Corrosion Hazard Research Articles

Preparation of lignin-based porous carbon through thermochemical activation and nitrogen doping for CO2 selective adsorption

Preparing CO2 adsorbents from biomass feedstock has garnered considerable attention due to its potential for fostering sustainable, economic, and eco-friendly development. Introduction of nitrogen-containing functional groups can enhance the affinity for CO2 of biochar but also inevitably affect the pore structure. The challenge lies in ascertaining and regulating the effect of N-doping on the pore structure. In this work, lignin was activated using KOH, and then followed by urea N-doping through pyrolysis or hydrothermal methods. At small dosages of KOH (the mass ratio of KOH/lignin = 0.25), in addition to introducing nitrogen-containing functional groups, urea modification boosted pore volume of <1 nm favorable for CO2 adsorption through etching carbon skeleton, while the small dosage of KOH reduced its inherent corrosive hazards. Correlation analysis showed that the dominant influencing factor for CO2 adsorption at ambient temperature and pressure was the pore volume with pore size of 0.6–0.8 nm, whereas nitrogen content (especially N-5 content) was the main influencing factor at high temperatures (50 °C) and low pressures (0.15 bar). The peak enhancement of the C–N bond under the CO2 adsorption at 50 °C by in situ diffuse reflectance infrared Fourier transform test indicated that the nitrogen-containing functional groups have a chemisorption effect on CO2. The adsorbent PK-0.25-HU exhibited adsorption capacity of 4.46 mmol/g (25 °C, 1 bar), 2.97 mmol/g (50 °C, 1 bar). Dynamic separation coefficient of CO2/N2 reached 93.82 in a gas mixture of CO2/N2 = 15 %/85 %.

Fabrication of diisocyanate microcapsules for self-healing anti-corrosion coatings via integrating electrospraying and interfacial polymerization

Epoxy resins serve as useful material in anti-corrosion coatings. However, the development of microcracks during the processing or service life of a coating is an inevitable occurrence that markedly degrades its performance and shortens its lifespan. The incorporation of self-healing materials can prolong the coatings' lifespan and enhance the reliability of corrosion prevention processes. In this study, a microencapsulation method via integrating electrospraying and interfacial polymerization (ES-IP) was adopted to synthesize the microcapsules containing 4,4’-bis-methylene cyclohexane diisocyanate (HMDI) successfully. The self-healing capability of these microcapsules within the anti-corrosion coating was successfully validated. The prepared HMDI microcapsules (HMDI-MCs) demonstrate excellent dispersibility, tunable characteristics, and a high core material content of 93 wt%. Self-healing anti-corrosion coatings containing HMDI-MCs were prepared and underwent accelerated corrosion testing in sodium chloride (NaCl) solution. The result showed that HMDI is capable of leaking from microcapsules and undergoing solidification, thus forming a barrier to metal steel from corrosion hazards by endowing the coatings with effective self-healing abilities. This paper expands the application of the ES-IP technique in microencapsulation and suggests that HMDI-MCs have significant potential in self-healing anti-corrosion coating.

Electrodeposited ZIF-67 reinforced polypyrrole coating on ferritic stainless steel substrate with durable anticorrosion performance

The harsh acidic environment containing chloride ions has created serious corrosion hazards for ferritic stainless steels. Zeolitic imidazole frameworks (ZIFs) are a promising material for corrosion protection due to their microstructural and physicochemical properties. In this study, we proposed the electrodeposited ZIF-67 reinforced polypyrrole (PPY) coating (PPY/ZIF-67) for corrosion protection of 430 ferritic stainless steel (430SS). The morphology, microstructure, and anticorrosion behavior of the pristine PPY and hybrid PPY/ZIF-67 coating systems were characterized. The successful electrodeposition of ZIF-67 nanoparticles on the surface of the PPY layer resulted in a uniform distribution and a compact coating structure, which contributed to the overall uniformity of the coating and enhanced both the barrier and activity inhibition functions of the coating. The protective performance of PPY/ZIF-67 coatings was evaluated through electrochemical tests, the results indicated that the anticorrosion efficiency of PPY/ZIF-67 coating (with 0.4 mol/L pyrrole monomer content) reached to 99 %, and the coating demonstrated a durable corrosion protection ability (744 h) in 0.1 mol/L HCl solution. Such performance of can be attributed to the combined effect of the anodic protection provided by the inner PPY film, the active corrosion inhibiting properties of the ZIF-67 nanoparticle layer, and the hindrance of aggressive species by the compact coating structure over the prolonged service time.

