Equilibrium Displacement Research Articles

Analyses on docking dynamic characteristics of the jack-up platform with two-piece units guide cable

Abstract To meet the requirements of deeper offshore oil and gas exploration, a two-piece units mode jack-up rig is employed to upgrade the existing cylindrical leg jack-up rig which works in shallow areas of 50 m deep. A set of mat support structure is added to the bottom of the cylindrical leg jack-up rig and the upper piece of rig and the bottom piece of rig are connected by a docking assembly, making the two pieces become a mat jack-up rig. This paper studies the equilibrium position and displacement response of the upper unit in docking procedure under different environmental condition and different ballast mode based on the three dimensional time domain linear potential flow theory and Morison theory, and analyses the dynamic response of the guide cable under different docking positions through physical models in laboratory. If the environment load acts from the stem direction, longitudinal oscillation affects mostly on the displacement of the guide cable. With the increment of water depth, the axial tension of the guide cable and the vertical angle of deviation decreases. Under the condition of separately floating, the guide cable is mostly affected by the mass of the platform; the forces acting on the guide cable of the lower unit is much smaller than that of the upper unit. Once one of the units was fixed, the towing force dropped obviously. The bearing force of the guide cable is obviously affected by the wave period and wave height and will increase with the increment of wave period and wave height in general.

Price transmission market power and industry technology: a note

PurposeThe purpose of this paper is to develop a theoretical model of price transmission from the farm to the retail sector, allowing not only for an interaction between oligopoly power, oligopsony power and non‐constant returns to scale in industry technology, but also allowing for the market power conduct parameters to vary in response to an industry‐wide exogenous shock. Also, the degree of price transmission under imperfect competition relative to that under perfect competition is evaluated.Design/methodology/approachConjectural variations are used to parameterize both seller and buyer market power conduct of the industry and then the equilibrium displacement approach is applied to solve a system of six structural equations which describe the demand for and supply of industry retail output and farm and marketing inputs.FindingsFirst, it is found that given empirical values of retail output demand elasticity, of farm and marketing inputs supply elasticities, of market power conducts, and of the returns to scale measure, the degree of price transmission under imperfect competition is greater than that under perfect competition. Second, it is found that the relative degree of price transmission under imperfect competition could be greater or smaller under the assumption of a varying market power conduct than one under the alternative assumption of a constant market power conduct, depending on whether market conduct is falling or rising, respectively.Originality/valueThe paper makes two original contributions to the literature. First, it allows for an interaction between oligopoly power, oligopsony power and industry technology. Second, it allows both oligopoly and oligopsony power parameters to vary in response to industry‐wide exogenous shocks.

A Market-based Mitigation Program for Wind-borne Diseases

Wind-borne diseases can spread rapidly and cause large losses. Producers may have little incentive to prevent disease spread because prevention may not be welfare-maximizing. This study proposes a market-based mitigation program that indemnifies producers against disease-related losses and provides an incentive to neighboring producers to take preventive action, which can substantially mitigate infestations, reduce the likelihood of catastrophic losses, and increase social welfare. An equilibrium displacement model simulates introduction of the program for U.S. soybeans. Simulations reveal that the market-based solution contributes to minor market distortions but also reduces social welfare losses and could succeed for other at-risk commodities.

A stabilized finite element method for certified solution with bounds in static and frequency analyses of piezoelectric structures

This paper develops a stabilization procedure in piezoelectric media to ensure the temporal stability of node-based smoothed finite element method (NS-FEM), and applies it to obtain certified solution with bounds in both static and frequency analyses of piezoelectric structures using three-node triangular elements. For such stabilized NS-FEM, two stabilization terms corresponding to squared-residuals of two equilibrium equations, i.e., mechanical stress equilibrium and electric displacement equilibrium, are added into the smoothed potential energy functional of the original NS-FEM. A gradient smoothing operation is then performed on second-order derivatives of shape functions to achieve the stabilization terms. Due to the use of divergence theory, the smoothing operation relaxes the requirement of shape functions, so that the square-residuals can be evaluated using linear elements. The effectiveness of the present stabilized NS-FEM is demonstrated via numerical examples.

