scholarly journals Modelling the Effects of Pollution on a Population and a Resource in a Polluted Environment

2011 ◽  
Vol 2011 ◽  
pp. 1-31 ◽  
Author(s):  
Victoria Maystruk ◽  
Kenzu Abdella
Keyword(s):  
Removal Rate ◽  
Plant Population ◽  
Pollution Level ◽  
Direct Lyapunov Method ◽  
Animal Population ◽  
Pollution Levels ◽  
Plant Resource ◽  
Mathematical Techniques ◽  
The Stability ◽  
Internal Pollution

A model for the effect of pollution on an animal population partially dependent on a plant resource is examined. Using a system of ordinary differential equations, the model tracks and relates changes in an animal population and its internal pollution levels, a plant population and its internal pollution levels, and the overall environmental pollution level. The model system is analysed using standard mathematical techniques, including the direct Lyapunov method and numerical simulations. Criteria for the stability of the system are found and numerically tested. Three inequalities are sufficient to establish global stability, and a parameter range exists in which these criteria are satisfied. The stability criteria dictate that the system will be globally stable provided that the removal rate of the pollution from the environment, the intrinsic growth rate of the plant population, and the rate the animal population relieves itself of its pollution are all sufficiently large.

scholarly journals Layered Double Hydroxides Precursor as Chloride Inhibitor: Synthesis, Characterization, Assessment of Chloride Adsorption Performance

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2537 ◽  
Author(s):  
Lin Chi ◽  
Zheng Wang ◽  
Youfang Zhou ◽  
Shuang Lu ◽  
Yan Yao
Keyword(s):  
Removal Rate ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ions ◽  
Ion Removal ◽  
Hydraulic Concrete ◽  
Adsorption Behaviors ◽  
The Stability ◽  
Inhibition Performance ◽  
Double Hydroxides

In this study, the chloride adsorption behaviors of CaAl-Cl LDH precursors with various Ca:Al ratios were investigated. The optimal chloride ion removal rate was 87.06% due to the formation of hydrocalumite. The chloride adsorption products of CaAl-Cl LDH precursors were further characterized by X-ray diffraction analysis and atomic structure analysis, the adsorption mechanism was considered to be co-precipitate process. The chloride adsorption behaviors of cementitious materials blended with CaAl-Cl LDH precursors were further investigated. Leaching test according to Test Code for Hydraulic Concrete (SL352-2006) was performed to testify the stability of chloride ions in the mortar. The results show that more than 98.3% chloride ions were immobilized in cement mortar blended with CaAl-Cl LDH precursor and cannot be easily released again. The inhibition performance of steel in the electrolytes with/without CaAl LDH precursor was investigated by using electrochemical measurements. The results indicate that CaAl LDH precursor can effectively protect the passive film on steel surface by chloride adsorption. Considering the high anion exchange capacities of the LDHs, synthesized chloride adsorbent precursor can be applied as new inhibitors blended in cementitious materials to prevent the chloride-induced deterioration. Moreover, the application of chloride adsorption on CaAl-Cl LDH could also be of interest for the application of seawater blended concrete.

Machining Characteristics of EDM for Non-Conductive Ceramics Using Adherent Copper Foils

2010 ◽  
Vol 154-155 ◽  
pp. 794-805 ◽  
Author(s):  
Yao Jang Lin ◽  
Yan Cherng Lin ◽  
A Cheng Wang ◽  
Der An Wang ◽  
Han Ming Chow
Keyword(s):  
Removal Rate ◽  
Pyrolytic Carbon ◽  
Industrial Applications ◽  
Tool Electrode ◽  
Electrode Wear ◽  
Machining Parameters ◽  
Machined Surface ◽  
Conductive Material ◽  
Conductive Ceramics ◽  
The Stability

This study investigates the feasibility of EDM for processing ZrO2 and Al2O3 of non-conductive ceramics, which were covered by an assisted conductive material, an adherent copper foil, on the workpiece surface. The conductive material adhered on the surface of the non-conductive ceramics would induce a series of electrical discharges between the tool electrode and the workpiece in the initial stage of the EDM process. Thus, the pyrolytic carbon that cracked from kerosene was formed and deposited on the machined surface to maintain the progress of EDM. In this work, the essential EDM machining parameters were varied to determine the effects on material removal rate (MRR), electrode wear rate (EWR), and surface roughness. The stability of EDM progress and the surface integrities of ZrO2 and Al2O3 machined by EDM were also investigated. The aim of this study is to explore the feasibility and development of an applicable process for processing non-conductive ceramics through EDM. Moreover, the exploitation of this work can be applied to industrial applications and used to develop machining techniques for non-conductive ceramics.

