scholarly journals Study on Double-Layer Ignition Sintering Process Based on Autocatalytic Denitrification of Sintering Layer

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 33
Author(s):  
Benjing Shi ◽  
Junying Wan ◽  
Tiejun Chen ◽  
Xianlin Zhou ◽  
Yanhong Luo ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Fuel Consumption ◽  
Double Layer ◽  
Solid Fuel ◽  
Ignition Time ◽  
Environmental Benefits ◽  
Time Interval ◽  
Sintering Process ◽  
The Impact

An efficient sintering process was proposed based on the autocatalytic denitrification of the sintered ore. The catalytic denitrification of sintered ore, the effect of double-layer ignition sintering process on the emission reduction in nitrogen oxides, and the impact on the quality of sintered ore were studied. The results showed that the catalyzed reduction of NO with sinter ore as a catalyst has a significant effect; when the airspeed reaches 3000 h−1, the temperature is 500 °C, and the conversion rate of NO can reach 99.58%. The sinter yield of double-layer ignition sintering is increased, solid fuel consumption is slightly reduced, falling strength is slightly increased, and drum strength is slightly decreased. Under the conditions of layer height proportion of 320/400 mm (lower/upper) and ignition time interval of 10 min, the yield, drum strength, shatter strength, and solid fuel consumption reached 61.60%, 54.82%, 46.75%, and 69.55%, respectively. NOx concentration under the 16% baseline oxygen content (c(NOx)’) in the flue gas of double-layer ignition sintering is reduced to a certain extent, and the generation time of NOx is greatly shortened. The double-layer ignition sintering process can reduce the emission of nitrogen oxides in the sintering process under the condition of guaranteeing the quality of sinter, which has great economic and environmental benefits.

scholarly journals MATERIAL AND THERMAL ANALYSIS OF LASER SINTERTED PRODUCTS

2013 ◽  
Vol 7 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Radovan Hudák ◽  
Martin Šarik ◽  
Róbert Dadej ◽  
Jozef Živčák ◽  
Daniela Harachová
Keyword(s):  
Thermal Analysis ◽  
Heat Stress ◽  
Thermal Stresses ◽  
Processing Parameters ◽  
Sintering Process ◽  
Input Processing ◽  
Thermal Simulations ◽  
The Impact ◽  
Selection Of

Abstract Thermal analysis of laser processes can be used to predict thermal stresses and consequently deformation in a completed part. Analysis of temperature is also the basic for feedback of laser processing parameters in manufacturing. The quality of laser sintered parts greatly depends on proper selection of the input processing parameters, material properties and support creation. In order to relatively big heat stress in the built part during sintering process, the thermal simulation and thermal analysis, which could help better understand and solve the issue of parts deformations is very important. Main aim of presented work is to prepare input parameters for thermal simulations by the use of RadTherm software (Thermoanalytics Inc., USA), directly during the sintering process and after the process and find out the impact of the heat stress on a final shape and size of the prototype. Subsequently, an annealing process of constructed products after DMLS could be simulated and specified.

The Impact of Employing Different Quality PA2200 Powder Grades to Shrinkage on Sintered Part in Selective Laser Sintering Process

2015 ◽  
Vol 789-790 ◽  
pp. 126-130
Author(s):  
W.A.Y. Yusoff ◽  
D.T. Pham ◽  
K.D. Dotchev
Keyword(s):  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Sintering Process ◽  
Melt Flow Rate ◽  
Input Material ◽  
Low Degree ◽  
Powder Properties ◽  
Plastic Parts ◽  
The Impact

One of the challenges which Laser Sintering faces is the Rapid Manufacturing of plastic parts with good consistent quality. This is due to the fact that plastic powder properties deteriorate during the long periods of time through the LS building and cooling cycles. This paper presents an experimental study of the deterioration or ageing of PA12 powder properties in the LS process. The influences of different grades of recycled PA12 powders are investigated. The main aim of this research is to develop a methodology of controlling the input material properties that will ensure consistent and good quality of the fabricated parts. From the experiment it was found that PA12 powder with high melt flow rate, low melting temperature, low glass transition temperature and low degree of crystallization temperature could improve the sintering process to produce a good Laser Sintering (LS) parts with lower shrinkage rate.

scholarly journals Impact of Tourism Development on the Quality of Life: A case study of Perhentian Island, Malaysia

2020 ◽  
pp. 22-37
Author(s):  
Aleff Omar Shah Nordin ◽  
Fathilah Ismail ◽  
Nurain Yasmin Mohd Jamal
Keyword(s):  
Quality Of Life ◽  
Local Community ◽  
Negative Impact ◽  
Negative Relationship ◽  
Tourism Development ◽  
Economic Cost ◽  
Economic Benefits ◽  
Environmental Benefits ◽  
The Impact

