Stock Accumulation Research Articles

Commodity storage with durable shocks: a simple Markovian model

We model an economy that alternates randomly between abundance and scarcity episodes. We characterize in detail the structure of the Markovian competitive equilibrium. Accumulation and drainage of stocks are the main focuses. Economically appealing comparative statics results are proved. We also characterize the stationary distribution of states. We extend the model to discuss price stabilization policies, injection and release costs, and limited storage capacity. Overall, the analysis delineates the notion of “flexible economy.”

Evaluation of Life Cycle Assessment Recycling Allocation Methods

SummaryLife cycle assessment practitioners struggle to accurately allocate environmental burdens of metals recycling, including the temporal dimension of environmental impacts. We analyze four approaches for calculating aluminum greenhouse gas emissions: the recycled content (RC) or cut‐off approach, which assumes that demand for recycled content displaces primary production; end‐of‐life recycling (EOLR), which assumes that postuse recycling displaces primary production; market‐based (MB) approaches, which estimate changes in supply and demand using price elasticities; and value‐corrected substitution (VCS), which allocates impact based on price differences between primary and recycled material. Our analysis suggests that applications of the VCS approach do not adequately account for the changing scrap to virgin material price ratio over time, whereas MB approaches do not address stock accumulation and depletion. The EOLR and RC approaches were analyzed using two case studies: U.S. aluminum beverage cans and vehicle engine blocks. These approaches produced similar results for beverage cans, which have a closed material loop system and a short product life. With longer product lifetimes, as noted with the engine blocks, the magnitude and timing of the emissions differs greatly between the RC and EOLR approaches. The EOLR approach indicates increased impacts at the time of production, offset by negative impacts in future years, whereas the RC approach assumes benefits to increased recycled content at the time of production. For vehicle engine blocks, emissions using EOLR are 140% higher than with RC. Results are highly sensitive to recycled content and future recycling rates, and the choice of allocation methods can have significant implications for life cycle studies.

Radiation Safety Issues of Using Regenerated Uranium in Nuclear Fuel Manufacturing at the Electrostal Plant

Concerns about potential shortage of natural uranium and its increased cost, as well as the accumulation of stocks of regenerated uranium, created interest in using regenerated uranium in the process of manufacturing fuel assemblies for power reactors. However, using regenerated uranium in the fuel manufacturing process presents significant challenges from the radiation safety point of view, as this uranium contains radioactive isotopes associated with uranium-232. To explore the possibility of using regenerated uranium in the fuel manufacturing process, the Electrostal Machine-Building Plant explored the possibility of using uranium with uranium-232 concentrations of up to 5 ppb. The results of the pilot project suggest that large-scale production of reactor fuel from uranium with high concentrations of uranium-232 would require a substantial change of the technological processes and procedures for storage and handling and storage of the fuel produced with this uranium.

Organic amendments affect δ13C signature of soil respiration and soil organic C accumulation in a long‐term field experiment in Sweden

SummaryThe contribution of young and old soil organic carbon (SOC) pools to soil CO2 fluxes and specific respiration rates of these fluxes was determined by using δ13C signatures in the Ultuna long‐term continuous soil organic matter experiment (C‐SOME). Initiated in 1956, the experiment had a range of treatments amended organically and with mineral nitrogen fertilizer under C3 cultivation until 1999, and thereafter under C4 (maize) cultivation. In 2011, soil respiration was measured in situ prior to planting, during growth and after harvest. The contributions from C4‐ and C3‐C as well as their specific respiration rates were estimated from δ13C differences in SOC and CO2 fluxes. The contributions from C4‐C sources were further separated into autotrophic and heterotrophic respiration by comparing respiration rates before and after harvest. Between 165 and 385 g C4‐C m−2 accumulated during 10 years of maize growth, contributing between 4.9 and 8.1% to the total SOC stock. Although recent C4‐C had an average specific respiration rate that was 8.4–22.6 times greater than C3‐C, total soil respiration was generally equally split between C3‐C and C4‐C. Both pools are therefore important sources of CO2 in the overall C budget, and a crucial factor in accounting for SOC stock change caused by management. Experimental treatments influenced specific respiration rates of C4 plant material and accumulation of SOC stock, demonstrating how greater SOC accumulation can be favoured by high‐quality C inputs.

