154 research outputs found
Global trends in raw materials consumption
No full textThis paper reviews movements in raw materials consumption over the past 30 years. Included in this review are all base metals and steel, and important agricultural raw materials. These primary commodities share the common characteristic that they are used as inputs in manufacturing and construction. Some metals and minerals, energy commodities, and timber products are not included in this review for various reasons. The period reviewed is from 1961 to 1988. A prominent characteristic of the metals market during the past 15 years has been its very slow growth. In some years consumption of several raw materials has even declined. Explaining the causes of this slowdown, in the face of moderate economic growth, has become a topical issue. The slowdown has important implications for a number of developing countries that rely heavily on exports of these materials. The severity and persistence of post-1973 declines in metals intensity per unit of GNP, prompted the conjecture that it may have been structural. This paper reviews the debate on this issue, including results of statistical tests. It also summarizes the trends in raw materials consumption and reviews the technological developments relating to raw materials consumption.Mining&Extractive Industry (Non-Energy),Montreal Protocol,Sanitation and Sewerage,Primary Metals,Environmental Economics&Policies
Thermal History Effects on Moisture Absorption of Fiber-Reinforced Polymer Composites
No full textFiber-reinforced polymer composites may offer numerous attractive features such as low cost, high specific performance, and ease of production. However, there are concerns about the overall durability of these materials, especially for sustained performance under severe and changing environmental conditions. There also is a general lack of data on the effects of life-cycle thermal history and temporal changes on moisture absorption dynamics in polymer composites. This work investigates the effects of previous life-cycle thermal history on moisture absorption in resin transfer molded glass/epoxy composites. Disk-shaped parts were fabricated using EPON 815C resin and EPICURE 3282 curing agent. Reinforcement was provided by six layers of randomly-oriented planar glass fiber preforms, yielding approximately 32% fiber volume fraction. Samples cut from the molded disks were initially immersed in water at room temperature for 48 hours. The samples were then divided into three groups and subjected to 0ºC, -25ºC, or liquid nitrogen for another 48 hours to impose various levels of life-cycle damage. A set of specimens was subjected to the same absorption cycle at room temperature in order to characterize the baseline behavior of the composite samples. Afterwards, all samples went through a desorption cycle to remove the absorbed moisture. The specimens were then immersed in water at room temperature for 18 months. Their masses were measured at periodic intervals to quantify the amount of water absorbed. Moisture intake during the 18-month period was found to increase considerably in composite samples subjected to harsher environmental/thermal conditions. In addition, short beam shear strength and stiffness reductions after freezing and after moisture absorption were measured. SBSS and stiffness dropped considerably for all composite parts after thermal conditioning. Property drop was observed to be much more significant for the samples that were exposed to lower freezing temperatures before moisture absorption. As much as 28 and 17% reduction in SBSS and stiffness, respectively, was observed for samples subjected to liquid nitrogen. After saturation with moisture, additional property drops were observed in all composite samples.YesPeer reviewed and accepted for presentation at the 32nd International Conference of the Polymer processing Society
The legal framework for private sector development in a transitional economy : the case of Poland
No full textThe economies of Central and Eastern Europe are in the midst of a historic transition from central planning and state ownership to development of a market-driven private sector. This transition requires comprehensive changes in"rules of the game"- including the legal framework for economic activity. A market economy presupposes a set of property rights and a system of laws or customs that allow the exchange of those rights. The legal framework in a market economy has at least three basic functions: defining the universe of property rights; setting the rules for entry into and exit from productive activities; and setting the rules of market exchange. These legal tasks are accomplished by areas of law such as: company, foreign investment, bankruptcy, contract and competition law. Poland has a rich legal tradition dating from pre-socialist times, which was suppressed but not eliminated during its forty years of socialism. This tradition is being revised as the country moves toward a private market economy. The current legal framework in Poland closely follows other continental jurisdictions and has a clear and reasonable internal logic. Many of the laws are old, but most are flexible enough to permit a wide range of modern, market-oriented activity. Property law, however, remains a"jungle". The wide discretion and general lack of precedent create tremendous legal uncertainty that is sure to hamper private sector development.Environmental Economics&Policies,Banks&Banking Reform,Municipal Housing and Land,Legal Products,Land and Real Estate Development