The purpose of this research was to identify the perceptions of the local community toward tourism development impacts on Perhentian Island. Specifically, the research examined the local community’s perceptions of socio-cultural impacts, economic impacts, and environmental impacts of tourism development. The research also examined the relationship between the impacts of tourism development on the local community’s quality of life (QOL). This research was conducted using a quantitative approach by obtaining responses from 272 local community respondents on Perhentian Island. A household survey based on purposive sampling techniques was conducted to select a suitable sample. The findings of the study revealed that the positive impacts of tourism development outweighed the negative impact. Based on local community perceptions, they believed that tourism development improved their quality of life. This study also finds the impact of social-cultural benefit, economic benefits, economic cost, and environmental benefits have a significant relationship with quality of life. However, there is a negative relationship between the impact of social-cultural cost and environment cost on the quality of life. The findings of this study are important for planners and developers in planning strategic and sustainable tourism development on tourism destinations.

scholarly journals Utilização de filtro intermitente de areia como pós-tratamento de esgoto doméstico – estudo da taxa de aplicação superficial

2019 ◽  
Vol 1 (47) ◽  
pp. 95
Author(s):  
Robson Arruda Dos Santos ◽  
Gilson Barbosa Athayde Junior
Keyword(s):  
Low Cost ◽  
Application Rate ◽  
Environmental Benefits ◽  
Sand Filters ◽  
Treatment Unit ◽  
Sand Filter ◽  
Main Research ◽  
Application Rates ◽  
The Impact

<p class="Normal1">This research is the study of surface application rate for intermittent sand filter sizing, with emphasis to its constructive aspect. It is a design parameter set by the NBR 13969/1997 like the relation between the flow of sewage and surface area of a treatment unit. We examined the main research projects that studied the use of sand filter as post-treatment sewage, highlighting the superficial application rates used in these studies, comparing them with the recommendations of the Brazilian standard that deal with it. The results show that the NBR 13969/97 recommends a lower value to those obtained by Brazilian and foreigner researchers, and regarding Brazilian research, the value of the standard (100 L / m².dia) is always below the rates evaluated. Thus, we highlight the need to update the NBR 13969/97, for that would meet the actual demand for building sand filters, reactor treating of low cost of construction and maintenance, and good removal efficiency of organic matter and nitrification . The environmental benefits are indisputabl and the improvement of the quality of the effluent decreases the impact on water bodies and soil.</p>

scholarly journals CALCULATION OF THE AMOUNT OF HEAVY METALS ENTERING TO THE NEAR-MOTORWAYS GEOSYSTEMS WITH VEHICLE EMISSIONS

2019 ◽  
pp. 20-23 ◽  
Author(s):  
O. Halahan ◽  
N. Korogoda
Keyword(s):  
Heavy Metals ◽  
Fuel Consumption ◽  
Traffic Flow ◽  
Vehicle Emissions ◽  
Time Interval ◽  
Primary Field ◽  
Model Calculations ◽  
Adverse Weather ◽  
Different Types ◽  
The Impact

The article presents the method of obtaining data on the amount of heavy metals (HM), which enter to the near-motorways geosystems with vehicle emissions, with their refinement in accordance with the natural and anthropogenic features of the territory. Firstly, the model calculations take into account the intensity of the impact of the emission source, which depends on the parameters of the traffic flow. To clarify the amount of fuel consumed and, the emissions, as a result, were proposed: indicator Рf,, that defining part of cars, which used different types of fuel in a transport group. The need for this indicator is determined by the fact that different types of fuel have a varied spectrum of impurities in the exhaust gases, as a result of which they are sources of emission of various heavy metals. The next corrective indicator is Рf (age m), which determines the part of cars with different periods of use, because the amount of fuel used depends on it. The “refined” data thus obtained allows us to calculate the amount of heavy metals that “delivers” the traffic flow in a section of a highway during a certain period of time. Secondly, the methodology takes into account the natural conditions of the territory, which determine the spatial characteristics of the primary field of pollution. Because the natural features of the territory also affect changes in fuel consumption. In accordance with this, a number of coefficients are introduced in the calculation methods. Orographic coefficients allow taking into account the differences in fuel consumption by the traffic flow on the road sections with different absolute heights (Кa.h.) and the slope of the roadway (Кsl). Climatic “corrective” coefficients make it possible to clarify the additional fuel consumption arising from the operation of a vehicle on days with low temperatures (coefficient Кt) and days with adverse weather conditions (coefficient Кex). It will be possible to talk about the estimated amount of fuel consumed and, as a consequence, the emissions of heavy metals that form the primary field of contamination. The proposed approach allows determining the degree of influence of motor transport to the near-motorways geosystems and is part of a general algorithm that describes the formation of actual level of contamination in the soil of near-motorways geosystems by heavy metal compounds. The actual level of contamination, in the proposed algorithm, is proposed to be defined as the difference between the volumes of HM, which were introduced into the soil of geosystems for a certain period of time and taken out of its limits and / or excluded from migration flows during the same time interval.

