Yielding around notches in tensile specimens

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Effect of Horizontal Passage Length on Solid Recycle Through a Loop Seal in a Circulating Fluidized Bed

Solid flow through the loop seal of a circulating fluidized bed (CFB) was studied by investigating the effect of the horizontal passage length on solid flow through the loop seal. This was done by investigating the effects of aeration on the inter-particle friction forces, the effect varying horizontal passage lengths had on the overall solid flux around the CFB loop and on the pressure drop across the passage. The division of air flow through the loop seal was also investigated in order to determine how the solids were driven through the loop seal. It was found that for a measurable amount of solid flow to occur, a minimum aeration was required, in excess of the minimum fluidizing velocity of the particles. As horizontal passage length increased the minimum aeration required also increased. As well the maximum obtainable solid flux decreased with increasing passage length due to the increased resistance in the longer passage. The increased resistance to solid flow through the passage was seen in the increasing pressure drop per unit length across the passage, as the passage length increased. This was a result of an area of stationary solids near the end of the horizontal passage that constricted the flow of solids and got larger as the passage length increased. At low solid flow rates the supply chamber aeration was split, such that the velocity of air in the supply chamber or the stand pipe remained below the minimum fluidization velocity with the remaining flow conveying solids through the horizontal passage. At high solid flow rates all of the supply chamber aeration flowed into the horizontal passage along with an amount of air entrained by the solids falling down the standpipe

Analysis of the Implementation of Total Productive Maintenance, Total Quality Management, and Just-In-Time in Pharmaceutical Manufacturing

In the pharmaceutical industry, systems for improving operational effectiveness and efficiency are becoming more and more popular. In this paper, developments in the industry's improvements in operational effectiveness and efficiency have been analyzed. A holistic model is presented which builds the basis for the presented study results. The study includes data gathered from pharmaceutical production sites in surveys in 2004 and 2009. The analysis is divided according to the four sub-systems: Total Productive Maintenance, Total Quality Management, Just-in-Time, and the Management System. For each sub-system, key performance indicators and associated elements (practices and instruments) from 2004 to 2009 are investigated. The data indicates that the industry did make continuous steps towards "Excellence in Operations” between 2004 and 2009. Pharmaceutical companies took control over their former low asset utilization and managed to improve the efficiency of their quality systems; however, they are still far away from having any kind of "continuous flow”, smooth production scheduling or make-to-order manufacturing. It can be said that most of the companies are still working on the effectiveness side rather than focusing on the efficiency sid

Study of Calcination-Carbonation of Calcium Carbonate in Different Fluidizing Mediums for Chemical Looping Gasification in Circulating Fluidized Beds

Chemical looping gasification (CLG) of biomass in a circulating fluidized bed is an excellent option for production of separate streams of hydrogen rich and carbon dioxide rich gases. This process uses H2O (steam) instead of air or oxygen for gasification, and thereby produces high value nitrogen free product gas. An important feature of this process is in-process removal of carbon dioxide from the reaction site by CaO. This allows the reaction to move towards higher yield of hydrogen. Circulating fluidized bed (CFB) provides an ideal reactor configuration for such a looping reaction. A CFB based CLG unit operates somewhat similar to the FCC reactor except that the bubbling bed in the loopseal serves as the gasifier where calcined limestone absorbs carbon dioxide forming calcium carbonate. The riser works as the regenerator of CaCO3, the CO2 sorbent. Thus, the sorbent particles move back and forth between the riser calciner and loopseal carbonizer. To study this process closely and to determine how well the sorbent retains its reactivity through such a cyclical process, an experiment was carried out in a Quartz wool matrix reactor (QWM), which closely simulates the highly expanded ambience of a fast-fluidized bed. An empirical relation was developed for the conversion of calcium carbonate (CaCO3) as a function of temperature and residence time. A simple reaction kinetic model for calcination in presence of N2, CO2 and H2O has been developed and compared. Loss in effectiveness of the sorbent has been studied and another empirical relation was developed for the estimation of extent of carbonation with the number of cycle

