PM Processes Research Articles

Modeling study on the air quality impacts from emission reductions and atypical meteorological conditions during the 2008 Beijing Olympics

Understanding of the relative impacts of emission reductions and meteorological variations on air quality during the 2008 Beijing Olympics has an important policy implication. In this work, detailed process analyses and sensitivity simulations under different emission and meteorology scenarios were conducted using CMAQ and the Process Analysis tool to quantify the air quality benefits from emission reductions and meteorological variations in August 2008. The results indicate that emission-driven changes dominate surface concentration reductions of SO2, NO2, VOCs, daily maxima O3 and PM2.5 by −11% to −83%. The effect of meteorology-driven changes on species concentrations can be either ways (by −46% to 105%) at different locations. The dominant processes contributing to O3, PM2.5, SO42−, NO3−, and secondary organic aerosol (SOA) are identified. Gas-phase chemistry is a major process for O3 production, and PM processes are dominant sources for PM2.5 in the planetary boundary layer (PBL). The reduced emissions weaken the source contributions of gas-phase chemistry to O3 and those of PM processes to PM2.5, with weaker vertical mixing processes and horizontal transport in the PBL. Compared with 2007, 2008 has a higher humidity, lower temperature and more precipitation that benefit O3 reduction within the PBL, and a weaker vertical mixing that disbenefits reductions of all pollutants concentrations. Stronger process contributions of cloud processes (e.g., below- and in-cloud scavenging, and wet deposition) in 2008 help reduce concentrations of PM2.5, NO3−, and SOA, but they (e.g., aqueous-phase chemistry) enhance surface SO42− concentrations. Smaller process contributions of aerosol processes help reduce the concentrations of SOA and SO42− but enhance NO3− and PM2.5 in lower layers (1–6) due to the evaporation of NO3−. The ratios of PH2O2/PHNO3 increase under the controlled simulation, indicating that the emission control actions enforced during the 2008 Olympics weakened the sensitivity of O3 chemistry to VOC emissions in urban areas.

Examining Collaborative Dialogue Among Couples

Prospective memory is a key ability required for independent living and consistent with Einstein and McDaniel (1990) , we hypothesized that social partners can serve as useful external memory aids, particularly in middle and late life when these abilities may wane. We employed the Virtual Week (Rendell & Craik, 2000) task in a novel way to investigate the contribution of social partners to the prospective memory process. We examined the collaborative interactions of 11 middle-aged (M = 52.15 years; n = 5) and older (M = 75.24 years; n = 6) married dyads. The dialogue of collaborating partners reflected important PM processes (e.g., encoding, monitoring, tutoring). Age group differences favored middle-aged adults, and preliminary evidence suggested a link between collaborative dialogue and PM performance. Further investigation can determine how social partners can be used strategically to improve prospective memory outcomes.

Brain Activation Related to Combinations of Gaze Position, Visual Input, and Goal-Directed Hand Movements

Humans reach to and acquire objects by transforming visual targets into action commands. How the brain integrates goals specified in a visual framework to signals into a suitable framework for an action plan requires clarification whether visual input, per se, interacts with gaze position to formulate action plans. To further evaluate brain control of visual-motor integration, we assessed brain activation, using functional magnetic resonance imaging. Humans performed goal-directed movements toward visible or remembered targets while fixating gaze left or right from center. We dissociated movement planning from performance using a delayed-response task and manipulated target visibility by its availability throughout the delay or blanking it 500 ms after onset. We found strong effects of gaze orientation on brain activation during planning and interactive effects of target visibility and gaze orientation on movement-related activation during performance in parietal and premotor cortices (PM), cerebellum, and basal ganglia, with more activation for rightward gaze at a visible target and no gaze modulation for movements directed toward remembered targets. These results demonstrate effects of gaze position on PM and movement-related processes and provide new information how visual signals interact with gaze position in transforming visual inputs into motor goals.