Cell membrane-inspired self-assembly corrosion resistant liquid metal composite coating with photothermal/electrothermal anti-icing/de-icing performance

Liquid metals have been expected to be promising photothermal/electrothermal anti-icing materials for their excellent electrical and thermal conductivity. However, inescapable oxidation and corrosion limit the life and efficiency of liquid metal materials. Inspired by the self-assembly of phospholipid molecules in cell membranes, self-assembly corrosion resistant liquid metal composite coating is designed to protect liquid metal from icing and corrosion hazards. Based on self-assembly of fluor‑silicon molecules mimicking phospholipid molecules and micro-nano surface morphology, the coating has water contact angle of 150.8°and icing delay time of 497 s, which is 4.21 times that of unmodified liquid metal. Under the combined action of 80.5 °C photothermal effect and superhydrophobicity, the de-icing efficiency of the coating is 2.04 times that of the unmodified liquid metal. The photothermal de-icing efficiency remains 99.3 % after two months of acid corrosion and 94.4 % after two months of alkali corrosion. In addition, the thermal network of the coating leads to thermal conductivity of 3.66 W/mK and flame retardancy with UL94 at V0 rating. The coating is made into an electrothermal device with 52.5 °C heating temperature and rapidly de-icing property. The cell membrane-inspired self-assembly liquid metal composite coating provides a secure solution for long-term photothermal/electrothermal anti-icing/de-icing in exposed environment.

Corrosion Risk for Process Safety in the Chemical Industry

The aim of this work is to analyze how corrosion risk management influences process safety. Both issues occupy an important niche in the chemical industry. Corrosion risk management includes identifying, analyzing, assessing, and managing corrosion hazards. Process safety is a discipline that focuses on preventing fires, explosions, and accidental releases at chemical process facilities. Corrosion can cause all these detrimental events. &#x0D; There is much literature about both topics, corrosion risk, and process safety, separately, but there are nearly no research works concerning intersection and influence.&#x0D; The level of corrosion failure and its consequences, defining corrosion risk, may be different: the leak of crude oil, natural gas, water, liquid and gaseous hazardous chemicals, fire, explosion, damages, deterioration of the environment, injuries, and death of people and animals. Due to the biological and psychological properties of human nature, we are unlikely to exclude human mistakes.&#x0D; We should pay significant attention to education, dissemination of information, knowledge transfer, collaboration, and communication. Correct corrosion risk management gives rise to the improvement of process safety at stages of design, fabrication, implementation, erection, service, and maintenance of equipment and constructions in the chemical industry.&#x0D; For this realization, specific corrosion mitigation strategies and technologies are described. They are successfully implemented in the chemical industry. It shows how corrosion management and process safety management can be better integrated into practice.&#x0D; The future consideration of the prognosis of corrosion risk with process safety is connected with corrosion modeling. Limitations and challenges of such a forecast are discussed too.&#x0D; Special educational and training programs are developed to help engineers, scientists, professionals, students, and managers learn about corrosion science and engineering

Probabilistic corrosion hazard maps for reinforced concrete infrastructure in coastal regions

The development of probabilistic corrosion hazard maps for reinforced concrete infrastructure exposed to airborne chlorides in coastal regions is addressed in the present work, with special attention to bridges. The methodology developed in this study consists of three steps. Initially, spatial distribution, construction year, and main features of the existing infrastructure are examined together with the general characteristics of the study area. The second step deals with the elaboration of relevant environmental data, including the direction and height of sea waves, sea salinity, temperature, relative humidity, rainfall, speed and direction of wind, and chloride deposition rates. Corrosion hazard maps are obtained next, wherein the corrosion current density is selected as an intensity measure. Particularly, they are elaborated for an assigned probability of exceedance given the exposure time window and concrete mixture. The presented methodology is applied to develop probabilistic corrosion hazard maps for reinforced concrete bridges exposed to the marine atmosphere at Oahu Island (Hawaii, United States). For this case-study, it is also discussed the correlation between the actual condition rating of the existing concrete bridges and the estimated corrosion hazard levels.