Seasonal fluctuations of deep megabenthos: Finding evidence of standing stock accumulation in a flux-rich continental slope

Throughout the deep oceans, diversity in the benthos peaks at intermediate slope depths. In the western Mediterranean lower slope an accumulation of biomass, but not diversity, at depths of 1200–1350m has been observed. However, the precise causes of this biomass peak are unknown. We examined the patterns of megafauna benthic biomass in the Catalan sea open slope, from 900 to 1750m depth, expanding the results in the context of the whole continental margin. Sampling was carried out by combining an Otter-Trawl Maireta System (OTMS) and an Agassiz trawl, during four different seasons in 2008/2009. At the same time, current speed, temperature and salinity were obtained year-round by means of near-bottom deployed sensors (current meters and temperature-conductivity sensors). Total biomass followed an inverted U-shaped pattern, peaking at depths of 1050–1350m. Range-related ecological forcings between shallower and deeper species may have caused this biomass accumulation at intermediate slope depths. We also report on the seasonal variations of biomass in the studied depth range, identifying a dynamic zone above 1000m depth where populations of highly mobile species perform year-round migrations throughout the slope, and a more static region below 1000m (i.e. the twilight zone end) with substantially less inter-annual variations. The arrival of new Western Mediterranean Deep Water from the deep basin to the lower slope in March–May may have driven the accumulation of biomass at 900 and 1050m depth over the same period. In addition, an adjacent submarine canyon was sampled with the same procedures to characterize its benthic megafauna community. Analyses revealed higher diversity, but not biomass, inside the canyon than in the adjacent open slope, and a significantly different assemblage composition between the two habitats. These results strengthen the concept of submarine canyons as hotspots of biodiversity and underline the importance of their conservation as diversity repositories.

Steel all over the world: Estimating in-use stocks of iron for 200 countries

Industrialization and urbanization in the developing world have boosted steel demand during the recent two decades. Reliable estimates on how much steel is required for high economic development are necessary to better understand the future challenges for employment, resource management, capacity planning, and climate change mitigation within the steel sector. During their use phase, steel-containing products provide service to people, and the size of the in-use stock of steel can serve as an indicator of the total service level. We apply dynamic material flow analysis to estimate in-use stocks of steel in about 200 countries and identify patterns of how stocks evolve over time. Three different models of the steel cycle are applied and a full uncertainty analysis is conducted to obtain reliable stock estimates for the period 1700–2008.Per capita in-use stocks in countries with a long industrial history, e.g., the U.S, the UK, or Germany, are between 11 and 16tons, and stock accumulation is slowing down or has come to a halt. Stocks in countries that industrialized rather recently, such as South Korea or Portugal, are between 6 and 10tons per capita and grow fast. In several countries, per capita in-use stocks of steel have saturated or are close to saturation. We identify the range of saturation to be 13±2tons for the total per capita stock, which includes 10±2tons for construction, 1.3±0.5tons for machinery, 1.5±0.7tons for transportation, and 0.6±0.2tons for appliances and containers. The time series for the stocks and the saturation levels can be used to estimate future steel production and scrap supply.

A Quantitative Study of the Effect of Foreign Investment on Nonresident Patenting in Developing Countries, 1980-2010

This study examines whether foreign investment is a significant predictor of nonresident patent counts in developing countries over time. Unbalanced panel data are observed for 64 developing countries over a 31 year time period from 1980 to 2010 to test a hypothesis stating that countries with higher levels of inward accumulated foreign direct investment (FDI) stocks have higher nonresident patent counts, controlling for other explanatory factors such as population size, level of economic development, education rates, government expenditures, levels of domestic investment, and resident patent counts. Predicted counts of nonresident patents are estimated with Random Effects Negative Binomial (RENB) regression to model the effects of different independent variables on nonresident patenting in each country. Results confirm this study’s hypothesis by showing a significant and robust positive effect for accumulated FDI stocks on nonresident patent counts, while controlling for the effects of other variables over time in the sample of 64 developing countries included in this analysis. This study advances a sociological approach to theories of intellectual property and posits the accumulation of FDI stock as critical to predicting patterns of ownership of intangible capital wealth in developing countries over time. It remains to be seen if developed country FDI influences nonresident patent activities in similar or different ways to developing countries. Future studies may compare between groups of developed and developing countries to determine if nonresident and resident patent activities evolve in the same fashion. Finally, future research may also focus on the nuances between different types of intellectual property (patents, copyrights, trademarks, etc.) in order to more accurately predict each class of intangible capital wealth.