Regeneration of Silica‐Supported Silicotungstic Acid as a Catalyst for the Dehydration of Glycerol

The dehydration reaction of glycerol to acrolein is catalyzed by acid catalysts. These catalysts tend to suffer from the formation of carbonaceous species on their surface (coking), which leads to substantial degradation of their performances (deactivation). To regenerate the as-deactivated catalysts, various techniques have been proposed so far, such as the co-feeding of oxygen, continuous regeneration by using a moving catalytic bed, or alternating between reaction and regeneration. Herein, we study the regeneration of supported heteropolyacid catalysts. We show that the support has a strong impact on the thermal stability of the active phase. In particular, zirconia has been found to stabilize silicotungstic acid, thus enabling the nondestructive regeneration of the catalyst. Furthermore, the addition of steam to the regeneration feed has a positive impact by hindering the degradation reaction by equilibrium displacement. The catalysts are further used in a periodic reaction/regeneration process, whereby the possibility of maintaining long-term catalytic performances is evidenced.

Activity of LUF6000 and LUF6096 as positive allosteric modulators (PAMs) for the A3 adenosine receptor (AR) is species‐dependent

PAMs including the imidazoquinolinamine derivative LUF6000 and the quinoline derivative LUF6096 have recently been discovered for the human A3AR. These agents increase the maximal efficacy of orthosteric agonists and slightly increase or have not effect on potency. Given that orthosteric pharmacology of the A3AR differs markedly among species, the goal of this study was to characterize the activity of LUF6000 and LUF6096 for the A3AR from non‐human species commonly used in preclinical drug research. Functional modulation was assessed with a [35S]GTPγS binding assay using membranes prepared from HEK 293 cells stably expressing recombinant A3ARs. We found that both LUF6000 and LUF6096 produced substantial enhancing activity with the canine and rabbit, but not with mouse or rat A3ARs. In responsive species, both modulators increased the maximal efficacy of the partial A3AR agonist Cl‐IB‐MECA as well as the native ligand adenosine more than two‐fold. A decrease in potency was detected with the canine (but not the rabbit) A3AR explained by an effect of the modulators to decrease orthosteric binding affinity determined in equilibrium displacement binding assays with the orthosteric agonist radioligand [125I]I‐AB‐MECA. Our results reveal that allosteric pharmacology of the A3AR is species‐dependent. Supported by the NIH (R01HL077707 and NIDDK Intramural Research Program).

The Effects of Farm Commodity and Retail Food Policies on Obesity and Economic Welfare in the United States

Many commentators claim that farm subsidies have contributed significantly to the “obesity epidemic” by making fattening foods relatively cheap and abundant and, symmetrically, that taxing “unhealthy” commodities or subsidizing “healthy” commodities would contribute to reducing obesity rates. In this article we use an equilibrium displacement model to estimate and compare the economic welfare effects from a range of hypothetical farm commodity and retail food policies as alternative mechanisms for encouraging consumption of healthy food or discouraging consumption of unhealthy food, or both. We find that, compared with retail taxes on fat, sugar, or all food, or subsidies on fruits and vegetables at the farm or retail levels, a tax on calories would be the most efficient obesity policy. A tax on calories would have the lowest deadweight loss per pound of fat reduction in average adult weight, and would yield a net social gain once the impact on public health care expenditures is considered.

Pharmaceutical and biomedical applications of affinity chromatography: Recent trends and developments

Affinity chromatography is a separation technique that has become increasingly important in work with biological samples and pharmaceutical agents. This method is based on the use of a biologically related agent as a stationary phase to selectively retain analytes or to study biological interactions. This review discusses the basic principles behind affinity chromatography and examines recent developments that have occurred in the use of this method for biomedical and pharmaceutical analysis. Techniques based on traditional affinity supports are discussed, but an emphasis is placed on methods in which affinity columns are used as part of HPLC systems or in combination with other analytical methods. General formats for affinity chromatography that are considered include step elution schemes, weak affinity chromatography, affinity extraction and affinity depletion. Specific separation techniques that are examined include lectin affinity chromatography, boronate affinity chromatography, immunoaffinity chromatography, and immobilized metal ion affinity chromatography. Approaches for the study of biological interactions by affinity chromatography are also presented, such as the measurement of equilibrium constants, rate constants, or competition and displacement effects. In addition, related developments in the use of immobilized enzyme reactors, molecularly imprinted polymers, dye ligands and aptamers are briefly considered.

Magnetic Force Characteristics and Structure of a Novel Radial Hybrid Magnetic Bearing

There are some problems in the permanent magnetic circuit of the current permanent magnet biased magnetic bearings, such as small magnetic force, low magnetic flux density and lack of self-stabilization. To solve this problem, a new hybrid radial magnetic bearing structure has been proposed. The nonlinear model and linearization equation of the new hybrid radial magnetic bearing capacity has been established by current molecular method and virtual displacement theorem. It is found that the permanent magnetic bearing can achieve self-stabilization in the radial degrees of freedom and can reduce the total displacement of negative stiffness. The results show that the air gap flux density is greatly improved by the new hybrid magnetic bearing with Halbach array structure. Current stiffness and displacement rigidity is closely related to initial current and initial gap of the equilibrium position. Near the equilibrium position, current stiffness and displacement rigidity are linear relationship. With the increase of air gap, it remains a good linearity. While with the decrease of air gap, it presents nonlinear characteristics..

