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Solid ammonia dosing technology has been extensively researched in the last decade as an effective solution to address issues such as urea crystallization and carrier blockage in traditional selective catalyst reduction (SCR) systems. In this study, a comparison of nitrogen oxide (NOx) conversion efficiency between solid ammonia dosing (SAD) and Adblue dosing on a heavy-duty diesel engine SCR system was conducted. First, an engine emission test bench with SAD SCR and Adblue SCR systems was established. Subsequently, both dosing systems were tested and studied on the engine emission test rig. The results showed that the NOx conversion efficiency of SAD was slightly improved by approximately 2%–5% when the catalyst upstream temperature exceeded 250°C, compared with the Adblue system. This improvement can be attributed to the better mixing ability of SAD. Additionally, SAD demonstrated significant advantages in avoiding issues related to urea decomposition at low exhaust temperatures. Furthermore, similar results were observed in the emission cycle test results of the engine. Under the European steady-state cycle (ESC) and European transient cycle (ETC) conditions, the NOx conversion efficiency of SAD was only slightly higher than that of the Adblue system by about 2%. However, under the world harmonized transient cycle (WHTC) condition, where more low-temperature operating conditions are included, the beneficial weighted NOx conversion efficiency of SAD increased to approximately 7.4% at a release condition of 190°C. [ABSTRACT FROM AUTHOR]

Heavy-duty diesel vehicles are a significant source of nitrogen oxides (NOx) in the atmosphere. The Selective Catalytic Reduction (SCR) system is a primary aftertreatment device for reducing NOx emissions from heavy-duty diesel vehicles. With increasingly stringent NOx emission regulations for heavy-duty vehicles in major countries, there is a growing focus on reducing NOx emissions under low exhaust temperature conditions, as well as monitoring the conversion efficiency of the SCR system over its entire lifecycle. By reviewing relevant literature mainly from the past five years, this paper reviews the development trends and related research results of SCR technology, focusing on two main aspects: low-temperature NOx reduction technology and the combination of SCR systems with remote On-Board Diagnostics (OBD). Regarding low-temperature NOx reduction technology, the results of the review indicate that the combination of multiple catalytic shows potential for achieving high conversion efficiency across a wide temperature range; advanced SCR system arrangement can accelerate the increase in exhaust temperature within the SCR system; solid ammonium and gaseous reductants can effectively address the issue of urea not being able to be injected under low-temperature exhaust conditions. As for the combination of SCR systems with remote OBD, remote OBD can accurately assess NOx emissions from heavy-duty vehicles, but it needs algorithms to correct data and match the emission testing process required by regulations. Remote OBD systems are crucial for detecting SCR tampering, but algorithms must be developed to balance accuracy with computational efficiency. This review provides updated information on the current research status and development directions in SCR technologies, offering valuable insights for future research into advanced SCR systems. [ABSTRACT FROM AUTHOR]

While selective catalytic reduction (SCR) has long been indispensable for nitrogen oxide (NOx) removal, optimizing its performance remains a significant challenge. This study investigates the combined effects of structural and intake parameters on SCR performance, an aspect often overlooked in previous research. This paper innovatively developed a three-dimensional SCR channel model and employed response surface methodology to conduct an in-depth analysis of multiple key factors. This multidimensional, multi-method approach enables a more comprehensive understanding of SCR system mechanics. Through target optimization, we achieved a simultaneous improvement in three critical indicators: the NOx conversion rate, pressure drop, and ammonia slip. It is worth noting that the NOx conversion rate has been optimized from 17.07% to 98.25%, the pressure drop has been increased from 3454.62 Pa to 2558.74 Pa, and the NH3 slip has been transformed from 122.26 ppm to 17.49 ppm. These results not only advance the theoretical understanding of SCR technology but also provide valuable design insights for practical applications. Our findings pave the way for the development of more efficient and environmentally friendly SCR systems, potentially revolutionizing NOx control in various industries. [ABSTRACT FROM AUTHOR]