Total carbon accumulation in a tropical forest landscape

BackgroundRegrowing tropical forests worldwide sequester important amounts of carbon and restore part of the C emissions emitted by deforestation. However, there are large uncertainties concerning the rates of carbon accumulation after the abandonment of agricultural and pasture land. We report here accumulation of total carbon stocks (TCS) in a chronosequence of secondary forests at a mid-elevation landscape (900-1200 m asl) in the Andean mountains of Colombia.ResultsWe found positive accumulation rates for all ecosystem pools except soil carbon, which showed no significant trend of recovery after 36 years of secondary succession. We used these data to develop a simple model to predict accumulation of TCS over time. This model performed remarkably well predicting TCS at other chronosequences in the Americas (Root Mean Square Error < 40 Mg C ha-1), which provided an opportunity to explore different assumptions in the calculation of large-scale carbon budgets. Simulations of TCS with our empirical model were used to test three assumptions often made in carbon budgets: 1) the use of carbon accumulation in tree aboveground biomass as a surrogate for accumulation of TCS, 2) the implicit consideration of carbon legacies from previous land-use, and 3) the omission of landscape age in calculating accumulation rates of TCS.ConclusionsOur simulations showed that in many situations carbon can be released from regrowing secondary forests depending on the amount of carbon legacies and the average age of the landscape. In most cases, the rates used to predict carbon accumulation in the Americas were above the rates predicted in our simulations. These biome level rates seemed to be realistic only in landscapes not affected by carbon legacies from previous land-use and mean ages of around 10 years.

Analysis of material stock accumulation in China’s infrastructure and its regional disparity

Materials stocked in infrastructure provide necessary personal and economic services, and are also closely linked with massive resource extraction, energy consumption and waste generation. To support policy deliberations toward regional harmony and sustainable development, this paper examines the temporal change during 1978–2008 and spatial patterns of ten types of materials stocked in four major infrastructures (residential buildings, roads, railways, and water pipelines) in 31 provinces in China, and diagnoses regional disparity and driving factors by Theil index and multivariable regression based on panel data. It was found that the total material stock has boomed to 42.5 billion tons in 2008, with its per capita level increased by nine times over that in 1978. Over 90 % of materials are concentrated in residential buildings and roads, and are spatially inclined to decrease from coastal regions to inland areas. Since China has shifted its strategy from an inclined to harmonious regional development, the overall inequality of per capita material stock has been changing toward equality with its scale contributed mainly by inter-regional inequality, and downward trend affected dominantly by intra-regional inequality. To balance the growth speed across regions meanwhile, to develop economy and attract foreign investment in each region, would be a promising route towards reducing regional inequality. Moreover, the enhancement of governmental performance and construction of each sector’s share would also be effective for decreasing inter-regional gaps.

Carbon and Nitrogen Content and Stock in No-Tillage and Crop-livestock Integration Systems in the Cerrado of Goias State, Brazil

The objective of this study was to evaluate the total organic carbon (TOC) and nitrogen content, and quantify the TOC and nitrogen stocks in land use systems in the Cerrado region of Goiás State, Brazil. A crop-livestock integration system (CLIS) was evaluated - (corn+brachiaria/beans/cotton/soya beans) and a no-tillage system (NTS) - (sunflower/millet/soya beans/corn). The vegetal coverage of the natural Cerrado, adjacent to the NTS and CLIS, was considered as the original soil condition. Soil samples were collected at layer depths of 0.0-10.0 cm, 10.0-20.0 cm, 20.0-30.0 cm, 30.0-40.0 cm, 40.0-50.0 cm, 50.0-60.0 cm, 60.0-80.0 cm, and 80.0-100.0 cm, in a full random experimental design. The CLIS had higher contents of TOC and N than the NTS up to a level of 30.0 cm. Higher nitrogen stocks were observed in the Cerrado. In the CLIS, higher TOC contents were found up to 30.0 cm and nitrogen contents up to 20.0 cm. The sum of stocks up to a depth of 100 cm for TOC and 40 cm for nitrogen was greater in the CLIS when compared to the NTS. Under the CLIS, the stocks of TOC (0.0-30.0 cm) and nitrogen (0.0-20.0 cm) increased in relation to those of the NTS. The CLIS was more efficient in stock accumulation than the Cerrado for the sum of layers 0.0-40.0 cm and 0.0-60.0 cm.

The North American Third-Party Logistics Industry in 2011: The Provider CEO Perspective

The North American Third-Party Logistics Industry in 2011: The Provider CEO Perspective

The New Investment Paradigm?

