Uniform Regime Research Articles

Breakup of compound liquid jets under periodic excitation at small core‐to‐shell mass ratios

A periodic excitation was applied to a compound liquid jet, which was composed of a core liquid, water, surrounded by a shell liquid, diesel oil, for an experimental investigation on its breakup. The core‐to‐shell mass ratio, γ, and the ratio of disturbance wavelength to undisturbed diameter of the compound jet, λ/D, were taken into consideration as parameters to describe the breakup processes of the compound jet. For γ < 0.36, the compound jet breakup was classified into six patterns. By comparing the breakup of a single diesel jet to that of a water‐in‐diesel compound jet, two conclusions were drawn. First, the uniform drop regime of the compound jet was wider than that of the single jet. Second, both the single jet and water‐in‐diesel compound jet broke randomly in the range of λ/D ≤ 3.

Initiation of granular surface flows in a narrow channel

We experimentally investigate how a long granular pile confined in a narrow channel destabilizes when it is inclined above the angle of repose. A uniform flow then develops, which is localized at the free surface. It first accelerates before reaching a steady uniform regime. During this process, an apparent erosion is observed and the thickness of the flowing layer increases. We precisely study the evolution of the vertical velocity profile in this transient regime. The measurements are compared with the prediction of a viscoplastic model [Jop et al., Nature 441, 727 (2006)].

International R&amp;D Rivalry with Spillovers and Tariff Policies

This paper investigates the effects of R&D spillovers on the R&D choices of foreign exporters when the importing country adopts either uniform or discriminatory alternative tariff regimes. We show that the importing country should optimally choose a uniform tariff regime. A uniform tariff regime is also advantageous for foreign exporters if the R&D spillovers are sufficiently large. A comparison of free trade with the two tariff regimes reveals that there are some situations in which both the importing country and foreign exporters are better off under free trade, which supports trade liberalization.

Effect of competition between particle–particle and gas–particle interactions on flow patterns in dense gas-fluidized beds

Particle–particle (P–P) and particle–fluid (P–F) interactions are two fundamental phenomena in dense particulate flows which interact mutually to compose a variety of flow structures. Using discrete particle simulation and energy budget analysis, we quantitatively explore the effect of competition between these interactions on flow patterns in dense gas-fluidized beds. A diagram, picturing flow pattern formation and its evolution, along with the altering roles of P–P collision and P–F interaction in their competition, is presented and detailed energy analysis is used to explore how P–P collision and P–F interaction drives flow pattern formation and transition. It is shown that the flow structures in various flow regimes, ranging from the fixed to the turbulent regime, can be reproduced from these simulations. Systems with strong collisional dissipation but weak gas–particle interaction display a distinct emulsion–bubble two-phase flow structure. On the contrary, systems with strong gas–particle interaction but less pronounced collisional dissipation produce uniform structures, as often observed in the uniform regime near the incipient fluidization point. If these two interactions are equally important, the system features complex flow patterns resembling those displayed in the turbulent fluidization regime. Energy analysis demonstrates that the competition between P–P collision and P–F interaction determines flow structure formation and its evolution. The flow regime transition is actually the macro-scale expression of the altering of degree of dominance of P–P and P–F interactions.

Position dependence of growth rate in convection enhanced laser CVD of carbon rods

The ability to closely monitor LCVD rod growth in the growth region is demonstrated in the context of the first open-air axial convection enhanced micro-reactor. It was used to monitor carbon rod growth inside coaxial cylindrical flows of ethylene and argon. Monitoring and subsequent image analysis of the 656 nm atomic hydrogen emission from ethylene pyrolysis allowed real-time in-situ determination of axial growth rate and diameter along the axis of the produced carbon rods for the first time. Growth rates appear to vary greatly inside the growth region. This experiment raises questions about published qualitative models of LCVD rod growth that favor a uniform steady state regime. If the trend demonstrated in our experiments is not just an artifact of flow mixing, then it would indicate that published registered growth rates may just be an average value or an artifact of focus tracking. The results, therefore, point the way to experiments that would allow discrimination between the effect of flow mixing and the true nature of LCVD rod growth in the growth region.