Effect of barium ion on the stability and chloride ion binding of ettringite

To lower the corrosion hazards of the steel bar in reinforced concrete, binding chloride ion by producing Cl-AFm is an effective way. In the presence of calcium ions and sulfate ions, Cl-AFm could transform into ettringite, and release the chloride ions into pore solution, with negative effect on reinforced concrete. In order to avoid the negative effect, barium ion was introduced to preferentially precipitate the sulfate ions. In this study, the effect of barium ion on the transformation reaction of ettringite into Cl-AFm was studied, and the combination effect of barium ion and sulfate ion on chloride binding was discussed. The results showed that barium ion could improve the chloride binding capacity of ettringite. The mechanism was that barium ion could be precipitated by sulfate from AFt to form BaSO4, and then result in the formation of Cl-AFm.

Development of corrosion hazard maps for reinforced concrete bridges

AbstractInfrastructures in coastal areas are often prone to several hazards, and thus the elaboration of effective risk management plans in such zones are possible if all relevant threats are considered and analyzed. In this context, the assessment of the corrosion hazard attributable to airborne chlorides is of utmost importance since the resulting deterioration phenomena can heavily jeopardize both reliability and resilience of the infrastructures. Therefore, this contribution aims at proposing the preliminary version of a possible framework for the elaboration of corrosion hazard maps at regional scale for coastal areas, with focus on reinforced concrete bridges. The proposed approach encompasses three main steps. First, the relevant stock of infrastructures vulnerable to chloride‐induced corrosion is identified and quantified. This requires the collection of relevant features, such as construction type, position, and age. Environmental conditions are examined next, including data about sea waves and salinity, wind, temperature, humidity, rainfall, and chloride deposition rate. Finally, the corrosion hazard is estimated in probabilistic sense. The proposed methodology is presented together with the preliminary results obtained from a relevant case study.

Numerical simulation of oil and gas pipeline corrosion based on single- or coupled-factor modeling: A critical review

Numerical simulation is an effective research approach to assess the condition and predict the remaining service life of process pipelines suffering corrosion hazards. This work comprises a critical review of 182 academic articles to analyze environmental factors affecting the pipeline corrosion process, basic numerical methods for corrosion simulation, and single- and coupled-factor numerical investigations. Numerical simulation of corroded pipelines could combine the electrochemical corrosion processes and structural characteristics of pipelines to obtain more accurate results. Multiphysics-based techniques have been successfully applied to simulate the evolution process of corroded pipelines affected by two or more coupled factors under stray current interference. Through integration with learning-based algorithms, predictive studies are conducted to assess the development of corrosion. The challenge for current research is that the remaining types of corrosion are difficult to describe by numerical methods. Opportunities are proposed to improve the pipeline corrosion simulation model to describe more corrosion types and realistic corrosion morphologies, including time-varying corrosion simulation, random field in the simulation, and microelectrochemical corrosion simulation.

Corrosion Hazards in Urban Infrastructure Structures Using the Example of the Al Bayt Stadium in Katar

A significant aspect of corrosion failures and catastrophes originate from trivial mistakes in either the choice or connection of different materials, as well as from inaccurate evaluation of the compatibility between materials and the environment. The example shown in the present paper summarizes several wrong solutions due to a lack of knowledge of the basic rules of corrosion control. By chance, the consequences of these errors already appeared during construction; therefore, they were not able to cause damage during operation. This paper is the third in a series devoted to enhancing the need for professional corrosion control design for infrastructures.

Some Practical Hints on Preservation of Aircraft Engines Using a Rig from Corrosion Problems