Achieving Highly Stable Removal Rate in Small Tool Polishing of Glass Lenses

2020 ◽  
Author(s):  
Urara Satake ◽  
Toshiyuki Enomoto ◽  
Teppei Miyagawa ◽  
Takuya Ohsumi
Keyword(s):  
Removal Rate ◽  
Industrial Applications ◽  
Polishing Process ◽  
The Stability ◽  
Sudden Decrease ◽  
Polishing Pads ◽  
Glass Lenses ◽  
Polishing Pressure ◽  
Small Tool

Abstract The demand for improving the image quality of cameras has increased significantly, especially in industrial applications, such as broadcasting, on-vehicle, security, factory automation, and medicine. Surface of glass lenses, which is a key component of cameras, is formed and finished by polishing using small tools. However, the existing small tool polishing technologies exhibit serious problems including an unstable removal rate with the accumulated polishing time. In concrete, low removal rate at the beginning of the polishing process and sudden decrease in the removal rate during the polishing process significantly deteriorate stability of the removal rate. To improve the stability of the removal rate, we proposed a vibration-assisted polishing method using newly developed polishing pads with titanium dioxide particles in the previous work. Polishing experiments on glass lenses confirmed that the variation in the removal rate was suppressed by the developed polishing method; however, the reason for the improvement, in concrete, the relation between the vibration of polishing pressure and the stability of the removal rate remains unknown. In this study, we investigated and clarified the effect of the vibration of polishing pressure on the surface conditions of polishing pads, which strongly affected removal rate.

scholarly journals Bright-Dark and Multi Solitons Solutions of (3 + 1)-Dimensional Cubic-Quintic Complex Ginzburg–Landau Dynamical Equation with Applications and Stability

Entropy ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 202 ◽  
Author(s):  
Chen Yue ◽  
Dianchen Lu ◽  
Muhammad Arshad ◽  
Naila Nasreen ◽  
Xiaoyong Qian
Keyword(s):  
Dynamical Equation ◽  
Landau Equation ◽  
Applied Physics ◽  
Ginzburg Landau ◽  
Open Set ◽  
Trigonometric Function Solutions ◽  
Kink Waves ◽  
Mathematical Techniques ◽  
The Stability ◽  
Complex Phenomena

In this paper, bright-dark, multi solitons, and other solutions of a (3 + 1)-dimensional cubic-quintic complex Ginzburg–Landau (CQCGL) dynamical equation are constructed via employing three proposed mathematical techniques. The propagation of ultrashort optical solitons in optical fiber is modeled by this equation. The complex Ginzburg–Landau equation with broken phase symmetry has strict positive space–time entropy for an open set of parameter values. The exact wave results in the forms of dark-bright solitons, breather-type solitons, multi solitons interaction, kink and anti-kink waves, solitary waves, periodic and trigonometric function solutions are achieved. These exact solutions have key applications in engineering and applied physics. The wave solutions that are constructed from existing techniques and novel structures of solitons can be obtained by giving the special values to parameters involved in these methods. The stability of this model is examined by employing the modulation instability analysis which confirms that the model is stable. The movements of some results are depicted graphically, which are constructive to researchers for understanding the complex phenomena of this model.

scholarly journals PVDF-Modified Nafion Membrane for Improved Performance of MFC

Membranes ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 185 ◽  
Author(s):  
Liping Fan ◽  
Junyi Shi ◽  
Yaobin Xi
Keyword(s):  
Microbial Fuel Cells ◽  
Polyvinylidene Fluoride ◽  
Output Voltage ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Proton Exchange ◽  
Nafion Membrane ◽  
Basic Material ◽  
Molasses Wastewater ◽  
The Stability