The jury and the law of evidence: real and imagined interconnections

Among both legal practitioners and legal scholars, the view prevails that Anglo-American rules of evidence should be relaxed in trials where judges sit alone. The most frequently invoked reason for this view is that Anglo-American rules of evidence are called forth because of the cognitive weaknesses of lay adjudicators. Professional judges are supposed to be free of these weaknesses so that in juryless trials, much of the law of evidence loses its raison d'etre. However, since modern research has shown that professional and amateur adjudicators are both prone to over- or underestimate certain classes of information, the view has emerged that a uniform evidentiary regime is mandated for both lay and professional adjudicators. Both classes of adjudicators should be bound by strict rules of evidence. The article questions the wisdom of the uniform fact-finding regime. The main reason for scepticism is the difference in the institutional context of jury and juryless trials. When judges sit without the jury, they must decide not only on the admissibility of evidence but also on the ultimate disposition of the case. Thus, if an inadmissible item of information appears to them as persuasive, they are expected to switch to a third person's viewpoint and attempt to arrive at a decision by hypothesizing what outcome another adjudicator would reach who was uncontaminated by the forbidden information. In the author's opinion, the demand for such an impersonal mode of decision making is on several grounds undesirable. The author is also critical of the view that juryless systems failed to develop a comprehensive law of evidence. He argues that there are many sources of complex evidentiary arrangements, besides those related to lay participation in the administration of justice. As far as the European continent is concerned, this is best exemplified by the juryless Roman-canon procedure of the ancien regime, which developed a very comprehensive law of proof. Moreover, contrary to what is often believed by lawyers in the common law world, even contemporary continental procedures, dominated by professional judges, tend to generate a lot of evidence law although this law is for several reasons not clear in view of outside observers.

Estimating Demand for Differentiated Products with Continuous Choice and Variety-Seeking: An Application to the Puzzle of Uniform Pricing

Retailers typically sell many different products from the same manufacturer at the same price. I consider retailer-based explanations for this uniform pricing puzzle, estimating the counterfactual profits that would be lost by a retailer switching from a non-uniform to a uniform pricing regime in the carbonated soft drink category. In order to calculate this profit difference, I develop a new structural model of demand that improves on existing work by more closely matching several key features of the data. These key features include the fact that households may be variety-seeking, that they make continuous choices, and that they choose from a large number of products. Using household-level panel data on purchases of carbonated soft drinks, I estimate that the retail store I observe earned an additional $36.56 (1992 dollars) in average weekly profits by charging non-uniform prices. This corresponds to roughly a 3% difference in profits, and suggests that when a retail store faces even a relatively small cost to determine the optimal set of non-uniform prices, it may be optimal to charge the same price for many products.

Different Flavor, Same Price: The Puzzle of Uniform Pricing for Differentiated Products

Retailers typically sell many different products from the same manufacturer at the same price. I consider managerial menu costs as an explanation for this uniform pricing puzzle, using a structural model to estimate the counterfactual profits that would be lost by a retailer switching from a non-uniform to a uniform pricing regime in the carbonated soft drink category. The results suggest that when a retail store faces even a relatively small cost to determine optimal non-uniform prices, it may be optimal to charge the same price for many products.

Geomagnetic field variations between chrons 33r and 19r (83–41 Ma) from sea-surface magnetic anomaly profiles

Sea-surface magnetic profiles exhibit coherent short wavelength “micro-anomalies” (or “tiny wiggles”) superimposed to the main anomalies due to reversals. In this study, we investigate the nature and distribution of these tiny wiggles on oceanic crust formed during the ∼ 42 Myr-long period following the Cretaceous Normal Superchron. To this end, we compute stacks of anomaly profiles from different areas in the Indian and the Pacific oceans. Using a simple method based on upward continuation, we demonstrate that, the tiny wiggles are consistent worldwide although their patterns exhibit different resolutions at different spreading rates. They are therefore confidently ascribed to past fluctuations of the geomagnetic dipole moment. A high resolution record of these fluctuations is obtained by selecting and stacking profiles from areas with the highest spreading rates. Modeling the micro-anomalies as short magnetic polarity intervals yields durations for these intervals generally shorter than 10 kyr, likely too short to be indeed “true” subchrons. Moreover, the number of detected tiny wiggles clearly depends on the spreading rate. These results support geomagnetic intensity fluctuations as being the cause of most tiny wiggles, as also suggested by recent magnetostratigraphic data. The tiny wiggles are uniformly distributed within chrons, indicating that paleointensity fluctuations are neither inhibited after, nor enhanced before, a reversal beyond a “blind” zone of about 10 km (corresponding to 80 to 250 kyr depending on the spreading rate) for which the anomalies due to reversals prevent the detection of tiny wiggles. Most tiny wiggles probably represent a filtered record of a uniform secular variation regime, as suggested by their uniform spatial distribution over the whole investigated period.