Aircrafts need to be grounded for want of routine scheduled maintenance and inspection after certain period of flying hours. During such maintenance practices, the turbo-propeller engines are kept dismantled, un- installed and non-operative conditions for a longer period even up to two years. During this non-operative period, the engines and components are susceptible to extensive chronic corrosion hazards. To prevent this hazard, the engines and components are required to be preserved both internally and externally from corrosion that is the engine components such as turbine, turbine blades, compressor, fuel nozzles, fuel system pipelines, diffuser, combustion cum mixing chamber, expansion nozzle and exhaust manifold. Over the long experience of operating the aircrafts, it has been observed that the appliance provided by the manufacturer is only meant for internal corrosion preservation purposes of the operative and installed engines and cannot be used for external corrosion preservation of non-operative and un installed engines which led to drastic reduction of engine lives and unsafe operating conditions to the aircrafts due to inherent materialistic corrosive effects. The material of the turbine blades could not able to withstand its designed high combustion temperature due to the corrosion problems, which leads to unsafe engine conditions. The problem was attributable to the design factor that the high pressure cock in the fuel supply system could open and allow the preservative oil to enter into the main fuel system only when sufficient oil pressure is built up in associative oil system, which needs rotating the engines at least in idling speeds. Simulating this mandatory condition is not possible for the non-operative uninstalled engines. To overcome the corrosion hazard problem of aircraft engines, a bogie hinge joint flushing device has been designed, fabricated and tested using the local resources after taking into consideration of this important engine external preservation requirements, layout of the turbo-propeller engine power plant and fuel supply systems. This innovative external preservation rig has got multiple options coupled with internal preservation for preserving the engine components such as turbine, turbine blades, compressor, fuel nozzles, fuel system pipelines, diffuser, combustion cum mixing chamber, expansion nozzle and exhaust manifold during the course of long maintenance period. The newly designed and developed external preservation rig has resulted in achieving the complete external preservation requirements of following categories of turbo-propeller engines. a) New/overhauled engines in storage and kept on expiry of preservation life b)Installed engine required to be removed for storage but cannot be cranked or rotated c) Installed engines that are not in running condition/installation-seized engines d) Uninstalled engine for defect investigations/defect rectifications e) Non operative unsafe engines

Численная идентификация показателей коррозии при оценке технического состояния оборудования

The method is presented in the article concerning numerical identification of corrosion and corrosion resistance of metals, which serves to determine the degree of hazard of the corrosive state of technical devices of hazardous production facilities. Currently, the causes of metal failure are determined by metallography, radiography, ultrasonic, color, magnetic particle inspection or sample testing. Risk of the development of corrosion processes, depending on the type of corrosion, the characteristics of its shape, the depth of corrosion damage and the area of the affected surfaces, is determined visually or by the instrumental detection methods. Numerical identification of the indicators of corrosion and corrosion resistance of metals, proposed in the work, is carried out taking into account the location of the corrosion process, the form of corrosion damage, the size, unevenness and depth of penetration of various types of corrosion, the degree of damage to the surface by uniform and local corrosion (spots, ulcers, pitting). At the same time, according to the initial size of surface and deep corrosion, the actual size of the corrosion wear of a structural element is determined, and according to the scheme of a typical type and characteristic of the form of corrosion damage, the type of corrosion is determined. Further, taking into account the corrosion hazard score in accordance with the scale of corrosion resistance, a numerical indicator of corrosion and corrosion resistance of the structural metal is determined. Studies showed that the numerical identification of the indicators of corrosion and corrosion resistance of metals makes it possible to match the type of corrosion and the characteristics of the form of corrosion damage with the corrosion coefficient depending on the scheme of a typical type of corrosion damage. In addition, numerical identification shows the extent of damage to the surface by uniform and localized corrosion, including spots, pitting and other types of corrosion. Thus, it is applicable to determine the degree of corrosion hazard in assessing the technical condition and establishing the service life at any stage of the life cycle of equipment in hazardous industries.

ОЦІНКА КОРОЗІЙНОЇ ЗАХИЩЕНОСТІ КОНСТРУКЦІЙ ТА СПОРУД ЗА ФАКТИЧНИМ СТАНОМ

Expansion of functional possibilities of the use of combined designs in the construction, improvement of architectural expressiveness of buildings and structures determine the need for improved requirements to ensure the quality and reliability of means and methods of corrosion protection. Currently, the development of computational methods to assess the reliability and structural safety associated with the construction of in-formation-analytical database key parameters of corrosion condition of metal construction. Methodology. This way creates the basis for setting and implementing management tasks operational life of buildings and structures in corrosive environments by improving the quality and reliability of primary and secondary protection of steel structures based on the level of corrosion hazard. Results. When using the principles of the process approach is the formulation and implementation of tasks of management of operational service life in corrosive environments. The principles of ensuring safety in terms of corrosion risk include the rationale for the sequence of steps to evaluate the survivability of building structures based on the principles of robust design, improvement and control measures the primary and secondary corrosion protection. Scientific novelty. The implementation of protection measures against corrosion according to the corrosion risk criterion helps to ensure the requirements of reliability of building structures in accordance with the design provisions of limit state method and to solve the problems of control of technological security for the rated life of construction projects. objects. Practical significance. The proposed generalized indicators of the actual structures’ corrosion state determine the structure’s operability as a whole. The functional dependencies between the operability of the main and auxiliary structures are established. The relationship between the values of corrosion resistance indicators and metal structures durability are determined. Actual technical condition control consists of checking that the values of these indicators are within acceptable limits. Taking into account the degree of operating environment aggressiveness is one of the determining factors in order to ensure the secondary protection effectiveness against corrosion. This procedure is the basis for the rational specifications appointment for anti-corrosion protection systems with subsequent display in the design and technological documentation