Wages and unemployment in Poland : recent developments and policy issues
No full textThe authors review recent developments in wages, employment, and unemployment in Poland and discuss some of the main risks Poland faces in sustaining its stabilization effort. They find that: unemployment has increased dramatically with stabilization, but this increase cannot be said to reflect widespread economic adjustment and restructuring throughout the Polish economy; and wages showed a significant degree of downward flexibility - in real terms - at the beginning of the year, when firms faced a severe supply shock coupled with very tight credit. The wage policy still in force in Poland at the end of 1991 maintains a few undesirable features. The monthly indexation and the possibility of carrying forward the unused margins are among the policy's main drawbacks; another is the link between wages and profitability. The current wage policy could be replaced by a generalized agreement on the wage path, with synchronized six-month contracts. The wage path should be related to expected inflation and economywide productivity. This scheme would also have the advantage of being based on a consensual agreement instead of being perceived as being imposed as a punitive tax.Youth and Governance,Banks&Banking Reform,Economic Theory&Research,Health Monitoring&Evaluation,Environmental Economics&Policies
Nonlinear site amplification functions for Central and Eastern North America
No full textSite amplification functions are used to modify ground motions from a reference bedrock condition to a surface condition based on the geologic features of the site of interest. Site amplification has been extensively studied and evaluated empirically for seismic regions such as the Western United States where there are abundant ground motion recordings for many sites and earthquake events. In regions of relatively lower or infrequent seismicity, such as Central and Eastern North America (CENA), the lack of ground motion recordings and seismic site properties severely limits the empirical characterization of site amplification. This research uses site response simulations to develop site amplification functions for CENA.
The first part of this study is the development of 1,747,278 1-D linear elastic, equivalent linear, and nonlinear site response analyses. Simulations are designed to capture the variability in site conditions in CENA and the uncertainty in soil properties at individual sites. Site profiles are developed for 1,747,278 site response analyses, 582,426 each of linear elastic, equivalent linear and nonlinear 1-D analyses for 70,650 unique site profiles. The database of simulations is the largest of its kind. This study describes the process for generating VS profiles, soil and weathered rock material properties, and ground motions to represent the variability and uncertainty of site conditions in CENA.
The second part of this study is the modeling of the site response simulation data with linear and nonlinear site amplification functions for the response spectrum (RS) and Fourier amplitude spectrum (FAS) and a correction factor to convert site amplification from a 3000 m/s CENA hard rock condition to a 760 m/s condition. The modular RS amplification model includes terms for time averaged shear wave velocity in the top 30 m of a site (VS30), site natural period, soil depth, and site nonlinearity which can be coupled with empirically-developed linear empirical amplification models. Including site natural period into the amplification function is shown to greatly improve estimates of site response over models dependent only on VS30. The FAS site amplification model is the first model developed from simulations, and the first to include nonlinear amplification.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-05-01The student, Joseph Harmon, accepted the attached license on 2017-04-17 at 18:06.The student, Joseph Harmon, submitted this Dissertation for approval on 2017-04-17 at 18:18.This Dissertation was approved for publication on 2017-04-18 at 11:54.DSpace SAF Submission Ingestion Package generated from Vireo submission #10827 on 2017-08-10 at 15:05:54Made available in DSpace on 2017-08-10T20:33:01Z (GMT). No. of bitstreams: 3
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Synthesis and biological evaluation of novel pyrazole compounds.