International financial reporting standards and experts’ perceptions of disclosure quality

From 2005, over 7,000 listed firms in the European Union and many more around the world are required to adopt International Financial Reporting Standards (IFRS). The introduction of a uniform accounting regime is expected to ensure greater comparability and transparency of financial reporting around the world. However, recent research has questioned the quality of financial statements prepared under IFRS standards, particularly in the presence of weak enforcement mechanisms and adverse reporting incentives (Ball et al., 2003). In this paper, we assess the quality of the financial statements of Austrian, German and Swiss firms which have already adopted internationally recognized standards (IFRS or U.S. GAAP). The study makes use of available disclosure quality scores extracted from detailed analyses of annual reports by reputed accounting scholars (‘experts’). This work complements other contemporary research on the quality of IFRS financial statements where the properties of earnings are used as an evaluation metric (Barth et al., 2005). Our evidence shows that disclosure quality has increased significantly under IFRS in the three European countries we analyse. This result holds not only for firms which have voluntarily adopted IFRS or U.S. GAAP, but also for firms which mandatorily adopted such standards in response to the requirements of specific stock market segments. Although we cannot establish direct causality due to the inherent self‐selection issues for most of our sample firms, the evidence shows that the quality of financial reports has increased significantly with the adoption of IFRS.

THE ELASTICITY OF CAPITAL–LAND SUBSTITUTION IN THE HOUSING CONSTRUCTION SECTOR OF A RAPIDLY URBANIZED CITY: EVIDENCE FROM TURKEY

This paper estimates the elasticity of capital‐land substitution for the housing market in Ankara, the capital city of Turkey. Using constant elasticity of substitution (CES) and variable elasticity of substitution (VES) production functions and cross‐section data, the paper provides new information to compare the housing supply elasticity of Ankara with that of the USA and the UK cases. Our regression results reveal that housing supply in Ankara is highly inelastic due to the uniform construction regime of local authorities. Moreover, we find that there is a considerable spatial differentiation of urban land density measures within the capital city. Because of the incomplete urbanization process, the elasticity of capital‐land substitution is significantly higher in the outer parts of the city.

Simulations of ultracold bosonic atoms in optical lattices with anharmonic traps

We report results of quantum Monte Carlo simulations in the canonical and the grand-canonical ensemble of the two- and three-dimensional Bose-Hubbard model with quadratic and quartic confining potentials. The quantum criticality of the superfluid-Mott insulator transition is investigated both on the boundary layer separating the two coexisting phases and at the center of the traps where the Mott-insulating phase is first established. Recent simulations of systems in quadratic traps have shown that the transition is not in the critical regime due to the finite gradient of the confining potential and that critical fluctuations are suppressed. In addition, it has been shown that quantum critical behavior is recovered in flat confining potentials as they approach the uniform regime. Our results show that quartic traps display a behavior similar to quadratic ones, yet locally at the center of the traps the bulk transition has enhanced critical fluctuations in comparison to the quadratic case. Therefore quartic traps provide a better prerequisite for the experimental observation of true quantum criticality of ultracold bosonic atoms in optical lattices.

Analysis and measurements of mixing in pressure-driven microchannel flow

The mixing phenomena for two fluid streams in pressure-driven rectangular microchannels are analyzed and directly compared with the measurements of mixing intensity for a wide range of aspect ratio (width/depth = 1–20). In the analysis, the three-dimensional transport equation for species mixing was solved using the spectral method in a dimensionless fashion covering a large regime of the normalized downstream distance. The analysis reveals the details of non-uniform mixing process, which originates from the top and bottom walls of the channel and stretches out toward the center of the channel, and its transition to uniformity. Employing different length scales for the non-uniform and uniform mixing regimes, the growth of mixing intensity can be expressed in a simple relationship for various aspect ratios in the large range. The mixing experiments were carried out on silicon- and poly(methyl methacrylate) (PMMA)-based T-type micromixers utilizing fluids of pH indicator (in silicon channel) and fluorescent dye (in PMMA channel) to evaluate the mixing intensity based on flow visualization images. Using conventional microscopes, the experiments demonstrate the mixing intensity as a power law of the stream velocity for all the microfluidic channels tested. The variations of measured mixing intensity with the normalized downstream distance are found in favorable agreement with the numerical simulations. The comparison between the experiments and simulations tells the capabilities and limitations on the use of conventional microscopes to measure the mixing performance.