In order to explore the influence of the temperature of cyclone mixer and urea injection flow rate on NOx conversion efficiency, CFD technology is used to study the SCR catalytic converter for a diesel engine by chemical reaction and steady flow numerical simulation. By changing the temperature of the cyclone mixer and the urea injection flow rate, the concentration and uniformity coefficient of NH3 and the mass fraction of NOx at the outlet are compared under different conditions. The results show that the mass fraction distribution of NOx at the outlet of SCR catalyst presents the law of low center and high edge, and the temperature change of cyclone mixer has little effect on the uniformity coefficient of NH3 velocity. When the temperature is 400 ℃, the NH3 distribution is more uniform, the NH3 generation rate and NOx conversion efficiency are higher. These results indicate that the NOx conversion efficiency and urea utilization rate can be improved by selecting the appropriate urea injection flow rate. [ABSTRACT FROM AUTHOR]

Improving the NOx conversion efficiency and particulate combustion efficiency under cold-start conditions (low-temperature conditions) is still the main challenge faced by catalytic gasoline particulate filter systems (CGPFs). In this study, the physical and mathematical models of novel CGPFs are proposed based on the computational fluid dynamics software. Then, the models are validated based on experiments, and the performances of conventional and novel CGPFs are analyzed comparatively. The comparison conclusions indicate that the NOx conversion efficiency of the novel CGPFs increases by 3.2% and the particulate combustion efficiency increases by 2.7% under the same operating condition. Finally, the effects of exhaust flow vf, exhaust oxygen mass fraction Co, exhaust NO mass fraction CNO, and electric heating power Pe on the NOx conversion efficiency and particulate combustion efficiency are investigated. The weights of each influencing parameter on the NOx conversion efficiency and particulate combustion efficiency are explored by orthogonal tests. The conclusions show that the NOx conversion efficiency is increased by 3.6% and the particulate combustion efficiency is increased by 16.7% compared to the initial condition. This study has an important reference value for improving the purification efficiency of vehicle emission under cold-start conditions. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction (SCR) is applied to a diesel engine for the promising solution of NOX emission. In this study, a diesel engine test bench with an SCR system was developed to clarify the large difference in the NOX emission of diesel engine SCR system under various exhaust conditions. A performance test of the SCR system was also used to determine the single and multi-factor interaction. An SCR model was established using GT-POWER software. A systematic analysis was made to explore the influence of exhaust temperature, exhaust mass flow, and ammonia nitrogen ratio on the SCR performance in the heavy-duty engine. Box-Behnken design and response surface method (RSM) was used to simulate the diesel engine SCR system. An RSM optimization was carried out with the NOX conversion efficiency and NH3 slip rate as optimization objectives, where the exhaust temperature, exhaust mass flow, and ammonia nitrogen ratio were variable factors. The results showed that the NOX conversion efficiency increased by 5% on average every 10 °C in the range of 150-250 °C, while a high level was then observed in the range of 250-450 °C, finally to decline after 450 °C. There was an opposite trend for the influence of exhaust temperature on NH3 slip rate. Specifically, the NH3 slip rate remained at a low level, all within 5% above 250 °C. The NOX conversion efficiency decreased, but the NH3 slip rate increased, with the increase of exhaust mass flow, especially when the exhaust mass flow was above 200 kg / h. When the exhaust mass flow increased by 50 kg / h, the NOX conversion efficiency decreased by 3%, and the NH3 slip rate increased by 4%. The high ammonia nitrogen ratio contributed to improving the NOX conversion efficiency and NH3 slip rate. Particularly, the NOX conversion efficiency maintained a high level, when the ammonia nitrogen ratio was above 0.9. Nevertheless, the NH3 slip rate maintained a low level, when the ammonia nitrogen ratio was below 0.9. It inferred that the appropriate ammonia nitrogen ratio was expected to optimize the SCR performance. In the response surface optimization, a high exhaust temperature and low exhaust mass flow with a suitable ammonia nitrogen ratio can contribute to the NOX conversion efficiency in the high level, while the NH3 slip rate in the low level. An optimal NOX conversion efficiency of SCR performance reached 96.4%, and the NH3 slip rate was only 0.5%, when the exhaust temperature was 350 °C, while the exhaust mass flow rate was 200 kg / h, and the ammonia nitrogen ratio was 1.0. Consequently, an optimal combination of NOX conversion efficiency and NH3 slip rate can be achieved under the optimization of exhaust temperature, exhaust flow and ammonia nitrogen ratio. This finding can provide effective guidance for urea control in an SCR system under different operating conditions of a diesel engine. [ABSTRACT FROM AUTHOR]