Low power production and unstable power supply are important bottlenecks restricting the application of microbial fuel cells (MFCs). It is necessary to explore effective methods to improve MFC performance. By using molasses wastewater as fuel, carbon felt as an electrode, and the mixture of K3[Fe(CN)6] and NaCl as a catholyte, an MFC experimental system was set up to study the performance of MFCs with three different proton exchange membranes. A Nafion membrane was used as the basic material, and polyvinylidene fluoride (PVDF) and acetone-modified PVDF were used to modify it, respectively. The experimental results show that a PVDF-modified membrane can improve the water absorption effectively and, thus, make the MFC have greater power generation and better wastewater treatment effect. The acetone-modified PVDF can further improve the stability of output power of the MFC. When the acetone-modified PVDF was used to modify the Nafion membrane, the steady output voltage of the MFC was above 0.21 V, and the Chemical Oxygen Demand (COD) removal rate for molasses wastewater was about 66.7%, which were 96.3% and 75.1% higher than that of the MFC with the ordinary Nafion membrane. Membrane modification with acetone-modified PVDF can not only increase the output voltage of the MFC but also improve the stability of its output electrical energy.

Stabilization of Removal Rate in Small Tool Polishing of Glass Lenses

2019 ◽  
Vol 13 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Urara Satake ◽  
Toshiyuki Enomoto ◽  
Teppei Miyagawa ◽  
Takuya Ohsumi ◽  
Hidenori Nakagawa ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Material Removal Rate ◽  
Time Variation ◽  
Material Removal ◽  
Removal Rate ◽  
Polishing Process ◽  
Polishing Pad ◽  
The Stability ◽  
Polishing Pads ◽  
Glass Lenses

The demand for improving the image quality of cameras has increased significantly, especially in industrial fields such as broadcasting, on-vehicle, security, factory automation, and medicine. The surface of glass lenses as a key component of cameras is formed and finished by polishing using small tools. The existing polishing technologies, however, exhibit serious problems including an unstable material removal rate over time. In our previous work, the mechanism of time variation in material removal rate was clarified. Based on the findings, a vibration-assisted polishing method using polishing pads containing titanium dioxide particles was developed for improving the stability of the material removal rate with the accumulated polishing time. Our experiments revealed that the proposed polishing method suppressed the time variation significantly in the material removal rate. The developed polishing pads, however, possessed a short life because of their poor wear resistance; as such, they could not be applied to the mass-production process of lenses. In this study, we applied the vibration-assisted polishing method to the polishing process using commercial polishing pads that exhibit sufficient wear resistance for practical use. To investigate the effect of vibration on the stability of the material removal rate, polishing experiments and the observation of slurry flow on the surface of the polishing pads during the vibration-assisted polishing process were conducted. Based on the findings, a new polishing method utilizing a large-amplitude high-frequency vibration applied to the polishing pressure was developed. In addition, a new polishing method utilizing the overhang of a polishing pad, where the polishing pad was moved to hang over the edge of the workpiece for incorporating periodic dressing processes of the polishing pad surface during the polishing process, was also developed. Our polishing experiments revealed that both the proposed polishing methods improved the stability of the material removal rate significantly over the course of the polishing process.

Analysis of Chemical Action of Oxidants in Chemical Mechanical Polishing of SiC Crystal Substrate

2014 ◽  
Vol 1027 ◽  
pp. 213-216
Author(s):  
Su Fang Fu ◽  
Jian Guo Yao ◽  
Li Jie Ma ◽  
Jian Xiu Su
Keyword(s):  
Chemical Mechanical Polishing ◽  
Material Removal ◽  
Removal Rate ◽  
Mechanical Polishing ◽  
Key Factors ◽  
Chemical Action ◽  
Crystal Substrate ◽  
The Stability ◽  
Polishing Efficiency

Chemical mechanical polishing (CMP) had been considered as the most practical and effective method of achieving an ultra-smooth and non-damage surface in manufacturing SiC crystal substrate. CMP slurry was one of the key factors of CMP technology. In this paper, through investigating the changes of several core factors to evaluate the performance of CMP, such as the material removal rate (MRR), surface roughness Ra, 3D surface profiler, etc., the influence of various slurry and its content on the polishing efficiency and surface finish quality had been studied. The research results showed that different oxidant had different chemical action mechanism, also affecting the stability of CMP slurry and surface quality of specimen; adding suitable an oxidant to slurry could effectively improve the CMP performance.