scholarly journals The Impact of Psychopathology Associated With Childhood Trauma on Quality of Life in Portuguese Adolescents: A Two-Wave Longitudinal Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Ricardo Pinto ◽  
Maria Vieira De Castro ◽  
Laura Silva ◽  
Inês Jongenelen ◽  
Angela Maia ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Social Support ◽  
Childhood Adversity ◽  
Moderated Mediation ◽  
Mediating Effect ◽  
Mediation Effect ◽  
Time Interval ◽  
The Impact ◽  
Portuguese Adolescents

Introduction: The aim of this study was to explore the mediating effect of psychopathology between childhood adversity and trauma and quality of life (QOL) in adolescents. The second aim of the study was testing the moderation by social support of this mediation effect.Methods: Self-reports of childhood adversity and trauma, QOL, social support, and psychopathology were collected from 150 Portuguese adolescents' who had been exposed to at least one traumatic event or one childhood adversity (Mage = 16.89, SD = 1.32). The surveys were administered at two time points with an approximate time interval of 1 year.Results: Indirect effects were observed for depression (B = −0.33, CI [−0.62, −0.11]), somatization (B = −0.52, CI [−0.82, −0.23]), and post-traumatic stress symptoms (PTSS) (B = −0.23, CI [−0.45, −0.01]), but not for anxiety (B = 0.20, CI [−0.08, 0.50]). A moderated mediation was found between social support and depression (B = −0.10, CI [−16, −0.04]), and PTSS (B = 0.03, CI [−0.1, −0.05]), but not for somatization (B = −0.02, CI [−0.8, 0.05]).Conclusions: We found that depression and somatization were strong mediators of the relationship between adversity/trauma and QOL, whereas PTSS was moderately mediated this relationship. Anxiety did not mediate this relationship. The moderated-mediation effect of social support was only found for depression and PTSS. The improvement of QOL in adolescents exposed to childhood adversity and trauma should include the assessment of psychopathology symptoms and social support, with the aim of identifying risk and protective factors.

scholarly journals A study of hydrogen fuel impact on compression ignition engine performance

2018 ◽  
Vol 234 ◽  
pp. 03001 ◽  
Author(s):  
Evgeni Dimitrov ◽  
Boyko Gigov ◽  
Spas Pantchev ◽  
Philip Michaylov ◽  
Mihail Peychev
Keyword(s):  
Carbon Dioxide ◽  
Nitrogen Oxides ◽  
Fuel Consumption ◽  
Diesel Fuel ◽  
Carbon Dioxide Concentration ◽  
Hydrogen Gas ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Exhaust Gases ◽  
The Impact

In this paper, a dual-fuel compression ignition engine test bench is presented. In hydrogen-diesel fuel co-combustion conditions, the engine parameters are determined – performance: effective torque, effective power and mean effective pressure; fuel economy: fuel consumption and specific fuel consumption; toxicity: carbon monoxide, carbon dioxide, nitrogen oxides, hydrocarbons, and smoke emissions (opacity). The impact of hydrogen-diesel fuel mass ratio on the performance, toxicity and economy of the engine is studied by obtaining a series of hydrogen-diesel fuel ratio variation characteristics at constant engine speed and load. Improvement of the economical parameters of the engine and reduction of carbon dioxide concentration in exhaust gases is detected under operation with hydrogen gas fuel. Significant reduction of the exhaust gases opacity is observed. It is not clear what the impact of the quantity of hydrogen, injected in the engine, on the concentration of nitrogen oxides in the exhaust gases is.

scholarly journals Assessment of the Method of Merging Landing Aircraft Streams in the Context of Fuel Consumption in the Airspace

2021 ◽  
Vol 13 (22) ◽  
pp. 12859
Author(s):  
Anna Kwasiborska ◽  
Jacek Skorupski
Keyword(s):  
Air Pollution ◽  
Fuel Consumption ◽  
Traffic Safety ◽  
Negative Impact ◽  
Waiting Times ◽  
Air Traffic ◽  
Civil Aviation ◽  
Entry Points ◽  
The Impact