Combined Biological Method for Simultaneous Removal of Hydrogen Sulphide and Volatile Methylsiloxanes from Biogas

Hydrogen sulphide (H2S) and volatile methylsiloxanes (VMSs) are key pollutants from the point of view of the operators of biogas plants. H2S poses corrosive hazards, while VMSs transform into difficult-to-remove deposits, reducing the availability and yield of biogas combustion equipment. This study provides a critical overview and evaluation (so-called SWOT analysis) of implemented and promising methods to reduce the content of the above pollutants in biogas, with particular emphasis on biological techniques. The aim of the analyses was to develop an innovative concept for a hybrid biological method for the combined removal of H2S and VMSs using the same device, i.e., a two-phase biotrickling filter (BTF), in which the organic phase that intensifies the mass transfer of VMSs is in the form of a low-viscosity methyl silicone oil. The finally developed technological schematic diagram includes the basic devices and media streams. The concept is characterized by closed media circuits and comprehensively solves the problem of purifying biogas from sewage sludge. In conclusion, key issues requiring further research are identified.

Numerical study on the effects of primary air ratio on ultra-low-load combustion characteristics of a 1050 MW coal-fired boiler considering high-temperature corrosion

Primary air significantly impacts the ultra-low-load combustion of coal-fired utility boilers. In this study, eleven combustion scenarios with varied primary air ratios (the flowrate ratio of primary air to the total air, PAR) were numerically investigated for a 1050 MW double-tangential circular coal-fired boiler under ultra-low load. The effects of PAR on temperature distribution, coal burnout, and gas species were thoroughly examined. Meanwhile, special attention was paid to the reducing atmosphere near furnace walls for alleviating the problem of high-temperature corrosion. Results show that a relatively large high-temperature region in the furnace is achieved at PAR = 0.153, contributing to combustion stability under ultra-low load conditions. Although the residence time tends to be shortened as PAR increases from 0.123 to 0.275, the amount of unburned carbon in coal particles has a general trend of decreasing because of more available oxygen from primary air. Due to the high excess air coefficient at ultra-low load, strong reducing atmosphere and high-temperature regions mostly concentrate around the operating coal burners, posing corrosion hazard there. As PAR increases to 0.275, the area of high CO concentration regions near furnace walls and the maximum CO concentration decrease noticeably, indicating less pronounced high-temperature corrosion at large values of PAR. NO emissions increase from 294.4 mg/Nm3 to 823.7 mg/Nm3 with increasing PAR from 0.123 to 0.275. This is shown to be related to the weakened reducing atmosphere as well as the reduced residence time of the coal particles as PAR increases.

Risk analysis of the sodium hypochlorite production process: Focus on the chlorine line

Mainly in the first part of COVID-19 pandemics, sodium hypochlorite was used as disinfectant, surprisingly also to spray over people. Several hazards may be associated to the production of this compound, such as chlorine gas toxicity and explosive hazards, due to the presence of hydrogen and chlorine, and corrosive hazards. Thus, loss prevention strategies must be ad-hoc developed to mitigate the risks. In the present work, the risk assessment of the first block of the process was performed, focusing the attention on chlorine risks. To this end, HAZOP analysis was first performed to identify the most critical top event, noticing the major issues in the quality of the final product and in the release of chlorine from pipes. Then, the fault tree analysis was built to calculate its failure rate. CFD simulations were used instead of empirical model to assess with a rigorous approach the chlorine dispersion, taking into account all the boundary conditions. In particular, by setting a hazardous chlorine concentration of 180 ppm corresponding to 50% fatalities for chlorine exposition for an exposure of 60 min, results without aspiration demonstrate the possibility for the cloud to impact workers at ground level also very far from the source point, while the chlorine cloud is moved upwards with a maximum length of 6.5 m when an aspiration is used, although the air ventilation speed is kept low.

