstract Over the last 15 years, several dozen deep boreholes (depths in excess of 500 m) have been drilled in the Maurienne Valley as part of the survey work for the new Lyons-Turin rail link. A number of parameters have been logged in these boreholes as a matter of routine, including data on fluids, such as temperature, electrical conductivity and vertical flow velocity. Because several logging campaigns have been carried out in each borehole, it has generally been possible to separate disturbances caused by the drilling (creation of links between water-bearing fractures, establishment of transitory thermal regimes, drilling-related heating, etc.) from the natural initial thermal state. Consequently, most natural thermal state descriptions are based on reconstructions, rather than on raw data. In many cases, in particular in the Houillère Briançonnaise Zone, this natural thermal state is governed by the circulation of hot and cold fluids. We suggest that these two types of circulation actually form a single circuit, in which cold waters infiltrating in the north-south trending Evaporite Zone and in the carbonates of the Sub-Briançonnais Zone flush deep waters so that they rise preferentially along the axis of the valley in the east-west trending Houillère Zone. Focal mechanism data and leveling comparisons show that the front of the Houillère Zone (including the evaporites and the Sub-Briançonnais carbonates), which controls infiltration into the system, is currently subject to WNW-ESE extension. The rising hot waters are controlled by the valley, which is an extensional structure perpendicular to the Houillère Zone. This interpretation is in line with the increased heat flow towards the axis of the valley, and with the occurrence of rising thermal waters further down the valley, for example at Echaillon and Les Chavannes. The interaction between these two extensional systems, which has been observed at least on a regional scale, gives a highly dynamic character to the current deformation, as is shown by the new a-seismic tectonic regime that has affected the region since 1995. Given this dynamic character, it is unlikely that a hydraulic-thermal regime has existed undisturbed for more than 15,000 years. The example described in the present article shows how the repeated logging of thermal data in boreholes over a period of time can help delineate deep circulations. Combined with detailed information about the current deformation regime, this logging data allows a detailed picture of circulation patterns to be drawn.

Nonisothermal crystallization kinetics of biodegradable poly(butylene succinate‐co‐propylene succinate)s

AbstractPoly(butylene succinate) (PBSu) and two poly(butylene succinate‐co‐propylene succinate)s were synthesized via the direct polycondensation reaction. The copolyesters were characterized as having 7.0.and 11.5 mol % propylene succinate (PS) units, respectively, by 1H NMR. A differential scanning calorimeter (DSC) and a polarized light microscope (PLM) adopted to study the nonisothermal crystallization of these polyesters at a cooling rate of 1, 2, 3, 5, 6, and 10 °C/min. Morphology and the isothermal growth rates of spherulites under PLM experiments were monitored and obtained by curve‐fitting. These continuous rate data were analyzed with the Lauritzen−Hoffman equation. A transition of regime II → III was found at 95.6, 84.4, and 77.3 °C for PBSu, PBPSu 95/5, and PBPSu 90/10, respectively. DSC exothermic curves show that all of the nonisothermal crystallization occurred in regime III. DSC data were analyzed using modified Avrami, Ozawa, Mo, Friedman, and Vyazovkin equations. All the results of PLM and DSC measurements indicate that incorporation of minor PS units into PBSu markedly inhibits the crystallization of the resulting polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1299–1308, 2010

Time Evolution of Optical Emission Spectrum of a Hg-HID Lamp Exposed to X-ray

Time variation of optical emission lines for Hg, and other elements detected in a mercury HID lamp before and during X-ray irradiation were analyzed. Various irradiation conditions are causing differences in time dependencies of all Hg spectral line intensities (including that of 253.73 nm resonance line not completely self-absorbed). The X-ray optical depths are smaller in the case of Hg gas compared with burner wall glass. The free electrons generated during X-ray exposure (photoelectrons, Auger electrons) contribute to changes in plasma characteristics (e.g. plasma temperature, density, etc.) in transitory regime. In quasi-stable regime there are practically no differences between electron temperatures for normal and irradiated lamp. A qualitative explanation in the framework of Beer-Lambert law is given.