A urea injection control strategy for urea-selective catalytic reduction under a transient process is investigated on a heavy-duty diesel engine test bench in this study. The aim is to improve NOx conversion efficiency and reduce ammonia slip. With the selective catalytic reduction system as the research object, an open thermodynamic conservation system is established. The conservation relationship in the process of urea injection, NOx reduction reaction, ammonia storage, and ammonia slip is investigated. The ideal target ammonia storage area and the ammonia storage characteristics during the transient process are studied. The ammonia storage area and boundary, which change with the transient temperature, are established. Correction of real-time ammonia injection is further deduced from the boundary of the area. The world harmonized transient cycle test cycle result showed that compared to feed-forward control, the NOx conversion efficiency increased by 16% and the NH3 slip decreased by 75% when using the proposed real-time ammonia storagemanagement control method. [ABSTRACT FROM AUTHOR]

The Selective Catalytic Reduction on Filter (SCRF) system is yet to be deployed in current heavy-duty diesel engine aftertreatment system. Due to the thermal, space and cost benefits of the SCRF, it could become a useful component of the after-treatment system of a heavy-duty diesel engine, as regulators continue to demand an even cleaner environment. Ammonia cross-sensitivity of NOx sensors at the post-SCRF location poses challenges in measuring NOx emission accurately at this location and in turn affects the NOx conversion efficiency calculations. Developing a model that could replace the NOx sensor helps to mitigate the ammonia cross-sensitivity challenge as well as provides a medium to measure post-SCRF NOx concentration and NOx conversion efficiency while saving the cost on NOx sensors. This work focuses on a data-driven approach to developing a model for predicting NOx conversion efficiency across the SCRF using Artificial Neural Network, Bootstrap Forest, and Boosted Tree methods. Further, the three modeling techniques were also compared for accuracy and computation cost. [Display omitted] • Artificial Neural Network (ANN), Bootstrap forest and Boosted tree modeling approach have been compared. • The possibility of adopting predictive model in place of post SCR/SCRF NOx sensor was evaluated. • It is beneficial to compare models using multiple metrics. • SCRF ammonia cross sensitivity mitigation with predictive model was evaluated. [ABSTRACT FROM AUTHOR]

• Ammonia storage characteristics on a Cu-based zeolite SCR catalyst were investigated experimentally. • The maximum ammonia storage decreases with the increase of exhaust temperature over 220 ℃. • The most extended duration of the ammonia storage process occurred at 220 ℃. • The maximum NOx conversion efficiency attains 80% at 180 ℃ and 100% at 220 ℃ or above. • The ammonia storage and the exhaust temperature are the main factors in NOx conversion performance in SCR catalysts. The ammonia storage characteristics were studied experimentally in two stages before and after shutting off the urea injection on a full-size Cu-based zeolite SCR catalyst. The experiment was conducted under the engine operating conditions with exhaust temperatures of 180, 220, 260, 300, 340, and 380 ℃. The variations of the ammonia storage amount, NOx conversion efficiency, and ammonia slip were separately investigated within the period of ammonia storage and consumption process. The results indicate that the maximum ammonia storage is only 10 g at 180 ℃, but around 43 g at 220 ℃. The maximum ammonia storage decreases with the increase of exhaust temperature over 220 ℃, which drops from 35 g at 260 ℃ down to below 13 g at 380 ℃. The most extended duration of 8082 s on the ammonia storage process occurred at the exhaust temperature of 220 ℃, mainly due to the deposit formation. The time width of the ammonia storage process is shortened with the exhaust temperature increasing over 220 ℃. The maximum NOx conversion efficiency is 80% at the temperature of 180 ℃ and 100% when the temperature rises to 220 ℃ or above. The higher temperature can improve the catalyst activity to supply more activated ammonia reacting with NOx. However, it promotes further ammonia slip. The ammonia storage and exhaust temperature are the main factors in the NOx conversion performance in the SCR catalyst. When the temperature is below 220 ℃, the NOx conversion efficiency strongly depends on the ammonia storage and increases with its amount. With the temperature further rising to 220℃ and above, the impact of the exhaust temperature on NOx conversion efficiency gradually increases. [ABSTRACT FROM AUTHOR]