Prospective memory and working memory: Asymmetrical effects during frontal lobe TMS stimulation

The role of working memory (WM) for the realization of an intended action (prospective memory, PM) has been debated in recent neuropsychological literature. The present study aimed to assess whether WM and PM share resources or are, alternatively, two distinct mechanisms. A verbal task was used, which manipulated the cognitive demand of both WM and PM dimensions on an event-based prospective task. Transcranial magnetic stimulation (TMS) was also employed to clarify the causal contribution of frontal areas previously related to WM, to the PM process. The prospective task required the participant to respond whenever a word appeared which had been presented before the beginning of the task. Two ongoing tasks were administered: an updating WM task (in two conditions of medium and high WM demands) and a lexical decision task (representing a low WM demand). In the first two experiments, higher PM demand affected WM only at higher loads, but the PM load effect was independent of WM, showing asymmetrical behavioural effects. In the third experiment, single pulse TMS was applied to left and right dorsolateral prefrontal cortices. When applied to the experimental sites, stimulation increased error rates of the PM task, while the effect was only marginal in the WM task. The effect was bilateral, since there was no difference between left and right stimulation sites. These findings demonstrated, from both behavioural and neurofunctional perspectives, that WM and PM processes are not based on the same memory system, but PM may require WM resources at high demand.

Probing into regional O3 and particulate matter pollution in the United States: 2. An examination of formation mechanisms through a process analysis technique and sensitivity study

Following a comprehensive model evaluation in part 1, this part 2 paper describes results from 1 year process analysis and a number of sensitivity simulations using the Community Multiscale Air Quality (CMAQ) modeling system aimed to understand the formation mechanisms of O3 and PM2.5, their impacts on global environment, and implications for pollution control policies. Process analyses show that the most influential processes for O3 in the planetary boundary layer (PBL) are vertical and horizontal transport, gas‐phase chemistry, and dry deposition and those for PM2.5 are primary PM emissions, horizontal transport, PM processes, and cloud processes. Exports of O3 and Ox from the U.S. PBL to free troposphere occur primarily in summer and at a rate of 0.16 and 0.65 Gmoles day−1, respectively. In contrast, export of PM2.5 is found to occur during all seasons and at rates of 25.68–34.18 Ggrams day−1, indicating a need to monitor and control PM2.5 throughout the year. Among nine photochemical indicators examined, the most robust include PH2O2/PHNO3, HCHO/NOy, and HCHO/NOz in winter and summer, H2O2/(O3 + NO2) in winter, and NOy in summer. They indicate a VOC‐limited O3 chemistry in most areas in winter, but a NOx‐limited O3 chemistry in most areas except for major cities in April–November, providing a rationale for nationwide NOx emission control and integrated control of NOx and VOCs emissions for large cities during high O3 seasons (May–September). For sensitivity of PM2.5 to its precursors, the adjusted gas ratio provides a more robust indicator than that without adjustment, especially for areas with insufficient sulfate neutralization in winter. NH4NO3 can be formed in most of the domain. Integrated control of emissions of PM precursors such as SO2, NOx, and NH3 are necessary for PM2.5 attainment. Among four types of VOCs examined, O3 formation is primarily affected by isoprene and low molecular weight anthropogenic VOCs, and PM2.5 formation is affected largely by terpenes and isoprene. Under future emission scenarios, surface O3 may increase in summer; surface PM2.5 may increase or decrease. With 0.71°C increase in future surface temperatures in summer, surface O3 may increase in most of the domain and surface PM2.5 may decrease in the eastern U.S. but increase in the western U.S.

Global Competitiveness of Powder Metallurgy Part Manufacturing in North Central Pennsylvania