An Experimental And Theoretical Investigation Into Airflow Through Air Box Of A Potato-Rock Separator

Velocity and pressure distribution in the air duct system and that over the grate of a potato-rock separator of Alan Equipment, PEI was analysed utilizing computational fluid dynamics. COMSOL software using appropriate boundary conditions was used for rapid analysis of flow through the system. To calibrate the theoretical results velocity, pressure and flow rates were measured on the actual full-scale unit. These tests were carried out using pitot tube, digital manometer and special duct flow measurer. Experimental result was compared with the obtained simulation result. The effect of duct geometry on the velocity distribution through the grate was established through this exercise

Is There an Optimal CO2 Partial Column for Flux Inversions?

The fidelity of flux estimates from an atmospheric inversion depends on the ability of atmospheric transport models to simulate the measured quantity. For species such as CO2, with surface fluxes and a large network of surface measurements, this means correctly simulating the dynamics of the planetary boundary layer (PBL), which is one of the most uncertain aspects of atmospheric transport modeling. In contrast, the simulated total column average mole fraction of CO2 (XCO2) is largely insensitive to simulated PBL dynamics. Therefore, measurements of XCO2 provided by current and future short wave infrared (SWIR) greenhouse gas (GHG) satellites such as GOSAT and the OCO family would seem to be more appropriate to flux inversions, as far as minimizing transport model errors (the "noise") is concerned. Unfortunately, the flux-induced variation of CO2 (the "signal") is the largest within the PBL and smallest in XCO2. Therefore, assimilating XCO2 as opposed to PBL CO2 need not give us the strongest "signal to noise" in flux inversions. Recent work on GOSAT and OCO2 retrievals suggest that SWIR satellite spectra may be used to estimate a lower partial column CO2, which could be assimilated in a flux inversion, instead of XCO2.Here we report on a study to assess whether there is an optimal partial column average CO2, intermediate between PBL CO2 and XCO2, whose assimilation might yield the best signal to noise in flux inversions, where (as before) "signal" is the flux-induced variation and "noise" is the error in transport modeling. We simulate atmospheric CO2 with five different global transport models and a common surface CO2 flux over ten years. We consider the spread across the five models to be a proxy for transport model error (the "noise"), and the common variation of CO2 in all five models to be a proxy for the "signal". We compare these signals and noises at different spatiotemporal scales for different partial column specifications to investigate whether there exists an optimal partial column that has large surface flux-driven variations and yet is relatively insensitive to errors in transport models. Finally, we comment on the feasibility of estimating such a partial column from current and future SWIR GHG satellites in the light of recent work on vertically resolved CO2 from current SWIR GHG satellites

Global atmospheric CO₂ inverse models converging on neutral tropical land exchange, but disagreeing on fossil fuel and atmospheric growth rate

We have compared a suite of recent global CO₂ atmospheric inversion results to independent airborne observations and to each other, to assess their dependence on differences in northern extratropical (NET) vertical transport and to identify some of the drivers of model spread. We evaluate posterior CO₂ concentration profiles against observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) aircraft campaigns over the mid-Pacific in 2009–2011. Although the models differ in inverse approaches, assimilated observations, prior fluxes, and transport models, their broad latitudinal separation of land fluxes has converged significantly since the Atmospheric Carbon Cycle Inversion Intercomparison (TransCom 3) and the REgional Carbon Cycle Assessment and Processes (RECCAP) projects, with model spread reduced by 80 % since TransCom 3 and 70 % since RECCAP. Most modeled CO₂ fields agree reasonably well with the HIPPO observations, specifically for the annual mean vertical gradients in the Northern Hemisphere. Northern Hemisphere vertical mixing no longer appears to be a dominant driver of northern versus tropical (T) annual flux differences. Our newer suite of models still gives northern extratropical land uptake that is modest relative to previous estimates (Gurney et al., 2002; Peylin et al., 2013) and near-neutral tropical land uptake for 2009–2011. Given estimates of emissions from deforestation, this implies a continued uptake in intact tropical forests that is strong relative to historical estimates (Gurney et al., 2002; Peylin et al., 2013). The results from these models for other time periods (2004–2014, 2001–2004, 1992–1996) and re-evaluation of the TransCom 3 Level 2 and RECCAP results confirm that tropical land carbon fluxes including deforestation have been near neutral for several decades. However, models still have large disagreements on ocean–land partitioning. The fossil fuel (FF) and the atmospheric growth rate terms have been thought to be the best-known terms in the global carbon budget, but we show that they currently limit our ability to assess regional-scale terrestrial fluxes and ocean–land partitioning from the model ensemble