This article in the Economic Insights series summarizes results from current Statistics Canada research on investment and capital stock accumulation. It reports on the study, Intangible Capital and Productivity Growth in Canada. Compiling information on wealth accumulation has been central to Statistics Canada’s activities since its inception. The wealth of the nation is a measure of its financial strength, international standing, and economic power. In 1915, Canada’s first Chief Statistician, Robert H. Coats, compiled Canada’s initial estimate of national wealth at the behest of the Borden Conservatives. He set the value of Canada at $16.3 billion. Since then, the practice of compiling national wealth estimates has continued, with current national balance sheet estimates placing Canada’s 2011 wealth at $6.9 trillion. Over time, the accuracy with which national wealth is estimated has improved, and the scope of assets examined has expanded. This process involved debate about which assets should be included, and how they should be measured.

Equilibrium Storage in a Markov Economy

We model an economy that alternates randomly between abundance and scarcity episodes. We develop an original method to characterize in detail the structure of the Markovian competitive equilibrium. Accumulation and drainage of stocks are the main focuses. Economically appealing comparative statics results are proved. We also characterize stationary distribution of states. We extend the model to discuss price stabilization policies, injection and release costs, and limited storage capacity. Overall, the analysis delineates the notion of flexible economy.

Banking reform and SME financing in Ethiopia: Evidence from the manufacturing sector

This study investigates the effect of banking reform on Small and Medium Enterprise (henceforth SMEs) access to bank credit during post-liberalization period 1994 to 2007. Aiming at casting light on the changes in the country’s banking sector, bank concentration, competition, efficiency, and liquidity have been assessed. In addition, survey of 102 randomly selected manufacturing SME has been conducted to examine changes in SME access to bank loan. Assessment of changes in the banking sector reveals that the sector has become less concentrated. However, competition among banks is weak, which is manifested through operational inefficiency and accumulation of large stock of liquidity. This led to persistence of lack of access to bank loan even after the reform. The study also finds that access to loan is limited across firms of different age groups, ownership forms, and at different stages of SME development. In general, despite the introduction of banking sector reform in 1994 that led to expansion of the banking industry, SMEs’ problem of credit access has persisted. This implies that changes in the banking sector structure per se are not sufficient to introduce competition in the banking industry and an improvement in SME credit access. Policy makers should therefore devise mechanisms that enhance competition in the banking sector and establish a policy framework that encourages them to lend to the SME sector. Key words: Ethiopian financial sector, Banking reform, SME financing, manufacturing sector, credit Access.

No rapid soil carbon loss after a windthrow event in the High Tatra

Windthrows are among the most important disturbances of forest ecosystems in Europe, with expected increasing frequency due to climate change. However, surprisingly little is known about soil carbon dynamics after windthrow mainly due to missing field assessments. After a large windthrow event in the High Tatra Mountains in 2004 three soil monitoring plots were established, one at a non-harvested windthrow left for natural succession, one at a harvested windthrow and one at a reference forest site which remained unaffected by the storm event. No loss in soil organic carbon (SOC) stocks was detected at the two windthrow sites with three inventories over the 3.5years after the storm event. However, shifts within the organic layers and the mineral soil toward more decomposed organic matter were found. Increasing C/N ratios at the harvested windthrow site indicate that newly established herbaceous vegetation compensated the decline in tree litter input. At the non-harvested windthrow site a flush of needle litter from broken trees helped to sustain SOC stocks. In contrast, SOC stocks at the reference forest increased by 2.2Mgha−1year−1 with major SOC stock accumulation in the forest floor. An assessment of the sample size required to detect future SOC changes revealed that at the windthrow sites a similar sample size is required as in the undisturbed reference forest. Small scale heterogeneity was at such a level that paired sampling did not significantly reduce the number of required samples. However, the separation of forest floor layers and mineral soil was a major obstacle for efficient forest soil carbon monitoring. The required number of soil samples could be decreased by 45% with a simultaneous sampling of forest floor and upper mineral soil, leading to more reliable SOC inventories.

Emergency oil stocks in Southeastern and Eastern Europe: What explains variation in convergence towards the EU model?

The accumulation and maintenance of emergency oil stocks in accordance with the requirements of the European Union involve changes in legislation, the strengthening of national stockholding institutions and the attraction of investment. Despite these challenges, almost all Southeastern and Eastern European countries have begun to align their oil stockholding arrangements with the European model, albeit there is variation in the actual degree of convergence. The greatest convergence is observed for Croatia and the Former Yugoslav Republic of Macedonia. In marked contrast, the oil stockholding system of Moldova continues to be different from the European model. This study provides an overview of the Southeastern and Eastern European countries’ progress in approximating the European requirements for emergency oil stocks and identifies the factors responsible for the cross-country variation. The differences observed stem from the extent to which the countries are legally obliged to comply with the European provisions, their membership aspirations, levels of energy-related investment from the European Union, and dependence on oil imports.