The most important directions in the field of sustainable development of air transport concern increasing the capacity of airports and improving the global civil aviation system, improving air traffic safety, and developing procedures to optimize the operation of the aviation system. An important area is environmental protection and measures to minimize the negative impact of civil aviation activities on the environment. Air traffic and the operation of airports generate adverse environmental effects, including greenhouse gas emissions, air pollution, and noise emissions. Due to the high intensity of aircraft maneuvers, the authors analyzed aircraft traffic in the area approaching the airport. It is essential to correctly line up for aircraft reporting from different entry points to the approach area to avoid waiting for landing. Misalignment of landing aircraft negatively impacts airport capacity, increases fuel consumption through more prolonged waiting times in space, and directly impacts air pollution. There are different ways to organize landing aircraft flows and other ways to merge these flows. The article aims to assess the method of combining the streams of landing aircraft and estimate the impact of such an organization on the increased fuel consumption of aircraft and thus on air pollution. The authors proposed a measure for assessing the quality of the landing queue, which was defined as the increase in flight time of aircraft in the approach area in relation to the nominal time, which was adopted as minimization. In order to obtain the results of research works, a model using a Petri net was developed, allowing for flexible mapping of concurrent processes and their effect analysis. Various methods of combining the streams of landing aircraft have been adopted: three-stage, two-stage, and single-stage. Then, simulation experiments were carried out, allowing the determination of whether the method of combining the streams of landing planes has an impact on the quality of the landing queue measured with the proposed index. The obtained results of the assessment can be used to estimate the increased fuel consumption of the aircraft.

scholarly journals Influence of the quality of fuel atomization on the emission of exhaust gases toxic components of combustion engines

2015 ◽  
Vol 36 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Antoni Jankowski ◽  
Mirosław Kowalski
Keyword(s):  
Nitrogen Oxides ◽  
Droplet Diameter ◽  
Combustion Process ◽  
Combustion Engines ◽  
Exhaust Gases ◽  
Fuel Droplets ◽  
Fuel Atomization ◽  
The Rich ◽  
The Impact

Abstract The paper contains analysis of the impact on the quality of the fuel spray of droplets on the number and the value of the surface area of the droplets that have a direct impact on the efficiency of the combustion process. It presents a change in the level of toxic exhaust emissions with an increase in the so-called. Sauter Mean Diameter (SMD) of fuel droplets. The presented figures show that the increase in the average droplet diameter SMD in particular causes an increase of toxic exhaust gases emissions, i.e. mainly nitrogen oxides NO, carbon monoxide CO, hydrocarbons HC and Particulate Matter (PM). This tendency is not constant, because it is changing according to changes of the coefficient of equivalence Φ. For example, emissions of nitrogen oxides for the lean mixtures (Φ <1), with an increase in average droplet diameter increases, while now for the rich mixtures (Φ> 1), this trend is significantly changed, i.e. the level of this emission decreases.

scholarly journals The Life Cycle of Biodegradable and Compostable Packaging from the Perspective of Developing a Sustainable Bioeconomy

2021 ◽  
Author(s):  
Gabriela Iuliana Paraschiv (Ganea) ◽  
◽  
Stefania-Rodica Hubel (Angel) ◽  
Elena Condrea ◽  
◽  
...  
Keyword(s):  
Life Cycle ◽  
Environmental Performance ◽  
Evaluation Process ◽  
Life Cycle Stage ◽  
Environmental Benefits ◽  
Use Of Resources ◽  
Decomposition Time ◽  
Environmental Performance Assessment ◽  
The Impact

This paper aims to present a study linked with the evaluation of the life cycle of both biodegradable and compostable packaging focusing on the impact these have upon the environment, regardless of the life-cycle stage, actually looking at it as a whole. In this article, the evaluation process will focus on the final stage of the product's life - decommissioning and reintegration into the environment. At present, in order for products to be approved by consumers, who are increasingly selective about health and environmental protection, they need to send an appropriate message. The message for consumers can take different forms, being informed about: rational use of resources in the production process, economical and sustainable packaging, attestation of the quality of the product in question, the fact that they are sustainable (compared to similar products in trade). The explosive development of design technologies and software allows the identification of design solutions that lead to the optimization of the project in a new, clean, environmentally friendly formula. Eco-design must ensure technical and aesthetic accuracy, while identifying the optimal shape depending on the chosen material. Consumers are particularly concerned about its persistence in the environment, due to the decomposition time of 100 to 400 years (Zins Beauchesne et al., 2008), its non-renewable fossil resources and the amount of waste allocated to it. The presence of dispersed plastics in nature associated with their persistence in the environment causes major impacts on terrestrial and marine ecosystems (Allsopp et al., 2006). In this context, the objectives of this article are risk assessment, environmental performance assessment, environmental impact assessment and identification of possible changes in each phase of the life cycle of both biodegradable as well as compostable packaging, which in turn may be the originator source of environmental benefits.

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