Federal excise tax increase and its effects on U.S. tobacco production

Using the equilibrium displacement model, we examine the impact on tobacco farms of the decrease in cigarette sales due to the increase in prices induced by the federal excise tax hike that went to effect on April 1, 2009. First we estimate the effect of the increase in the federal excise tax on cigarette price and sales. Then, we estimate the effect of the decrease in cigarette sales on tobacco farms. Results suggest that under a scenario of market power implied by a conjectural elasticity of 0.11 manufactures could charge $0.23 per pack more than the federal excise tax increase, which would be enough to offset the estimated 1.42 billion-pack sales decline and to maintain the industry’s revenue net of taxes. This decrease in cigarette sales induced by the increase in the federal excise tax would result in the tobacco leaf output and price declining by 2.85 and 0.41%, respectively. As a result, the tobacco leaf sector would sustain a loss of 3.25% in revenue, amounting to nearly $48.4 million.

Time-dependent thermoelastic creep analysis of rotating disk made of Al–SiC composite

Time-dependent creep stress redistribution analysis of rotating disk made of Al–SiC composite is investigated using Mendelson’s method of successive elastic solution. All mechanical and thermal properties except Poisson’s ratio are radial dependent based on volume fraction percent of SiC reinforcement. The material creep behavior is described by Sherby’s constitutive model using Pandey’s experimental results on Al–SiC composite. Loading is an inertia body force due to rotation and a distributed temperature field due to steady-state heat conduction from inner to outer surface of the disk. Using equations of equilibrium, stress strain, and strain displacement, a differential equation, containing creep strains, for displacement is obtained. History of stresses and deformations are calculated using method of successive elastic solution. It is concluded that the uniform distribution of SiC reinforcement does not considerably influence on stresses. However, the minimum and most uniform distribution of circumferential and effective thermoelastic stresses belongs to composite disk of aluminum with 0% SiC at inner surface and 40% SiC at outer surface. It has also been found that the stresses, displacement, and creep strains are changing with time at a decreasing rate so that after almost 50 years the solution approaches the steady-state condition.

Axial creep loading and unloaded recovery of the human intervertebral disc and the effect of degeneration

The intervertebral disc maintains a balance between externally applied loads and internal osmotic pressure. Fluid flow plays a key role in this process, causing fluctuations in disc hydration and height. The objectives of this study were to quantify and model the axial creep and recovery responses of nondegenerate and degenerate human lumbar discs. Two experiments were performed. First, a slow compressive ramp was applied to 2000 N, unloaded to allow recovery for up to 24 h, and re-applied. The linear-region stiffness and disc height were within 5% of the initial condition for recovery times greater than 8 h. In the second experiment, a 1000 N creep load was applied for four hours, unloaded recovery monitored for 24 h, and the creep load repeated. A viscoelastic model comprised of a “fast” and “slow” exponential response was used to describe the creep and recovery, where the fast response is associated with flow in the nucleus pulposus (NP) and endplate, while the slow response is associated with the annulus fibrosus (AF). The study demonstrated that recovery is 3–4X slower than loading. The fast response was correlated with degeneration, suggesting larger changes in the NP with degeneration compared to the AF. However, the fast response comprised only 10%–15% of the total equilibrium displacement, with the AF-dominated slow response comprising 40%–70%. Finally, the physiological loads and deformations and their associated long equilibrium times confirm that diurnal loading does not represent “equilibrium” in the disc, but that over time the disc is in steady-state.

A pig in a poke? Accounting for uncertainty about elasticity values in an EDM of the Australian pig industry

Recently Griffith et al. (2010) updated an existing equilibrium displacement model (EDM) of the Australian pig industry which was then used by Slattery et al. (2010) to estimate the potential industry impacts from an increase in demand for low cholesterol pork (see Bellhouse et al. 2010). In that model the specified market parameters were chosen on the basis of economic theory, previous studies and some assumptions made by the authors. While it was concluded those values adequately represented the price responsiveness of market participants within the industry, uncertainty still exists about their true values. This may have implications for the results generated from the model. In this paper stochastic sensitivity analysis is undertaken to account for that uncertainty. Overall, the EDM results are found to be relatively robust. However, the methodology used allows for the calculation of probabilities to determine the chances of a result contrary to that obtained using the original point estimates. These calculations suggest the rankings of alternative industry investments may change for particular combinations of parameter values, away from the rankings implied by the point estimates, and that an investment shown to have a positive return of $0.67 million using the point investments may in fact vary from a loss of $0.1 million to a gain of $1.14 million with 95 per cent probability under the stochastic sensitivity analysis.