The working process of high-pressure SCR (HP-SCR) system is a kind of catalytic reaction process in the high-pressure exhaust flow, which involves urea decomposition reaction, catalytic reduction reaction of NOx and oxidizing reaction of NH3. Based on existing exhaust conditions of marine low-speed diesel engines, computational fluid dynamics (CFD) coupled with the chemical reaction kinetics, the catalytic process, and the working performance of the HP-SCR system were correspondingly studied in this paper. With the optimized scheme of the HP-SCR system, concentration uniformity, linear velocity, and total pressure loss were determined. Likewise, the concentration distribution of NH3, NO, and NO2 were obtained, and the catalytic kinetics of the NOx reduction reaction was analyzed. For the optimized scheme, the concentration of NH3 and the flow uniformity of the catalyst upwind section was met with the design requirements of the HP-SCR system, and the pressure loss of the SCR catalyst layer occupied about 40% of the total pressure loss. With NO, NO2, and NH3 existing together in the exhaust, both the standard SCR reaction and fast SCR reaction are competitive, and they mostly react along the first layer of catalyst. Finally, the weighted average value of the NOx emission behind the HP-SCR system was determined using the ISO8717 test cycle E3, and the value was 2.67 g/kWh, which met with the NOx limited requirement of the IMO Tier III. [ABSTRACT FROM AUTHOR]

Increasingly stringent emission regulations call for improvement in the current emissions control technology in heavy-duty diesel engines. In the existing aftertreatment system utilized in diesel engines, there is already a challenge with space and volume, and an attempt to add more components would lead to the consumption of more space and impracticable. The Selective Catalytic Reduction on Filter (SCRF)-an integration of Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) in a single component, offers space saving and favorable thermal inertia opportunities. However, literatures are conflicting on the effect of the SCR and DPF activities on the operations of the SCRF, as both require NO 2 for fast SCR reaction, and passive soot oxidation respectively. This paper presents a detailed experimental characterization of a Silicon-Carbide (Si–C) coated with Copper-Zeolite (Cu-Ze) catalyst SCRF after-treatment component in a heavy-duty diesel engine, evaluated on a laboratory dynamometer. The effect of particulate matter loading on the SCRF activities in steady state, and transient operations was investigated, with emphasis on the simultaneous utilization of NO 2 between the passive soot oxidation activities and SCR reactions-which is a determinant of the NOx conversion efficiency. The SCRF was loaded from 0 g/L up to 5 g/L while passive regeneration and NOx conversion activities were investigated over steady and transient cycles. The investigation has shown that both NOx conversion efficiency and passive soot oxidation increase with particulate matter loading in the SCRF system of a heavy-duty diesel engine. [Display omitted] • Vehicle vocation determines the frequency of active regeneration of SCRF. • With the SCRF, engine can be calibrated for higher engine-out NOx. • Passive regeneration rate in the SCRF increases with loading and occurs below 280° C. • Both NOx conversion efficiency and passive soot oxidation increase with soot loading. [ABSTRACT FROM AUTHOR]

The characteristics of urea injection and NOx conversion efficiency are closely related. A SCR test bench was built based on V2O5-WO3/TiO2 catalyst, and NO, NH3 and O2 feed Streams were dosed by mass flow controllers. The effect of normalized stoichiometric ratio (NSR) and catalyst temperature on ammonia storage, ammonia slip and NOx conversion efficiency was studied. The results show that the influence of NSR and temperature on ammonia storage, ammonia slip and NOx conversion efficiency is obvious. The time of ammonia storage will be shorten with the increase of NSR, then the improving speed of NOx conversion efficiency is high. The NSR fix 2.2, the NOx reduction efficiency increase from 0 to 4.3% within 15 s, and the NOx reduction efficiency increase from 0 to 8.7% within 15 s when NSR set 3.0. The time of ammonia slip and ammonia storage are closely related, the time of ammonia slip will be shorten with the increase of NSR. The method of NSR from larger to the smaller can increase ammonia storage rate and optimize NOx conversion efficiency. Using this injection method to carry out the European transient cycle (ETC) test, the brake specific emission of NOx reduce from 8.26 g/(kW ⋅ h) to 1.91 g/(kW ⋅ h), and the average and peak value of ammonia are 5 X 10-6 and 18 X 10-6, the NOx can reach the National V emission regulations. [ABSTRACT FROM AUTHOR]