Effect of magnetic nanoparticles on the nematic-smectic-A phase transition

Recent experiments on mixed liquid crystals have highlighted the hugely significant role of ferromagnetic nanoparticle impurities in defining the nematic-smectic-A phase transition point. Structured around a Flory-Huggins free energy of isotropic mixing and Landau-de Gennes free energy, this article presents a phenomenological mean-field model that quantifies the role of such impurities in analyzing thermodynamic phases, in a mixture of thermotropic smectic liquid crystal and ferromagnetic nanoparticles. First we discuss the impact of ferromagnetic nanoparticles on the isotropic-ferronematic and ferronematic-ferrosmectic phase transitions and their transition temperatures. This is followed by plotting and discussing various topologies in the phase diagrams. Our model results indicate that there exists a critical concentration of nanoparticle impurities for which the second order N-SmA transition becomes first order at a tricritical point. Calculations based on this model show remarkable agreement with experiment

Passive Transdermal Systems Whitepaper Incorporating Current Chemistry, Manufacturing and Controls (CMC) Development Principles

In this whitepaper, the Manufacturing Technical Committee (MTC) of the Product Quality Research Institute has updated the 1997 Transdermal Drug Delivery Systems Scale-Up and Post Approval Change workshop report findings to add important new product development and control principles. Important topics reviewed include ICH harmonization, quality by design, process analytical technologies, product and process validation, improvements to control of critical excipients, and discussion of Food and Drug Administration’s Guidance on Residual Drug in Transdermal and Related Drug Delivery Systems as well as current thinking and trends on in vitro–in vivo correlation considerations for transdermal systems

National CO2 budgets (2015–2020) inferred from atmospheric CO2 observations in support of the Global Stocktake

Accurate accounting of emissions and removals of CO2 is critical for the planning and verification of emission reduction targets in support of the Paris Agreement. Here, we present a pilot dataset of country-specific net carbon exchange (NCE; fossil plus terrestrial ecosystem fluxes) and terrestrial carbon stock changes aimed at informing countries’ carbon budgets. These estimates are based on "top-down" NCE outputs from the v10 Orbiting Carbon Observatory (OCO-2) modeling intercomparison project (MIP), wherein an ensemble of inverse modeling groups conducted standardized experiments assimilating OCO-2 column-averaged dry-air mole fraction (XCO2) retrievals (ACOS v10), in situ CO2 measurements, or combinations of these data. The v10 OCO-2 MIP NCE estimates are combined with "bottom-up" estimates of fossil fuel emissions and lateral carbon fluxes to estimate changes in terrestrial carbon stocks, which are impacted by anthropogenic and natural drivers. These flux and stock change estimates are reported annually (2015–2020) as both a global 1° × 1° gridded dataset and as a country-level dataset. Across the v10 OCO-2 MIP experiments, we obtain increases in the ensemble median terrestrial carbon stocks of 3.29–4.58 PgCO2 yr-1 (0.90–1.25 PgC yr-1). This is a result of broad increases in terrestrial carbon stocks across the northern extratropics, while the tropics generally have stock losses but with considerable regional variability and differences between v10 OCO-2 MIP experiments. We discuss the state of the science for tracking emissions and removals using top-down methods, including current limitations and future developments towards top-down monitoring and verification systems