Soil Quality and Crop Yields, After Utilization of Sewage Sludge on Agricultural Land, in the Moldavian Plain, Romania

Soil Quality and Crop Yields, After Utilization of Sewage Sludge on Agricultural Land, in the Moldavian Plain, Romania Investigations conducted at the Podu-Iloaiei Agricultural Research Station, Iaşi County, have studied the influence of different sewage sludge rates on yield quality and quantity and soil agrochemical characteristics. Trials were set up in a five year-crop rotation, winter rape-wheat-maize-sunflower-wheat. Sewage sludge was applied every 2 years at rates of 20, 30, 40 and 60 t/ha, with different mineral fertilizer rates, differentiated according to the growing plant. The Cambic Chernozem used for experiments had a clayey-loam texture (410 g clay, 310 g loam and 280 g sand), a weakly acid reaction and a mean supply with mobile phosphorus and a very good one with mobile potassium. Applying rates of 30 t/ha sewage sludge has resulted in the accumulation of mobile phosphate stock in soil of 57 mg/kg and the microelement content, mobile forms from soil, was of 7.9 mg/kg at Cu, 1.4 mg/kg at B, 6.8 mg/kg at Zn and 186 mg/kg at manganese. The combined use of mean rates of mineral fertilizers (N100P80), together with 40 t/ha sewage sludge has resulted in improving soil chemical characteristics and getting yield increases in winter rape of 1854 kg/ha (108 %). After 8 years since the application of a rate of 30 t/ha sewage sludge, soil pH has increased 0.4 units, while phosphorus and potassium content from soil has increased by 30 and 52 mg/ kg soil, respectively. Sewage sludge from the Iaşi Water Treatment Station, which was applied every two years at rates of 20 and 30 t/ha, has determined the increase in the organic carbon content from soil by 2.9 g/kg (18%) and 4.4 g/kg (28%), respectively, compared to the unfertilized variant. The copper and zinc content from grains in wheat and maize crops, fertilized with 30 t/ha sewage sludge, was by two-four times higher, compared to the unfertilized control.

Solving Flexible Job‐Shop Scheduling Problem Using Gravitational Search Algorithm and Colored Petri Net

Scheduled production system leads to avoiding stock accumulations, losses reduction, decreasing or even eliminating idol machines, and effort to better benefitting from machines for on time responding customer orders and supplying requested materials in suitable time. In flexible job‐shop scheduling production systems, we could reduce time and costs by transferring and delivering operations on existing machines, that is, among NP‐hard problems. The scheduling objective minimizes the maximal completion time of all the operations, which is denoted by Makespan. Different methods and algorithms have been presented for solving this problem. Having a reasonable scheduled production system has significant influence on improving effectiveness and attaining to organization goals. In this paper, new algorithm were proposed for flexible job‐shop scheduling problem systems (FJSSP‐GSPN) that is based on gravitational search algorithm (GSA). In the proposed method, the flexible job‐shop scheduling problem systems was modeled by color Petri net and CPN tool and then a scheduled job was programmed by GSA algorithm. The experimental results showed that the proposed method has reasonable performance in comparison with other algorithms.

The Role of Technology Diffusion on Industrial Export: Empirical Analysis of Iranian Economy

Abstract Recent theories of international economics deal with oriented innovation in reaction to economic incentives as a main engine of technological progress and competitiveness. The aim of this study is to investigate the role of real variables such as stock accumulation of domestic RD while the coefficient of inflation rate indicated that the rate of inflation has negative and significant effect on industrial export in the Iranian economy.

Tracking the Metal of the Goblins: Cobalt’s Cycle of Use

Cobalt is a vital element in many technological applications, which, together with its increasing end-use in batteries, makes it important to quantify its cycle of use. We have done so for the planet as a whole and for the three principal cobalt-using countries - China, Japan, and the United States - for 2005. Together, China, Japan, and the United States accounted for approximately 65% of the cobalt fabricated and manufactured into end-use products (a total of 37 Gg Co). A time residence model allowed calculations of in-use stock accumulation and recycled and landfilled flows. China had the largest accumulation of in-use stock at some 4.3 Gg Co, over half of which was comprised of consumer battery stock. More than half of the stock accumulation in the United States was estimated to be in aircraft, rocket, and gas turbine engines, with a total in-use stock accumulation of approximately 3 Gg Co. The largest amounts of cobalt landfilled in China, the United States, and the planet were from the "chemical and other uses" category, and Japan's largest landfilled flow was in consumer batteries.