No full textA novel dipyrazole ethandiamide compound and acid chloride of pyrazolo[3,4-d]pyrimidine 4(5H)-one were prepared and reacted with a number of nucleophiles. The resultant novel compounds were tested in several in vitro and in vivo assays. Three compounds inhibited the secretion of neurotoxins by human THP-1 monocytic cells at concentrations that were not toxic to these cells. They also partially inhibited both cyclooxygenase-1 and -2 isoforms. In animal studies, two compounds were notable for their anti-inflammatory activity that was comparable to that of the clinically available cyclooxygenase-2 inhibitor celecoxib. Modeling studies by using the molecular operating environment module showed comparable docking scores for the two enantiomers docked in the active site of cyclooxygenase-2.Copyright (C) 2012 American Chemical Society (ACS). All Rights Reserved.; Section Code: 1-3; CA Section Cross-references: 28; CODEN: BMECEP; CAS Registry Numbers: 1245747-32-3P; 1245747-33-4P; 1245747-34-5P; 1245747-35-6P; 1245747-36-7P; 1245747-37-8P Role: PAC (Pharmacological activity), SPN (Synthetic preparation), THU (Therapeutic use), BIOL (Biological study), PREP (Preparation), USES (Uses) (synthesis and biol. evaluation of novel pyrazole compds.); 64-04-0 (Phenethylamine); 79-37-8 (Oxalyl chloride); 100-63-0; 108-91-8 (Cyclohexanamine); 123-00-2 (4-Morpholinepropanamine); 123-06-8; 618-36-0; 2627-86-3; 3886-69-9 Role: RCT (Reactant), RACT (Reactant or reagent) (synthesis and biol. evaluation of novel pyrazole compds.); 5334-43-0P; 1245747-30-1P; 1245747-31-2P Role: RCT (Reactant), SPN (Synthetic preparation), PREP (Preparation), RACT (Reactant or reagent) (synthesis and biol. evaluation of novel pyrazole compds.)Source type: Electronic(1
Post trade liberalization policy and institutional challenges in Latin America and the Caribbean
No full textArgentina, Chile, Colombia, Jamaica, Trinidad and Tobago, and Uruguay undertook extensive trade reform at a time of crisis, at which time institutional reform was difficult to undertake. Many of the countries had become members of the General Agreement on Tariffs and Trade (GATT) in the late 1980s and anticipated institutional reform. Only later did they reform trade policymaking institutions to bring them somewhat in line with trade policy regimes and GATT rules. These countries have all used reference prices and antidumping provisions of GATT, rather than safeguards, to provide relief from import surges. They have all tried to centralize trade policy by moving it from different agencies into a single agency. Despite liberalization, some sectors -- including automobiles, textiles and agriculture -- remain protected. Lessons the author draws from experience in these coutries: 1) the deteriorating macroeconomic situations are the main challenge to maintaining open trade policy; 2) trade policymaking must be constantly reviewed to prevent reversals, and the costs of protection must be communicated to the public at large; 3) There must be short-run measures to help domestic activities adjust to short-run price movements and alleviate pressure for protection. The danger -- such measures (unrelated to long-run price trends) can become permanent. 4) external commitments (through WTO or customs unions) can be used to discourage a return to protection; 5) extending reform (to labor and capital markets and the regulatory framework) will help maintain and extend trade liberalization. Allowing factors of production to move smoothly from one activity to another could help prevent the buildup of pressures that lead to protection; 6) an institution to consider exceptional protection should be advisory (independent of day-to-day trade policymaking), so that it works steadily, free from administrative pressures and exigencies. Requests for protection must be handled openly and transparently, with the findings subject to public scrutiny. Procedures for granting relief through safeguards and similar mechanisms must reflect all interests, including those of consumers, exporters, and users of the product; and 7) the analysis to establish injury must conform to high technical standards. The criteria to consider trade policies must reflect national interests, not those of any particular sector.Economic Theory&Research,Common Carriers Industry,Trade Policy,Environmental Economics&Policies,Payment Systems&Infrastructure,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Trade Policy,Environmental Economics&Policies,Transport and Trade Logistics
Learning of Soil Behavior from Measured Response of a Full Scale Test Wall in Sandy Soil
No full textIn urban deep excavations, instruments are placed to monitor deformations and to control construction and reduce the risk of excessive and potentially damaging deformations. The second author has introduced a new inverse analysis approach that utilizes measured excavation performance to extract the underlying soil behavior. The extracted soil behavior can be used in predicting the behavior of similar excavations. This paper provides a first implementation of this inverse analysis approach to a well instrumented full scale test wall in a sand deposit. A wall consisting of soldier beams with wood lagging was instrumented to study anchored (one and two level tie backs) wall behavior in sandy soil deposits at Texas A&M. Strain gauges, load cells, inclinometers, and settlement points were placed in two sections of the excavation to monitor the excavation behavior. The measured excavation response for the section with two-level tie-backs is used to extract the constitutive model through the inverse analyses approach. The extracted constitutive model is used in predicting the underlying soil behavior for the section with one tie-back level. The predicted behavior of the excavation and its agreement with measurements at the site are discussed in detail
A case report: Ventriculo-peritoneal Shunt in the Presence of Chylous Ascites—Is It Safe?