Versatile microanalytical system with porous polypropylene capillary membrane for calibration gas generation and trace gaseous pollutants sampling applied to the analysis of formaldehyde, formic acid, acetic acid and ammonia in outdoor air

The analytical determination of atmospheric pollutants still presents challenges due to the low-level concentrations (frequently in the μg m −3 range) and their variations with sampling site and time. In this work, a capillary membrane diffusion scrubber (CMDS) was scaled down to match with capillary electrophoresis (CE), a quick separation technique that requires nothing more than some nanoliters of sample and, when combined with capacitively coupled contactless conductometric detection (C 4D), is particularly favorable for ionic species that do not absorb in the UV–vis region, like the target analytes formaldehyde, formic acid, acetic acid and ammonium. The CMDS was coaxially assembled inside a PTFE tube and fed with acceptor phase (deionized water for species with a high Henry's constant such as formaldehyde and carboxylic acids, or acidic solution for ammonia sampling with equilibrium displacement to the non-volatile ammonium ion) at a low flow rate (8.3 nL s −1), while the sample was aspirated through the annular gap of the concentric tubes at 2.5 mL s −1. A second unit, in all similar to the CMDS, was operated as a capillary membrane diffusion emitter (CMDE), generating a gas flow with know concentrations of ammonia for the evaluation of the CMDS. The fluids of the system were driven with inexpensive aquarium air pumps, and the collected samples were stored in vials cooled by a Peltier element. Complete protocols were developed for the analysis, in air, of NH 3, CH 3COOH, HCOOH and, with a derivatization setup, CH 2O, by associating the CMDS collection with the determination by CE-C 4D. The ammonia concentrations obtained by electrophoresis were checked against the reference spectrophotometric method based on Berthelot's reaction. Sensitivity enhancements of this reference method were achieved by using a modified Berthelot reaction, solenoid micro-pumps for liquid propulsion and a long optical path cell based on a liquid core waveguide (LCW). All techniques and methods of this work are in line with the green analytical chemistry trends.

Animal Identification and Tracing in the United States

We examine the impacts of adopting animal identification and tracing systems on the U.S. meat and livestock industry. Using a multimarket equilibrium displacement model, we find that a modest increase in domestic demand for beef would offset the costs of an animal identification system. Similarly, an increase in beef export demand equivalent to Japan's beef export market share prior to the 2003 U.S. discovery of bovine spongiform encephalopathy would offset animal identification system costs.

Impactos potenciais do Protocolo de Cartagena sobre biossegurança nas exportações brasileiras de soja

O objetivo deste trabalho é verificar os impactos do Protocolo de Cartagena sobre Biossegurança (PCB) para o Brasil no mercado internacional, dado que o País foi o único grande exportador de commodities agrícolas que o ratificou. A análise centrou-se nas discussões do Artigo 18 e no mercado de soja. Calcularam-se os custos adicionais de identificação para Brasil, Argentina e Estados Unidos, com base em propostas feitas durante as negociações. Os números mostraram que esses custos são mais elevados no Brasil e que a diferença em relação aos países concorrentes aumenta quando as exigências de identificação tornam-se mais rígidas. Para verificar o impacto desses custos no mercado internacional, utilizou-se o Equilibrium Displacement Model (EDM) e definiram-se dois cenários. Em um deles, apenas o Brasil cumpriria as normas do PCB e em outro, Argentina e EUA também adotariam medidas equivalentes. Os resultados evidenciaram que ambas as situações implicariam em perdas para o Brasil, que poderiam chegar a US$ 133 milhões no Cenário 1 e a US$ 329 milhões no Cenário 2. Para os outros países, o Cenário 2 apresenta dados mais favoráveis. Dessa forma, espera-se que Argentina e EUA adotem medidas semelhantes às exigidas pelo PCB, no qual o Brasil incorre em perdas maiores.