Provided in this report is information summarizing the global competitive dynamics and pressures on the PM part manufacturing industry in north central Pennsylvania. Information is provided about the geographic/economic region in which the industry operates. A brief description of PM manufacturing materials and processes is presented. Then, an analysis is reported of the economic and workforce structure of PM part manufacturing industry in north central Pennsylvania. Last, evidence of competitive forces affecting the industry is drawn from structured face-to-face and telephone meetings, gleaned during plant tours and over informal lunches, linked by following trends and themes in documents, and captured in confidences revealed in unstructured personal conversations. These competitive forces are summarized around five themes: the threat of entry of new competitors; bargaining power of customers; bargaining power of suppliers; the threat (and opportunity) posed by substitute products; and the nature of competitive rivalry within the PM part manufacturing industry. The kernel of competition in the PM part manufacturing industry is summarized in the following simple statements:• The north central region of Pennsylvania is an economic region that is the locus of PM part manufacturing industry activity in the United States. It generates much economic good in the region for individuals and institutions. The industry is both a jewel and a bellwether for the Pennsylvania economy. The competitiveness of the PM part industry is a lynchpin economic driver in Pennsylvania, in general, and the north central region, in particular.• The PM part manufacturing industry brings unique and specialized manufacturing know–how from Pennsylvania to the world through its economic and technological contribution and potential.• New competitors can enter the industry at the low end with modest capital and knowledge of PM parts manufacturing. However, to play at the high end, new market entrants require deeper pockets. • Foreign involvement and ownership are diffusing around the world the specialized knowledge and human capital that formerly was localized to north central Pennsylvania. Competition is not local any more. It is global.• PM part manufacturers compete aggressively and almost solely on the basis of price.• Poor understanding and inaccurate perceptions held by customers about the materials, processes, and end-products of PM part manufacturing affect the competitive position of the industry.• The PM industry deals with a small number of large suppliers and customers who have the power to dictate the ability of PM part manufacturing firms to cover their costs and make a profit. • The PM part manufacturing industry is small relative to the entire manufacturing sector and, in particular, within the fabricated metal product manufacturing subsector. Just on these scale factors alone, opportunities probably are large for capturing metal fabrication opportunities from other industries or for finding ways to create complementary products with other metal fabrication industries.• Competition among firms in the fabricated metal products industry for PM part markets is intense. The struggle for the connecting rod market between the PM part manufacturing industry and the steel forging industry is a case in point.• The automotive market is a dominant force in the PM part manufacturing industry. The culture of supplier discipline followed by the automobile industry guarantees a cost–frugal, price–competitive environment for PM part manufacturing.• Metal commodity prices are volatile and rising, adding risk, uncertainty, and rising costs to metal powder inputs to PM part manufacturing. • Mistakes made in the past by incorrectly specifying PM for parts for which PM is not suited led to credibility problems which still affect the competitive stance of the industry.• The PM part manufacturing industry has difficulty recruiting workers with skills adaptable to the industry. Part of this problem is due to deficiencies in the pipeline for skill creation; some of this problem lies with the relative geographic isolation of the industry in north central Pennsylvania.• PM part manufacturing firms compete vigorously with each other, almost entirely on the basis of price, but rarely against other processes.

Degradation and the kinetics of binder removal

Manufacturing large anodes for aluminium smelting by PM processes is far from simple, and efficient binder removal from the green body is a primary requirement…

Friction and wear behaviour of sintered steels submitted to sliding and abrasion tests

Fe–C–Mo and Fe–C–Cr steels were sintered by PM processes carried out using different values of temperature and pressure, leading to different microstructures and density values. Flat specimens were submitted to tribological tests in order to evaluate their behaviour under both dry sliding and abrasive wear conditions. A flat-on-cylinder tribometer was used for the sliding tests, while a micro-scale ball cratering device was used for the abrasion tests. The dry sliding wear resistance of the PM steels was mainly influenced by the composition and sintering conditions. In this regard, the best behavior was observed for the more hardenable Fe–C–Mo steels with higher Mo content, sintered under conditions giving rise to bainitic microstructures. A determining role was also played by the porosity content and pore shape: reduction in porosity (obtained by increasing the sintering temperature and the compacting pressure), as well as an increase in pore roundness, led to a significant improvement in the resistance to sliding wear. A mild oxidative wear regime were observed for all the sintered steels under relatively low values of the applied load, while an increase of the applied load led to a delamination wear regime. The resistance to abrasive wear was low for all the tested steels, irrespective of composition and sintering cycle.