Crystal growth rates and master curves of poly(ethylene succinate) and its copolyesters using a nonisothermal method

AbstractThe spherulitic growth of poly(ethylene succinate) (PES) and two PES‐rich copolyesters at constant cooling rate was monitored and recorded using a system of polarized light microscope. Individual experiment of these polyesters lasted 40, 60, and 120 min, respectively. A continuous curve of isothermal growth rates between the melting and glass transition temperatures can be obtained after curve fitting procedures. These curves fit very well with those data points determined in the isothermal experiments, which are time consuming. The continuous data of PES was analyzed with the Hoffman (Lauritzen equation. A transition of regime II → III was found at 70.7 °C, which is very close to the literature values. The maximum growth rate was formulated in the Arrhenius and WLF expressions for the molecular transport term. A master curve of crystal growth rate for PES was constructed based on the continuous data of PES. When the reduced growth rates after normalization were plotted against the reduced temperatures, a universal master curve was observed for PES and two PES‐rich copolyesters. This nonisothermal method provides an efficient and reliable way for studying the crystallization kinetics of polymer and for constructing a universal master curve of crystal growth rate of PES. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 932–939, 2010

Behavior of a methanol fuel cell in transitory regime

The operation of a polymeric electrolyte methanol/air fuel cell connected to a storage tank with anolyte batch recycle is analyzed. When the cell is discharged at constant current, far below the anode reaction limiting current density, the concentration in the tank is found to decrease with time following a lineal variation. At zero time, a high CO 2 concentration is detected in the air leaving the cathode compartment, which increased when higher methanol concentration is used in the anode compartment. This effect is associated to the crossover of methanol through the membrane. The amount of CO 2 in the air outlet is important, and both this quantity and the crossover flux decrease when methanol concentration diminish in the anolyte. A model derived from electrochemical reactor analysis, that correlates methanol concentration changes in the storage tank, and methanol concentration at the anodic compartment exit with the amount consumed in the cell reaction and the flow through the membrane is developed.

Different stages of flame acceleration from slow burning to Chapman-Jouguet deflagration

Numerical simulations of spontaneous flame acceleration are performed within the problem of flame transition to detonation in two-dimensional channels. The acceleration is studied in the extremely wide range of flame front velocity changing by 3 orders of magnitude during the process. Flame accelerates from realistically small initial velocity (with Mach number about 10(-3)) to supersonic speed in the reference frame of the tube walls. It is shown that flame acceleration undergoes three distinctive stages: (1) initial exponential acceleration in the quasi-isobaric regime, (2) almost linear increase in the flame speed to supersonic values, and (3) saturation to a stationary high-speed deflagration velocity. The saturation velocity of deflagration may be correlated with the Chapman-Jouguet deflagration speed. The acceleration develops according to the Shelkin mechanism. Results on the exponential flame acceleration agree well with previous theoretical and numerical studies. The saturation velocity is in line with previous experimental results. Transition of flame acceleration regime from the exponential to the linear one, and then to the constant velocity, happens because of gas compression both ahead and behind the flame front.

Road runoff management using over-the-shoulder infiltration: real-scale experimentation