• EHC heats up faster and consumes less energy when EHC was coupled behind the DOC. • The adsorption amount of CO, THC and NOx increases with the increase of catalyst loading of PNA. • The NOx average conversion efficiency of the PNA30, PNA50 and PNA70 is 92.65%, 95.27% and 95.72% respectively in the cold start phase. • PNA with catalyst loading of 50 g/ft3 has high adsorption performance. In order to meet the strict emission regulations in the future, passive NOx absorber (PNA) and electrically heated catalyst (EHC) will gradually become the necessary technologies for diesel engines. In this paper, based on a diesel engine with PNA, EHC, diesel oxidation catalyst (DOC), selective catalytic reduction catalyst integrated into diesel particulate filter (SDPF) and selective catalytic reduction catalyst (SCR), the impact of PNA emission characteristics and performance with different catalyst loading were investigated. The results showed that EHC was coupled behind the DOC is more conducive to energy conservation and reducing NOx emissions. Compared with EHC was coupled in front of the DOC, the time for SDPF inlet temperature to reach 180 ℃ was reduced by 123 s, the power consumption of EHC was reduced by 0.25 kWh and nitrogen oxide (NOx) conversion efficiency increased by 16.61% in the cold start phase when EHC was coupled behind the DOC. Meanwhile, PNA has a certain adsorption effect on CO, THC, and NOx. When EHC was coupled behind the DOC, the adsorption amount of carbon monoxide (CO), total hydrocarbon (THC), and NOx increases with the increase of PNA catalyst loading. The maximum adsorption time of PNA for NOx reached 171 s. Similarly, the conversion efficiency of CO, THC, and NOx during the cold start stage also increases with the increase of PNA catalyst loading. The maximum average conversion efficiency of CO, THC, and NOx was 60.58%, 88.60%, and 95.72%, respectively. In cold start phase, the PNA50 has achieved high PNA performance, and the gain brought by higher catalyst loading is not obvious. In medium–high temperature phase, due to the high exhaust temperature, PNA has no effect on the conversion efficiency of CO, THC, and NOx. PN conversion efficiency is more than 99% and is not affected by the PNA type. The findings provide the fundamental insights to promote the application of PNA and EHC in diesel engines and reduce emissions of diesel engines under cold start conditions. [ABSTRACT FROM AUTHOR]

• The number of active sites of the catalyst and the SDPF pressure drop together determine the NOx conversion efficiency. • With increase in catalyst washcoat loading, NOx conversion efficiency first increased and then decreased. • The SDPF could significantly reduce the nucleation-mode particles. • When the catalyst washcoat loading was 90 g/L, the SDPF could obtain the highest NOx conversion efficiency, higher particle filtration efficiency, and low pressure drop. To improve the NOx conversion efficiency (CE) and inlet temperature of selective catalytic reduction (SCR) under low-temperature conditions, SCR coated on diesel particulate filter, so called SDPF, is one of the important technologies to meet the future Euro Ⅶ ultra-low emission regulations for diesel engines. In this study, the effects of different Cu-SSZ-13 catalyst washcoat loadings (60, 90, and 120 g/L) on the SDPF performance were investigated. The results showed that as the catalyst washcoat loading increased, the inlet temperature and pressure drop of the SDPF rose, the high-NOx-conversion-efficiency area expanded toward the low-speed and low-load directions of the engine, and the NOx CE first increased and then decreased. The number of active sites of the catalyst and the SDPF pressure drop together determine the NOx CE. When the catalyst washcoat loading was increased, the nucleation-mode (NM) particle factor decreased significantly, while the accumulation-mode (AM) particle factor decreased slightly. The filtration efficiency of the three types of particles was NM > total > AM from high to low. The higher the washcoat loading, the higher the particle filtration efficiency and the larger the geometric mean diameter. The reduction of NM particles was the result of a combination of the chemical reaction and the physical collection mechanism. [ABSTRACT FROM AUTHOR]