Research of PZT Excited Discharge Channel Compression Micro-EDM Techniques

2013 ◽  
Vol 645 ◽  
pp. 363-366
Author(s):  
Lian Ming Du ◽  
Qin He Zhang ◽  
Jian Hua Zhang ◽  
Ya Zhang
Keyword(s):  
Discharge Channel ◽  
Removal Rate ◽  
New Technology ◽  
Machining Process ◽  
Micro Edm ◽  
System Composition ◽  
The Stability ◽  
Discharge Gap ◽  
Edm Process ◽  
Sync Pulse

In micro-EDM, the debris generated in machining process is difficult to be moved from the discharging gap, the discharge state is instability, and the material removal rate is low. A new method of PZT incentive synchronous compression discharge channel micro-EDM is presented based on the inverse piezoelectric effect of PZT piezoelectric ceramics, using a spark discharge and PZT sync pulse power. In this paper, the system composition and machining principles are described in detail, and its machining mechanism is analyzed in terms of the experiments. By the experiments, it is certificated that on the process of PZT sync compressing discharge channel machining, the state of discharge gap, the machining efficiency and quality can be improved, the throw out of debris makes easier, and then the stability of micro-EDM process is raised, which indicated that this new technology has wide application prospect in the field of micro manufacturing.

Experimental Study on Treatment of Urban Runoff by Embankment Flow System

2014 ◽  
Vol 675-677 ◽  
pp. 534-538
Author(s):  
Peng Fei Wang ◽  
Hai Bo Li ◽  
Ying Hua Li
Keyword(s):  
Tall Fescue ◽  
Flow System ◽  
Removal Rate ◽  
Urban Runoff ◽  
Suspended Solid ◽  
Mixed Matrix ◽  
Purification Efficiency ◽  
Flowing System ◽  
The Stability ◽  
Single Matrix

Test by establishing different embankment flowing systems studied the combination of different substrates and different plants purification efficiency and the effect on the stability of the efficiency of the flowing system. Results show that, the mixed matrix(loess, sand and brown loam) is more efficiency than the single matrix, especially for suspended solid (SS), ammonia (NH3-N), total phosphorus (TP) removal, the removal rate is over 60%. Tall fescue (Festuca elata Keng ex E. Alexeev) is more suitable for the flowing system than perennial ryegrass (Lolium perenne L.). And, long running of the system is possible.

scholarly journals CHARACTERIZATION OF VOLATILE ORGANIC COMPOUNDS AND ODOUR POLLUTION IN ATMOSPHERE AT OIL AND GASOLINE HANDLING AND PROCESSING IMPACT ZONE

2019 ◽  
Vol 1 ◽  
pp. 171
Author(s):  
Evita Muizniece-Treija ◽  
Iveta Šteinberga
Keyword(s):  
Air Quality ◽  
Human Health ◽  
Well Being ◽  
Pollution Level ◽  
Gaseous Pollutants ◽  
Monitoring Site ◽  
Short Term ◽  
Limit Values ◽  
Private Monitoring ◽  
Pollution Levels

Air quality pollution problem is still one of the crucial points for citizens in Europe for already receiving increasing attention, particularly because of the major European cities 10 and more years. Although the EU's long-term goal is to achieve levels of air quality that do not impact and risks to human health and the environment, many of member states still didn`t reach stated goals. Additionally, to gaseous pollutants, recently specific type of pollution, - odour, seems to become more important. Usually in order to determine pollution levels, national, municipal and private monitoring equipment is used. For this research municipal monitoring site in Riga (Latvia), at Milgravja Street 10, controlling gaseous pollutants (SO2, O3, BTX, PM10) and airborne particulate matter, and private monitoring results from Riga, Milgravja Street 16, where odour pollution was obtained, are analysed. Distance between both stations are just 500 m. Measurements at municipal monitoring site is obtained by DOAS and gravimetric sampling, while at Milgravja 16 by photoionization method or so-called “electronic nose”. Monitoring results in municipal station show that in 2017 the average benzene concentration was 4,87 ug/m3, toluene – 8,89 ug /m3 and xylene – 5,07 ug/m3, while the odour pollution level does not exceed 5 odour units. In general estimation of pollution averaged annually do not show and explain variability of pollution levels. It`s well known that high BTX and odour pollution episodes occur in shorter periods, thus short term limit values would be useful in order to characterize short term effects on human health and well-being.

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