Risk analysis on corrosion of submarine oil and gas pipelines based on hybrid Bayesian network

Submarine pipeline is currently the safest and most economical transportation of subsea oil and gas. Corrosion is one of the main threats to submarine pipelines because of the corrosive of the sea. Therefore, it is significative to evaluate the corrosion risk of the submarine pipelines. In this work, a fault tree model is first employed to identify the corrosion hazards in the transportation process. To overcome the limitations of the fault tree analysis for the states of the events, a Bayesian network (BN) is established through mapping from the fault tree model. Because of the limitations of objective data, experts’ judgment combining fuzzy set theory are used to determine the parameters in the BN. The dynamic nodes in the BN are divided into real-time and discrete nodes, and the dynamic characteristics of them are displayed by the evidence nodes. In this way, when a new observation occurs, the real-time risk analysis of the corroded submarine pipeline is realized. Finally, a case study is carried out to verify the risk level variation with the observing events at different moments. Results shows that the proposed model can dynamically characterize the corrosion risk of the submarine pipeline and provide suggestions for the risk reduction.

THE EFFECT OF TIME VARIATION ON CORROSION BEHAVIOUR OF ASTM A36 IN SEAWATER FROM WEST BANGKA OF BANGKA BELITUNG ISLANDS, INDONESIA

Corrosion hazards in marine environmental construction have been studied. ASTM A36 can be widely used in various industrial sectors and oil extracted offshore. The main objective of this study is to analyze the influence of variation immersion time to corrosion behaviour ASTM A36 by using seawater from Bangka Barat Regency, Bangka Belitung Islands as a corrosive media by performing Brinell hardness test, measurement of weight loss and corrosion rate, and and confirm the data obtained with the formed of microstructure. The results revealed that immersion time of 144 hours produced the highest corrosion rate of 27.97 Mpy and but has the lowest hardness number 136,924 BHN. Microstructural observations found the presence of brownish yellow and black (magnetic Fe3O4) corrosion patterns increased along with the increasing immersion time due to the lack of oxygen concentration during the specimen corrosion process.

Corrosion risk assessment of the oil flow line in Southern Iraq

The risk assessment for three pipelines belonging to the Basra Oil Company (X1, X2, X3), to develop an appropriate risk mitigation plan for each pipeline to address all high risks. Corrosion risks were assessed using a 5 * 5 matrix. Now, the risk assessment for X1 showed that the POF for internal corrosion is 5, which means that its risk is high due to salinity and the presence of CO, H2S and POF for external corrosion is 1 less than the corrosion, while for Flowline X2 the probability of internal corrosion is 4 and external is 4 because there is no Cathodic protection applied due to CO2, H2S and Flowline X3 have 8 leaks due to internal corrosion so the hazard rating was very high 5 and could be due to salinity, CO2, fluid flow rate and water cuts. External corrosion hazard rating 4 is considered high because there is no coating, no cathodic protection is applied.

Solid Acid Hydrolysis for Isolation of Cellulose Nanocrystals and Chitin Nanocrystals – A mini review

Cellulose and chitin are two of the most abundant biopolymer on earth, have been attracted a lot of interest from many researchers, especially related to their nanoparticles form. Recently the method to extract them into nanoscale materials mostly by mineral or liquid acid hydrolysis, such as sulfuric and hydrochloric acid. Despite their high yield production, many disadvantages are produced by their use as a hydrolysis catalyst, such as low thermal stability and are difficult to be functionalized due to the presence of sulfate groups, tendency to be aggregated due to the bare surface charge density, the potential excessive degradation of cellulose; and large amounts of effluent will be produced due to the neutralization stage and corrosion hazards to the equipment and environment. To overcome the drawback of those acids, solid acid can be used to produce cellulose (CNC) and chitin nanocrystals (ChNC). Their ability to recrystallize and recycle makes them more environmentally friendly, furthermore, most of the acid can do esterification on the surface of cellulose and chitin. The purpose of this paper is to provide a critical review of recent progress related to solid acid hydrolysis since they have interesting characterization even some of their attribute is better than the conventional method.