A new management policy regarding road runoff was proposed in 2002 by the Swiss Federal Office for the Environment (FOEN). This new concept is based on the diffuse infiltration of road runoff into embankment slopes, where soils will filter particles and contaminants. The shoulder lying between road surface and infiltration slopes must be impervious in order to maximise the amount of water reaching the slope and avoid losses in the road structure. The implementation of this new concept should lower the impact of roads on the environment, improve aquifer recharge and reduce construction costs. The Swiss Federal Road Office (FedRO) decided to carry out real-scale investigations regarding this new policy and thus commissioned the GEOLEP to design, build, and test 5 different shoulder structures. This paper presents the results of a 2-years survey of infiltration processes in these shoulders to establish the best performing structure. The first three shoulders were overlaid with 5 cm of gravel mixed with humus, gravel mixed with clay, and seeded with lawn, respectively. The latter two had impervious layers located 26 cm deep: the road bituminous basement (road base) was prolonged and coated with bitumen in the first case, and a sodic-bentonite geotextile was used in the second. Both were covered with gravel. All shoulders were equipped with basal collecting devices that measured hydraulic fluxes seeping through the shoulders. In total, 112 natural precipitations and 3 artificial events were monitored. Artificial events mimicked known transitory regimes (thunderstorms) or were performed with constant regime. The goal was to effectively assess infiltration processes in shoulders. Results showed that shoulders made of gravel and humus or lawn were highly ineffective (only 30 to 40% of runoff is conducted to the infiltration slope). Gravel and clay was more efficient with a proportion of approximately 60%. The shoulder with prolonged road base showed similar results since the bituminous coating was in fact rather permeable. The best results were exhibited by the shoulder waterproofed with bentonitic geotextile, which allowed no water to penetrate. This material already proved to be very powerful in groundwater catchments. The authors thus proposed a combination of sodic-bentonite geotextile covered by a gravel and clay mixture. This would be the most efficient shoulder: it will convey all the runoff to infiltration slopes, thereby optimising its filtration, which in turn will enhance environmental conditions in the vicinity of roads.

The turning point on plots of log ϕ and log t of Mo's equation

AbstractBACKGROUND: Mo's equation based on the Avrami equation and Ozawa equation has been successfully used in non‐isothermal crystallization kinetics by many researchers. However, in recent years we have found that plots of log ϕ–log t of Mo's equation are not straight lines, but there appears a turning point at ϕ = 7 °C min−1 or so. The aim of this article is to analyze in detail the reason for the occurrence of this turning point by studying the non‐isothermal crystallization of poly(vinylidene fluoride) (PVDF) using differential scanning calorimetry.RESULTS: A turning point at about 7 °C min−1 appeared on plots of log ϕ–log t. The cooling rate where the turning point occurred showed little change with increasing relative crystallinity, but the temperature decreased. It is noted that this turning‐point temperature is lower than transition temperature of regime I → II reported for PVDF.CONCLUSION: We deemed that the occurrence of turning points on plots of log ϕ–log t of Mo's equation can be ascribed to the different crystallization regimes based on the Hoffman nucleation theory, and presumed that the turning point corresponded to transition of regime I → II. Finally, we considered that Mo's equation should be analyzed using two beelines, instead of one beeline. Copyright © 2009 Society of Chemical Industry

Analysis of an automobile assembly line as a network of closed loops working in both, stationary and transitory regimes

In this work a real automobile assembly line and the correspondent preassembly lines have been analyzed as a network of closed loops of machines decoupled by intermediate buffers. This work deals with some important aspects, which have still not been investigated in earlier literature, such as: machines processing pallets, which are not related to each other and depend on an external variable in a network with closed loops of machines and intermediate buffers, machines working at different cycle times in a network of closed loops of machines and intermediate buffers, machines working in both, stationary and transitory regime and the relationships between the cycle times of the machines in the stationary working regime in order to guarantee the production rate of the system. Finally how the transient results can be used to improve the performance of the system under certain working conditions is discussed.

Phase diagram of the Holstein polaron in one dimension

The behavior of the 1D Holstein polaron is described, with emphasis on lattice coarsening effects, by distinguishing between adiabatic and nonadiabatic contributions to the local correlations and dispersion properties. The original and unifying systematization of the crossovers between the different polaron behaviors, usually considered in the literature, is obtained in terms of quantum to classical, weak coupling to strong coupling, adiabatic to nonadiabatic, itinerant to self-trapped polarons and large to small polarons. It is argued that the relationship between various aspects of polaron states can be specified by five regimes: the weak-coupling regime, the regime of large adiabatic polarons, the regime of small adiabatic polarons, the regime of small nonadiabatic (Lang-Firsov) polarons, and the transitory regime of small pinned polarons for which the adiabatic and nonadiabatic contributions are inextricably mixed in the polaron dispersion properties. The crossovers between these five regimes are positioned in the parameter space of the Holstein Hamiltonian.