Sources and elemental composition of ambient PM 2.5 in three European cities

Source apportionment of urban fine particle mass (PM 2.5) was performed from data collected during 1998–1999 in Amsterdam (The Netherlands), Erfurt (Germany) and Helsinki (Finland), using principal component analysis (PCA) and multiple linear regression. Six source categories of PM 2.5 were identified in Amsterdam. They were traffic-related particles (30% of the average PM 2.5), secondary particles (34%), crustal material (7%), oil combustion (11%), industrial and incineration processes (9%), and sea salt (2%). The unidentified PM 2.5 fraction was 7% on the average. In Erfurt, four source categories were extracted with some difficulties in interpretation of source profiles. They were combustion emissions related to traffic (32%), secondary PM (32%), crustal material (21%) and industrial processes (8%). In Erfurt, 3% of PM 2.5 remained unidentified. Air pollution data and source apportionment results from the two Central European cities were compared to previously published results from Helsinki, where about 80% of average PM 2.5 was attributed to transboundary air pollution and particles from traffic and other regional combustion sources. Our results indicate that secondary particles and local combustion processes (mainly traffic) were the most important source categories in all cities; their impact on the average PM 2.5 was almost equal in Amsterdam and Erfurt whereas, in Helsinki, secondary particles made up for as much as half of the total average PM 2.5.

Accurate modelling of PM processes by back propagation neural networks

Accurate modelling of PM processes by back propagation neural networks

Tailored PM processes for highly loaded applications: V.Arnhold et al. (GKN Sinter Metals, Germany.)

Tailored PM processes for highly loaded applications: V.Arnhold et al. (GKN Sinter Metals, Germany.)

Calculating Project Management's Return on Investment

This paper describes a procedure that can help managers measure their return on investment for project management (PM/ROI). Current PM processes and practices of 38 different companies and government agencies in 4 different industries or application areas were quantitatively examined. A PM benchmarking procedure was developed and used to assess the PM process maturity of these different organizations. A 5-level Berkeley PM process maturity model is introduced. This information is used to measure the relative sophistication and maturity of different organizations and industries.

Powders and Processes for High Performance PM Steels

Development of new PM materials and processes has led to an increased use of PM machine components. Due to their good mechanical properties it is possible for them to fulfil the demand for high performance applications such as connecting rods, highly loaded gear box parts, transmission gears, etc. The competitive advantage of PM is primarily the net shape achievable with a minimum of operations. The dimensional tolerances are therefore of the greatest importance; especially for high strength materials which cannot be sized, the dimensions must be very close to those required after sintering. This has led to the development of powders such as the Distaloy grades or bonded powder mixes such as Starmix. The objective of these powder types is to reduce the range of alloying composition and thereby improve tolerances. This paper describes some high strength materials and the influence of processing parameters on their dimensional tolerances. In order to meet the demanding requirements of new applications it is shown that the advantages of diffusion alloyed powders, prealloyed powders, and bonded powder mixes must be used. PM/0572

Energy Requirements of Structural Components: Powder Metallurgyv.Other Production Processes

AbstractOn the basis of increasing problems of energy availability and costs, the energy requirements for producing structural components by various possible production processes have been estimated. Also the energy requirements in raw material preparation (iron powders, cast iron, construction steels) have been taken into account. The production techniques considered are cold forming, hot forming (or closed die forging), and machining (turning, reaming, milling). For each kind of machining and for various materials the energy requirements corresponding to removal of unit weight or unit volume have been calculated. The comprehensive comparison between PM processes and other production processes has been made considering variable relative amounts of swarfs. The data show that the sintered components are generally less energy consuming than the equivalent ones produced by competitive production techniques. This favourable position of PM can be improved still more by increasing the efficiency of present sint...

Raw Material and Energy Conservation in Production of Sintered PM Parts

It can be regarded as proven that the PM production of structural parts for the processing industry is a forming method involving minimum utilization of energy and material. In the present paper, data on energy consumption are examined using industrial examples for the individual stages in the process. These stages are the production of the raw material, shaping, sintering, and secondary forming. On the subject of single and double sintering, two examples are given in each case of the economies attainable through the use of PM processes, and some ideas for further reductions in energy consumption are put forward. PM/0239