Phase transitions to cooperation in the prisoner’s dilemma

Game theory formalizes certain interactions between physical particles or between living beings in biology, sociology, and economics and quantifies the outcomes by payoffs. The prisoner's dilemma (PD) describes situations in which it is profitable if everybody cooperates rather than defects (free rides or cheats), but as cooperation is risky and defection is tempting, the expected outcome is defection. Nevertheless, some biological and social mechanisms can support cooperation by effectively transforming the payoffs. Here, we study the related phase transitions, which can be of first order (discontinuous) or of second order (continuous), implying a variety of different routes to cooperation. After classifying the transitions into cases of equilibrium displacement, equilibrium selection, and equilibrium creation, we show that a transition to cooperation may take place even if the stationary states and the eigenvalues of the replicator equation for the PD stay unchanged. Our example is based on adaptive group pressure, which makes the payoffs dependent on the endogenous dynamics in the population. The resulting bistability can invert the expected outcome in favor of cooperation.

An equilibrium displacement approach to oligopoly market analysis: an application to trade in the Korean infant formula market

AbstractThis article uses an equilibrium displacement model (EDM) to assess the impact of a change in trade policy in the Korean infant formula market that is assumed to be oligopolistic. Domestic oligopolists compete in a market for a homogenous good with importing firms who enjoy the same level of market power as the domestic producers. Within an EDM framework, we investigate how the market adjusts to a new equilibrium in response to an external policy shock that improves access to foreign goods. Our empirical work consists of two steps. We first econometrically estimate the market demand elasticity and market power parameter. Then, using these estimates, we simulate our EDM model to assess the distributional effects of tariff cuts and other changes in marginal cost. Simulation results show that, with a lower market price and increased consumption, the change in consumer surplus resulting from tariff reduction is unambiguously positive, but that the change in social welfare can be in either direction, depending on who receives market rents associated with imports. When importing firms are domestic, the domestic welfare change is definitely positive. However, in the case of foreign importing firms, the direction of the welfare change crucially depends on the demand elasticity.

Potential Payoff from R&D in the Coconut Industry of North Sulawesi, Indonesia

The coconut industry of North Sulawesi, one of the primary coconut‐producing provinces of Indonesia, is dominated by a small number of products that are primarily exported overseas. As they only comprise a small share of the global coconut product export market, demand for coconut products from North Sulawesi is generally very elastic. Conversely, the supply of coconuts is highly inelastic, especially in the short to medium term. Hence, small shifts in supply and demand lead to large fluctuations in farmer incomes. In this context, an equilibrium displacement model is used to examine the intra‐industry consequences of R&D investments in farm productivity and product development. These investments are assessed in terms of the producer surplus benefits that they generate.

Sulfide Binding Properties of Truncated Hemoglobins

The truncated hemoglobins from Bacillus subtilis (Bs-trHb) and Thermobifida fusca (Tf-trHb) have been shown to form high-affinity complexes with hydrogen sulfide in their ferric state. The recombinant proteins, as extracted from Escherichia coli cells after overexpression, are indeed partially saturated with sulfide, and even highly purified samples still contain a small but significant amount of iron-bound sulfide. Thus, a complete thermodynamic and kinetic study has been undertaken by means of equilibrium and kinetic displacement experiments to assess the relevant sulfide binding parameters. The body of experimental data indicates that both proteins possess a high affinity for hydrogen sulfide (K = 5.0 x 10(6) and 2.8 x 10(6) M(-1) for Bs-trHb and Tf-trHb, respectively, at pH 7.0), though lower with respect to that reported previously for the sulfide avid Lucina pectinata I hemoglobins (2.9 x 10(8) M(-1)). From the kinetic point of view, the overall high affinity resides in the slow rate of sulfide release, attributed to hydrogen bonding stabilization of the bound ligand by distal residue WG8. A set of point mutants in which these residues have been replaced with Phe indicates that the WG8 residue represents the major kinetic barrier to the escape of the bound sulfide species. Accordingly, classical molecular dynamics simulations of SH(-)-bound ferric Tf-trHb show that WG8 plays a key role in the stabilization of coordinated SH(-) whereas the YCD1 and YB10 contributions are negligible. Interestingly, the triple Tf-trHb mutant bearing only Phe residues in the relevant B10, G8, and CD1 positions is endowed with a higher overall affinity for sulfide characterized by a very fast second-order rate constant and 2 order of magnitude faster kinetics of sulfide release with respect to the wild-type protein. Resonance Raman spectroscopy data indicate that the sulfide adducts are typical of a ferric iron low-spin derivative. In analogy with other low-spin ferric sulfide adducts, the strong band at 375 cm(-1) is tentatively assigned to a Fe-S stretching band. The high affinity for hydrogen sulfide is thought to have a possible physiological significance as H(2)S is produced in bacteria at metabolic steps involved in cysteine biosynthesis and hence in thiol redox homeostasis.