Attractor Landscapes and Active Tracking: The Neurodynamics of Embodied Action

Behavior is the product of three intertwining dynamics: of the world, of the body and of internal control structures. Neurodynamics focuses on the dynamics of neural control, while observing interfaces with the world and the body. From this perspective, we present a dynamical analysis of embodied recurrent neural networks evolved to control a cybernetic device that solves a problem in active tracking. For competent action selection, agents must rely on the attractor landscapes of the evolved networks. Insights into how the networks achieve this are given in terms of the network's dynamical substrate, which highlights the role of the network's inherent attractors as they change as a function of the input parameters (sensors). We introduce some terminological extensions to neurodynamics to allow for a more precise formulation of how attractor changes influence behavior generation: in particular, attractor landscapes, which are the space of all attractors accessible through coherent parametrizations of the network (input stimuli), and the meta-transient, which resolves behavior by approaching attractors as they shape-shift. We apply these concepts to the analysis of interesting behaviors of the tracking device, such as temporal contextual dependency, chaotic transitory regimes in moments of ambiguity, and implicit mapping of environmental asymmetricities in the response of the device. Finally, we discuss the relevance of the concepts introduced in terms of autonomy, learning, and modularity.

Real-time monitoring of SiO 2/Si(1 1 1) interlayer etching by Brewster-angle reflectometry

A transitory etching regime after SiO 2 dissolution and before bulk Si(1 1 1) etching in neutral NH 4F solutions was monitored by in situ Brewster-angle reflectometry (BAR). An observed intermediate increase of the BAR reflectance signal is attributed to a fast dissolution of a stressed/strained interlayer beneath the SiO 2/Si(1 1 1) interface. Similar effects were observed on thin thermal oxides (18.2 nm), grown on float zone silicon, as well as on ultra-thin native oxides (1.2 nm) on Czochralsky silicon. Native oxide covered samples showed an increased surface roughness in the course of interlayer dissolution while the surface is progressively covered with compounds of fluorinated silicon. The etch rate, determined by atomic force microscopy (AFM) and compared to the etch rate of bulk silicon, is increased by a factor of four. In the limit of extended etching, the known low etch rates for silicon in 40% NH 4F are observed. Structural and chemical properties of the interfacial layer were analyzed by synchrotron radiation photoelectron spectroscopy (SRPES) which confirmed the presence of Si 3+/4+ valence states throughout the interlayer and by near open-circuit potential (N-OCP) dark current measurements. As a result, oxide etch rates in NH 4F in the pH-range ∼7–8 as well as the silicon interlayer depth can be assessed by in situ BAR.

Susceptibility to LME of 316L and T91 steels by LBE: Effect of strain rate

The effect of liquid lead–bismuth eutectic on 316L and T91 steels at 160 °C has been studied as a function of strain rate, using a centre cracked in tension specimen adapted for the study of crack propagation. Brittle fracture, characterized by elongated river cracks on all the fracture surfaces, indicates that T91 is sensitive to the embrittlement by LBE. This embrittlement effect is very pronounced at low deformation rate (∼10 −5 mm s −1). A ductile–brittle transition is observed in the high strain rate range investigated. In the transitory regime, there is a competition between the growth of dimples and brittle cracking induced by the liquid metal. Ductility recovery is complete at the highest investigated deformation rate. The mechanical properties of the 316L steel are not clearly affected by the presence of LBE, in spite of a modification in the plastic deformation mode which strongly affects fracture surfaces.