Uniform versus Discriminatory Tariffs: When Will Export Taxes Be Used?

1. IntroductionThis paper attempts to combine two branches of strategic trade policy literature together by analyzing choices of export subsidies and import taxes in a unified framework. It aims to provide a better insight into the interactions among the governments of two exporting countries and an importing country.In a seminal paper, Brander and Spencer (1985) show that under Cournot competition a domestic export subsidy allows a domestic firm to gain at the expense of a rival firm in another exporting country. Their paper initiated a great deal of interest in the proper use of export subsidies.1 It is noted that in the Brander-Spencer and related models, the government of the third country, which imports the goods from the two countries, is assumed to be inactive. On the other hand, there is a separate literature that analyzes the optimal policies for an importing country, which buys a homogeneous product from two countries with rival firms. For example, Gatsios (1990) and Hwang and Mai (1991) show that the optimal policy for the importing country is to impose a higher tariff on the product from the more cost-efficient exporter. Choi (1995) and Horiba and Tsutsui (2000) extend the literature by comparing the impacts of discriminatory and uniform tariffs. Both of these two papers examine the choice of the two tariff regimes by the importing country, and investigate how a regime may affect the level of technologies chosen by the exporting firms. All these papers focus on the policies of the importing country, while assuming that the exporting governments are inactive.In this paper, we consider a model similar to those examined by all these papers: two exporting countries and one importing country, with one firm in each of the exporting countries competing in a Cournot way. What makes the present paper different from others is that we allow all three governments to be active in choosing the optimal values of their policies: an export subsidy/tax for each exporting country and a tariff/subsidy for the importing country. We also analyze the impacts of two different tariff regimes: a uniform tariff regime, as required by the Most-Favored-Nations (MFN) clause of the GATT/WTO, and a discriminatory tariff regime. Choosing between these two types of tariff regimes is an interesting issue in the present framework, because it not only determines the welfare of the importing country, but also affects the export subsidies chosen by the exporting countries. The present, more extensive model and analysis, as compared with what exists in the literature, can be used to answer several questions. If each exporting country is aware of the tariffs to be imposed by the importing country on the products from itself and its rival, does it still have an incentive to impose an export subsidy, as Brander and Spencer proposed? Does such an export subsidy depend on whether the importing country is using discriminatory tariffs or a uniform tariff? How might the noncooperative equilibrium in terms of export subsidies be affected by the tariff regimes chosen by the importing country? What is the optimal tariff of the importing country in response to the export subsidies chosen by the exporting countries? How would the importing country choose between the two tariff regimes? How would the welfare of these countries be affected by the policies and the policy regimes?Some of the results obtained in the present paper can be linked to the existing results. Under a uniform tariff regime, as required by the MFN clause, the Brander-Spencer argument kicks in, and each country has the right incentive to promote the export of its own firm with an export subsidy. If the importing country is using discriminatory tariffs, the argument in the papers by Gatsios (1990), Hwang and Mai (1991), Choi (1995), and Horiba and Tsutsui (2000) is applicable: An importing country tends to impose a higher tariff on the more cost-efficient exporter. …

International regulation of liability for multimodal transport

The establishment of a widely acceptable uniform international legal framework for multimodal transport has proven to be extremely difficult. In spite of attempts by various international organizations, following the advent of container revolution, there is still no uniform international legal regime in force to govern liability for loss, damage or delay arising from multimodal transportation. In 2002 the United Nations Commission on International Trade Law (UNCITRAL) embarked on the elaboration of a draft instrument to cover contracts for the international carriage of goods. The Draft Instrument, which had been prepared to govern sea transport, is proposed also to cover multimodal transport involving a sea leg.

Uniform versus Discriminatory Tariffs: When Will Export Taxes Be Used?

This paper examines the noncooperative interactions between two exporting countries and one importing country when all of them are seeking the optimal policies to improve their welfare. Whereas the importing country has the incentive to impose tariffs on the goods coming from the two exporting countries, the export policies chosen by the exporting countries depend on the tariff regime, whether uniform or discriminatory tariffs are used. It is argued that export taxes are chosen by both exporting countries in some cases, and that whereas the importing country prefers a uniform tariff regime, the exporting countries find a discriminatory tariff regime preferable.