Selective catalytic reduction catalyst coated on filter (SDPF) is one of the important technical routes to meet the future Euro-Ⅶ emission regulations for engines. To efficiently control and optimize the SDPF, it is necessary to have a comprehensive understanding of its regeneration characteristics. Therefore, the temperature, particulate emission characteristics and reduction emission performance of SDPF under the drop to idle (DTI) regeneration with different soot loads were investigated. The results show that, during DTI regeneration, the SDPF inlet outer-ring temperature was the highest and the outlet outer-ring temperature was the lowest, the radial temperature gradient of the outer-ring was larger than that of the inner-ring, and the axial temperature gradient of the rear section was larger than that of the front section. As the soot load increased, the start of regeneration was delayed, the regeneration duration extended, and both the peak temperature and the maximum temperature gradient of the substrate increased. A rapid increase in the proportion of nucleation-mode particle at the SDPF outlet was a signal of the end of DTI regeneration. The higher the soot load, the higher the regeneration efficiency and the lower the particle filtration efficiency and NOx conversion efficiency of the SDPF after DTI regeneration. • The higher the soot load, the longer the DTI regeneration duration. • DTI regeneration was divided into three stages. • High proportion of NM particle (>70%) was a signal of the end of DTI regeneration. • Reduction emission performance of SDPF would decease after DTI regeneration. [ABSTRACT FROM AUTHOR]

The objective of the study is to present the modeling and multi-objective optimization of NOx conversion efficiency and NH3 slip in the Selective Catalytic Reduction (SCR) catalytic converter for a diesel engine. A novel ensemble method based on a support vector machine (SVM) and genetic algorithm (GA) is proposed to establish the models for the prediction of upstream and downstream NOx emissions and NH3 slip. The data for modeling were collected from a steady-state diesel engine bench calibration test. After obtaining the two conflicting objective functions concerned in this study, the non-dominated sorting genetic algorithm (NSGA-II) was implemented to solve the multi-objective optimization problem of maximizing NOx conversion efficiency while minimizing NH3 slip under certain operating points. The optimized SVM models showed great accuracy for the estimation of actual outputs with the Root Mean Squared Error (RMSE) of upstream and downstream NOx emissions and NH3 slip being 44.01 × 10-6, 21.87 × 10-6 and 2.22 × 10-6, respectively. The multi-objective optimization and subsequent decisions for optimal performance have also been presented. [ABSTRACT FROM AUTHOR]

A systematic modeling approach was scrutinized to develop a kinetic model and a novel monolith channel geometry was designed for NH3 selective catalytic reduction (NH3-SCR) over Cu-ZSM-5. The redox characteristic of Cu-based catalysts and the variations of NH3, NOx concentration, and NOx conversion along the axis in porous media channels were studied. The relative pressure drop in different channels, the variations of NH3 and NOx conversion efficiency were analyzed. The model mainly considers NH3 adsorption and desorption, NH3 oxidation, NO oxidation, and NOx reduction. The results showed that the model could accurately predict the NH3-SCR reaction. In addition, it was found that the Cu-based zeolite catalyst had poor low-temperature catalytic performance and good high-temperature activity. Moreover, the catalytic reaction of NH3-SCR was mainly concentrated in the upper part of the reactor. In addition, the hexagonal channel could effectively improve the diffusion rate of gas reactants to the catalyst wall, reduce the pressure drop and improve the catalytic conversion efficiencies of NH3 and NOx. [ABSTRACT FROM AUTHOR]

For the National VI heavy-duty diesel vehicles, NOx emission regulations are becoming more and more stringent, and the selective catalytic reduction (SCR) system has become a necessary device. The design of the adblue nozzle in the SCR system is especially critical, directly affecting the NOx conversion efficiency and deposit formation. According to the structure of a National VI diesel engine exhaust pipe and SCR system, the nozzle is optimized by computational fluid dynamics (CFD) method to avoid the collision between the urea droplets and the exhaust pipe wall, to ensure that the exhaust gas and the urea droplets are as much as possible in full contact to ensure a sufficient urea pyrolysis. With the optimized nozzle, the NH3 distribution uniformity of the inlet face of the SCR catalyst can increase from 0.58 to 0.92. Additionally, test verifications are implemented based on the spray particle size test and the engine bench tests; the results show that the Sauter mean diameter of the optimized nozzle is more decreased than the initial nozzle and that the NOx conversion efficiency of the World Harmonized Transient Cycle (WHTC) and World Harmonized Stationary Cycle (WHSC) cycle improves by nearly 3%; additionally, it can also avoid deposit formation. [ABSTRACT FROM AUTHOR]