No full text\ua9 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG. Congenital chylous ascites (CCA) is a rare condition where there is an accumulation of chyle in the peritoneal cavity. Primary CCA due to dysplastic lymphatics is the most common cause in children. CCA discovered on ventriculopertoneal (VP) shunt insertion following previous myelomeningocele repair has only been described in a single paper before with the authors recommending a VP shunt safe to be sited in the presence of CCA. In this paper, we present a case of CCA in a term neonate with a myelomeningocele and an imperforate anus who underwent the siting of a VP shunt with no adverse effect. We provide an alternative hypothesise suggesting the link between raised intra-abdominal pressure caused by the imperforate anus as the aetiological factor in CCA
Pore pressure generation and liquefaction analysis using nonlinear, effective stress-based site response analysis
No full textOpen Restriction set for Item 109954 on 2020-05-12T14:03:02Z with date null by [email protected] Restriction set for Item 109954 on 2020-05-12T14:03:06Z with date null by [email protected] pressure (PWP) generation leading to soil softening and potential liquefaction in sandy soils are pervasive problems during earthquakes. However, our ability to predict the impacts of PWP generation on ground motions and the resulting response spectra are not particularly good. While software is available to perform nonlinear effective stress site response, there are no guidelines for assessing the accuracy of such models. Also, most design codes classify sites susceptible to significant softening as Site Class F and require site-specific ground response analyses. Even if site-specific analyses are performed, many of these codes require that the resulting site-specific acceleration response spectrum not be less than 80% of the code-prescribed spectrum computed using Site Class E based on experience from “total stress” analyses and does not explicitly account for sites where significant PWP increase is likely to occur. Unfortunately, little guidance is available to develop more defensible code commentary.
In this research, cyclic and monotonic shear tests have been collected to evaluate and validate the modified Vucetic and Dobry (1986) PWP generation model coupled with a generalized/Hyperbolic constitutive model (GQ/H+u) implemented in 1D site response analysis code DEEPSOIL. Results indicate that the GQ/H+u model provides reasonable estimates of PWP increase and stress-strain behavior during cyclic shear element tests but, as expected, cannot simulate soil dilation when the excess PWP ratio is high (ru> 0.8).
Available centrifuge tests and field case studies have been simulated to further validate the performance of GQ/H+u model. Again, the GQ/H+u model reasonably approximates PWP generation and shear stress - shear strain response in these cases over a wide range of relative density but cannot simulate soil dilation when ru > 0.8. Despite this limitation, the GQ/H+u model was able to reasonably capture acceleration response at in the centrifuge tests when either of the following criteria were met: (1) computed ru 0.8 and computed maximum shear strain was less than the limit shear strain (γmax <γlimit).
A parametric study of both synthetic and published soil profiles has been performed using effective stress-based, nonlinear site response analysis. The parametric study yielded liquefaction resistances that generally were in excellent agreement with published liquefaction resistance curves (Andrus and Stokoe 2000; Kayen et al. 2013) for Vs1 200 m/s, input motions that exhibit near-fault effects, and cases where soft clay layers underlie the loose, liquefiable sand layers. Each of these conditions are explained and quantified.
Response spectra were developed based on GQ/H+u model, a hybrid method, and code requirements for a number of centrifuge experiments and well-documented field case histories, and these spectra then were compared with measurements to assess the validity of these methods. For cases in which the computed ru 0.8 and γmax 0.4s. In layers/cases where ru > 0.8 and γmax > γlimit, the occurrence of dilation spikes can increase spectral accelerations at both short and long periods, making them larger than the 80% of Site Class E spectral accelerations. Here, analysis results from the GQ/H+u model, as well as results from more sophisticated constitutive models, do not match the measured spectral accelerations, particularly if the maximum spectral velocity (Sv) of the input motion occurs at long periods (T > ~1 second). Until models are better able to capture this response on a consistent basis, an interim approach may be to envelope the GQ/H+u and 80% of Site Class E spectra for use in design.
The effect of PWP generation on response spectra has been investigated through a parametric study, the results of which indicate that a factor of safety against liquefaction triggering (FSliq, computed by the cyclic stress method) < 1.4, commonly corresponds to ru < 0.8. As such, a cyclic stress-based FSliq < 1.4 can be used as a threshold for defining when NL-ES analysis should be conducted at a potentially liquefiable site.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2020-12-01The student, Xuan Mei, accepted the attached license on 2018-11-30 at 12:48.The student, Xuan Mei, submitted this Dissertation for approval on 2018-11-30 at 13:21.This Dissertation was approved for publication on 2018-12-03 at 09:36.DSpace SAF Submission Ingestion Package generated from Vireo submission #13160 on 2019-02-08 at 11:40:38Made available in DSpace on 2019-02-08T18:43:47Z (GMT). No. of bitstreams: 2
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