ON THIRD-DEGREE PRICE DISCRIMINATION IN OLIGOPOLY*

In this paper we analyse the effects of third-degree price discrimination on output, profit and welfare in a symmetric cost duopoly. We provide sufficient conditions for output, profit and welfare to be higher (or lower) under third-degree price discrimination in a duopoly, compared with a uniform price regime. Comparing our findings with the traditional results on monopoly price discrimination, we show that the output and profit effects under duopoly price discrimination are very different from those under the monopoly case. However, the welfare effects are very similar.

Primary Alkaline Battery Cathodes: A Simplified Model for Porous Manganese Oxide Particle Discharge

A mathematical model for the galvanostatic discharge of a porous manganese oxide particle, similar to those found within primary alkaline battery cathodes, is presented. Asymptotic techniques are employed to obtain the leading order spatial and temporal behavior of the particle. It is found that there is an initial rapid transient adjustment within the crystals forming the particle followed by a prolonged relatively uniform discharge regime which leads finally to a faster, particle-based, nonuniform discharge behavior. Analytical solutions of the model are obtained which describe the majority of the particle behaviors under a wide range of industrially relevant discharge conditions. These solutions are supplemented by simple numerical solutions where required. A comparison of the results with those obtained by a previous, more complete and accurate model is presented. The analysis shows that the particle radius, the applied discharge current, and the solid phase conductivity are the critical parameters that dictate the utilization of active material across a wide range of discharge conditions. The effect of these parameters on particle utilization is also presented.

Rheology of dense granular materials: steady, uniform flow and the avalancheregime

In the first part we present experimental results concerning the flow of a densely packedgrain collection down a two-dimensional inclined channel. For the range of inclinationscorresponding to a steady, uniform regime and to nonsliding conditions at the bottom, weobtain quasi-linear profiles of velocity, that are in contradiction with the predictions of thekinetic theory. We attribute this discrepancy to the inadequacy of the binarycollision picture in the case of dense packings. We also show that the variousvelocity profiles obtained for different flow rates and slopes merge onto a singlemaster curve, according to the following law: (d being the graindiameter, θ the channelinclination angle and θc the maximal angle of repose), provided that the regime is steady and uniform. Arguingthat continuous paths of transient contacts are effective for transporting momentum andenergy through the bulk, and that the associated dissipation time is very short compared tothe time associated with shearing, we succeed in explaining this scaling behaviour and theparadoxical nonzero shear rate in the vicinity of the free surface. We also show thatfor dense particulate flows, the dissipation is mainly due to frictional sliding.In the second part, we emphasize some remarkable features exhibited by dry grainavalanches in laboratory experiments. According to the slope angle, the rear frontpropagates either upwards or downwards, with velocity approximately equal to thedepth averaged velocity of the avalanche. As a counterpart, in both regimes, thevelocity magnitude of the head front remains of the order of twice the depthaveraged avalanche velocity. We suggest simple elementary mechanisms capable ofaccounting for these observations. We propose then an analytical modelling aimed atdescribing the combined processes governing the avalanche expansion. The twosolutions that we obtain for the growth regimes and for the avalanche shapesresemble very closely the observations made in the laboratory and in the field.

Selective oxidation of alcohols in a continuous multifunctional reactor: Ruthenium oxide catalysed oxidation of benzyl alcohol

A multifunctional compact reactor was designed, built, and tested, using as a model reaction the selective oxidation of benzyl alcohol to benzaldehyde with molecular oxygen. The reactor contains static mixers, heat-transfer channels and mm-scale packed-bed reaction channels, i.e., integrating mixing, heat transfer and reaction functionalities. Integrated compact reactor technology should be particularly attractive to the fine chemistry and pharmaceutical industries. The reactor was shown to operate in the kinetic regime over a broad range of operating conditions due to intensified mass transfer. The reactor was also shown to operate isothermally despite high reaction rate, an appreciable heat effect and high reactant concentration (TOF = 300 h −1, Δ H r ° = − 183.7 kJ mo l − 1 ). Staged injection of oxygen along the length of the reactor was investigated as a method of increasing the selectivity of oxidation reactions. Staged injection was shown to be beneficial; however, this was likely to be due to the development of a more uniform hydrodynamic regime of two-phase flow along the packed reaction channel. Experiments were performed with the ruthenium(III) hydrated oxide catalyst supported on alumina (0.9 wt% Ru/Al 2O 3). High activity and selectivity were observed even when working with reactant concentrations approaching industrial conditions (1 mol L −1).