Simple Dynamic Equilibrium Research Articles

A simple dynamic equilibrium model shows that high phosphatase activity in tropical forest soils could be explained by rapid microbial turnover

Microorganisms and plant roots secrete phosphatase to obtain phosphorus (P) by degrading organic P. Previous studies have reported high phosphatase activity in tropical forest soils, which has been attributed to poor soil P conditions. However, rapid microbial turnover in tropical forest soils can also contribute to the high soil phosphatase activity. To test this, a simplified dynamic equilibrium model was developed. This model was intentionally designed to exclude the pathways of P originating from rock weathering or P adsorption by soils, with the aim of assessing the specific effect of accelerated microbial turnover on soil phosphatase activity. This model showed that accelerated microbial turnover consistently leads to elevated phosphatase activity, irrespective of the parameters, under the assumed environmental condition with the same litter P input. This suggests that rapid soil microbial turnover may serve as another crucial factor contributing to the high phosphatase activity in tropical forest soils, where both moisture and temperature are high.

Stochastic-Metaheuristic Model for Multi-Criteria Allocation of Wind Energy Resources in Distribution Network Using Improved Equilibrium Optimization Algorithm

In this paper, a stochastic-meta-heuristic model (SMM) for multi-criteria allocation of wind turbines (WT) in a distribution network is performed for minimizing the power losses, enhancing voltage profile and stability, and enhancing network reliability defined as energy not-supplied cost (ENSC) incorporating uncertainty of resource production and network demand. The proposed methodology has been implemented using the SMM, considering the uncertainty modeling of WT generation with Weibull probability distribution function (PDF) and load demand based on the normal PDF and using a new meta-heuristic method named the improved equilibrium optimization algorithm (IEOA). The traditional equilibrium optimization algorithm (EOA) is modeled by the simple dynamic equilibrium of the mass with proper composition in a control volume in which the nonlinear inertia weight reduction strategy is applied to improve the global search capability of the algorithm and prevent premature convergence. First, the problem is implemented without considering the uncertainty as a deterministic meta-heuristic model (DMM), and then the SMM is implemented considering the uncertainties. The results of DMM reveal the better capability of the IEOA method in achieving the lowest losses and the better voltage profile and stability and the higher level of the reliability in comparison with conventional EOA, particle swarm optimization (PSO), manta ray foraging optimization (MRFO) and spotted hyena optimization (SHO). The results show that in the DMM solving using the IEOA, traditional EOA, PSO, MRFO, and SHO, the ENSC is reduced from $3223.5 for the base network to $632.05, $636.90, $638.14, $635.67, and $636.18, respectively, and the losses decreased from 202.68 kW to 79.54 kW, 80.32 kW, 80.60 kW, 80.05 kW and 80.22 kW, respectively, while the network minimum voltage increased from 0.91308 p.u to 0.9588 p.u, 0.9585 p.u, 0.9584 p.u, 0.9586 p.u, and 0.9586 p.u, respectively, and the VSI improved from 26.28 p.u to 30.05 p.u, 30.03 p.u, 30.03 p.u, 30.04 p.u and 30.04 p.u; respectively. The results of the SMM showed that incorporating uncertainties increases the losses, weakens the voltage profile and stability and also reduces the network reliability. Compared to the DMM, the SMM-based problem is robust to prediction errors caused by uncertainties. Therefore, SMM based on existing uncertainties can lead to correct decision-making in the conditions of inherent-probabilistic changes in resource generation and load demand by the network operator.

Modeling of Interannual Snow and Ice Storage in High-Altitude Regions by Dynamic Equilibrium Concept

AbstractThe energy and mass balance model for terrestrial ice and snow is an essential tool for the future projection of interannual snow and ice storage including glaciers. However, the snow models in the hydrologic engineering field have barely considered the long-term behavior of the snow and ice storage because the time scale of glacier dynamics is much longer than those of river flow and seasonal snowmelt. This paper proposes an appropriate treatment for inland glaciers as systems in dynamic equilibrium that stay constant under a static climate condition. It is conjectured that the snow and ice vertical movement from high-elevation areas to valleys (lower elevation areas) by means of wind redistribution, avalanches, and glacial motion may be considered as an equilibrator of the snow and ice storage system because it stimulates snow and ice ablation. In order to demonstrate this concept, a simple dynamic equilibrium model for regional to global scales is proposed and applied to the Pamirs. The interan...

Monetary policy shocks and real commodity prices

In this paper we document the effects of monetary policy shocks on real commodity prices. Based on a VAR estimated using long-run restrictions, an expansionary monetary policy shock causes real commodity prices and output both to rise sharply for a short period of time. We find that a simple dynamic equilibrium model of commodity supply and demand can give a realistic response of real commodity prices to monetary policy shocks, for a wide range of parameter values. Furthermore, we find that based on historical simulations, shocks to monetary policy played an important role in commodity price fluctuations during the Great Recession, but they have contributed negligibly to commodity price movements overall since 1970. Even though monetary policy shocks have a robust and large marginal effect on real commodity prices, most monetary policy shocks are small, and most fluctuations in real commodity prices are correspondingly small.

On the evaluation of the horizontal forces produced by grain-like material inside silos during earthquakes

This paper presents analytical developments devoted to the evaluation of the effective behaviour of grain in flat-bottom silos during an earthquake. This research work starts from all the same basic assumptions of Eurocode 8 except for the one regarding the horizontal shear forces among consecutive grains. Only this difference leads to a new physically-based evaluation of the effective mass of the grain which horizontally pushes on the silo walls. The analyses are developed by simulating the earthquake ground motion with time constant vertical and horizontal accelerations and are carried out by means of simple dynamic equilibrium equations that take into consideration the specific mutual actions developing in the ensiled grain. The findings indicate that, in case of squat silos (characterized by low, but usual, height/diameter slenderness ratios), the portion of the grain mass that interacts with the silo walls turns out to be noticeably smaller than the total mass of the grain in the silo and the effective mass adopted by Eurocode 8.

Climate policies and learning by doing: Impacts and timing of technology subsidies

We study the role of technology subsidies in climate policies, using a simple dynamic equilibrium model with learning by doing. The optimal subsidy rate of a carbon-free technology is high when the technology is first adopted, but falls significantly over the next decades. However, the efficiency costs of uniform instead of optimal subsidies, may be low if there are adjustment costs for a new technology. Finally, supporting existing energy technologies only, may lead to technology lock-in, and the impacts of lock-in increase with the learning potential of new technologies as well as the possibilities for early entry.

Climate Policies and Induced Technological Change: Impacts and Timing of Technology Subsidies

We study the role of technology subsidies in climate policies, using a simple dynamic equilibrium model with learning-by-doing. The optimal subsidy rate of a carbon-free technology is high when the technology is first adopted, but falls significantly over the next decades. However, the efficiency costs of uniform instead of optimal subsidies, may be low if there are introduction or expansion constraints for a new technology. Finally, supporting existing energy technologies only, may lead to technology lock-in, and the impacts of lock-in increase with the learning potential of new technologies as well as the possibilities for early entry and thight carbon constraints.

Matrix proteins can generate the higher order architecture of the Golgi apparatus.

The Golgi apparatus in animal cells comprises a reticulum of linked stacks in the pericentriolar and often in the juxtanuclear regions of the cell. The unique architecture of this organelle is thought to depend on the cytoskeleton and cytoplasmic matrix proteins--the best characterized being the golgin family of fibrous, coiled-coil proteins and the GRASP family of stacking proteins. Here we show that these matrix proteins can be separated from oligosaccharide-modifying enzymes in the Golgi stack without affecting their ability to form a ribbon-like reticulum in the correct location near to the nucleus. Our data suggest that the Golgi is a structural scaffold that can exist independently of, but is normally populated by, the enzyme-containing membranes that modify transiting cargo. This new concept of the Golgi further indicates that the Golgi may be an autonomous organelle rather than one that is in simple dynamic equilibrium with the endoplasmic reticulum.

Microstructural Study of Centrifugally Atomized Powders of Al–Li and Al–Li–Fe Alloys

Powders of the Al–Li and Al–Li–Fe alloys were produced by a centrifugal atomizing method, and the main structural characteristics of the powder particles were studied. We present a detailed description of the atomizing method, which was found to produce an appropriated distribution in size of the powder particles, for further consolidation and manufacturing processes. Also, a semi-empirical calculation based on simple dynamic equilibrium considerations is presented, which was found to predict fairly well the measured values of the mean diameter of the powder particles.

A simple dynamic equilibrium model with adjustment costs

The equivalence of a perfect foresight equilibrium to a Fisher competitive equilibrium and an optimal planning model is demonstrated for a model with an adjustment cost technology and a representative household. Adjustment costs lead to a non-trivial dynamic optimization problem for the producer. The results depend on the necessity of a transversality condition for the household, producer and planner in their respective optimization problems. The equivalence theorems are used to discuss conditions for multiple steady state equilibrium solutions and the corresponding stability properties.