In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particul...In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particularly pronounced with an increase in ridge width,resulting in multimode problems.To tackle this,an innovative multi ridge waveguide structure based on the principle of supersymmetry(SUSY)was proposed.This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side.The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design,and the optical loss of the auxiliary waveguides suppresses these modes,thereby achieving fundamental mode lasing of the wider main waveguide.This paper employs the finite difference eigenmode(FDE)method to perform detailed structural modeling and simulation optimization of the 4.6μm wavelength quantum cascade laser,successfully achieving a single transverse mode QCL with a ridge width of 10μm.In comparison to the traditional single-mode QCL(with a ridge width of about 5μm),the MRW structure has the potential to increase the gain area of the laser by 100%.This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers,which is of considerable significance.展开更多
Micro Aerial Vehicles(MAVs) are the smallest artificial aircraft.Most of the flapping wings MAVs are powered by electric motors of various capacities.We report in this paper the application of piezoelectric actuators ...Micro Aerial Vehicles(MAVs) are the smallest artificial aircraft.Most of the flapping wings MAVs are powered by electric motors of various capacities.We report in this paper the application of piezoelectric actuators as power system for a flapping wing MAV using a compliant displacement amplification mechanism.The actuator used for this application is a pre-stressed cut piece of TH-7R type Thunder actuator.A two-bar compliant mechanism with two flexures has been developed to convert the linear displacement into angular movement and amplification.The specimens were made from carbon fiber links and nylon flexures.We also proposed to use the product of frequency(F) and tip displacement(D), F * D as a criteria for the characterization of an amplifying mechanism.The best specimen according to this criterion is obtained for a 5mm length flexure specimen made of three layers of nylon.The F*D value obtained for this specimen was(0.58) Hz.m.ANSYS finite element analysis results for different flexural thickness and lengths were obtained and have been compared to the experimental results.The effect of both the thickness and length of the flexure on a particular arrangement has been discussed.展开更多
Cubic boron nitride（c-BN） was synthesized through benzene thermal method at a lower temperature of （300℃） by selecting liquid（（C2H5）2O·）BF3 and Li3N as reactants. Hexagonal boron nitride（h-BN） and orth...Cubic boron nitride（c-BN） was synthesized through benzene thermal method at a lower temperature of （300℃） by selecting liquid（（C2H5）2O·）BF3 and Li3N as reactants. Hexagonal boron nitride（h-BN） and orthorhombic boron nitride（o-BN） were also obtained. The samples were characterized by X-ray powder diffractometry and Fourier transformation infrared spectroscopy. The results show that all the BF3, BCl3 and BBr3 in the same family compounds can react with Li3N to synthesize BN since the strongest bond of B—F can be broken. Compared with BBr3, liquid （C2H5）2O·BF3 is cheaper, less toxic and more convenient to operate. Li3N not only provides nitrogen source but also has catalytic effect on accelerating the formation of c-BN at low temperature and pressure.展开更多
OBJECTIVE Analysis of traditional Chinese medicinal(TCM)supplements has always been a laborious task,particularly in the case of multi-ingredient formulations.Traditionally,herbal extracts are analyzed using one or fe...OBJECTIVE Analysis of traditional Chinese medicinal(TCM)supplements has always been a laborious task,particularly in the case of multi-ingredient formulations.Traditionally,herbal extracts are analyzed using one or few markers compounds.In the recent years,however,pharmaceutical companies are introducing health supplements of TCM ingredients to cater to the needs of consumers in the fast-paced society in this age.As such,new problems arise in the aspects of composition identification as well as quality analysis.In most cases of products or supplements formulated with multiple TCM herbs,the chemical composition and nature of each raw material differs greatly from the others in the formulation.This results in a requirement for individual analytical processes in order to identify the marker compounds in the various botanicals.The aim of this study is to establish a rapid and low cost analytical approach using high performance thin layer chromatography(HPTLC)for the analysis of 3 key components of the LAC Liver Protector,a supplement with TCM formulation aimed at improving liver health.METHODS The TCM herbs were extracted with methods derived from Chinese Pharmacopeia standards.The herbal extracts were then applied to HPTLC plates using CAMAG Linomat 5 and developed using fully saturated twin-trough chromatographic chambers.The developed plates were derivatized and documented with CAMAG TLC Visualizer.The images were processed with CAMAG winCATS software to calculate the Rf values and confirm the presence of key constituents of the herbs.RESULTS The 3 key components of LAC Liver Protector product,namely Radix notoginseng,Rhizoma alismatis and Radix paeoniae alba/rubra were identified in all 6 batches of products tested.CONCLUSION With the increasing trend of small and medium-sized enterprises(SMEs)bringing natural products and health supplements into the market,it is crucial that the qualities of both raw materials and end products be well-assured for the protection of consumers.With the technology of HPTLC,science can be incorporated to help SMEs with their quality control,thereby ensuring product quality.展开更多
OBJECTIVE To investigate the isolation,extraction,purification,and immunomodulatory activities in vitro and in vivo of polysaccharides from four different species of Dendrobiumherbs widely used in Singapore.METHODS To...OBJECTIVE To investigate the isolation,extraction,purification,and immunomodulatory activities in vitro and in vivo of polysaccharides from four different species of Dendrobiumherbs widely used in Singapore.METHODS To apply the classic method of water extraction and ethanol precipitation and the gel column chromatography technique,the polysaccharides from four species of Dendrobium herbs(D.moniliforme,D.crystallinum,D.primulinum,D.chrysanthum)were obtained.The polysaccharides were tested first on RAW 264.7 cell line with MTT method to test the effect of polysaccharides on macrophages.The two polysaccharides from D.moniliforme were found to promote proliferation of the cells,and were then tested on mice splenocyte primary cell culture.The same polysaccharides were also injected to female BALB/c mice at various doses for 21 dto see whether they would have affected the organs,especially the livers,spleens and thymuses.RESULTS Out of the 4 Dendrobiumspecies tested,it was found that polysaccharides from D.moniliformeto be most supportive of the proliferation of macrophages in a dose-dependent manner,with increasing effect with the increasing doses used.Polysaccharides from D.chrysanthumand D.crystallinum were also found to act similarly albeit to a lesser extent.The two D.moniliforme polysaccharides were also found to greatly enhance the proliferation of mouse splenocytes in vitro and growth of the spleen in vivo.CONCLUSION The immunomodulatory activities in vitro and in vivo of polysaccharides from four species of Dendrobium herbs were different.Their diverse chemical characters might contribute to their varied bioactivity,which should be further investigated.In addition,it was suggested that the polysaccharides from D.moniliforme could be potential immunostimulants used in the healthcare and food industry.展开更多
OBJECTIVE ″-omics″study represents an unbiased perspective to examine the bio-system to discover the novel biomarker(s)which might be overlooked when targeted analysis is performed instead.Urine,due to its ease of c...OBJECTIVE ″-omics″study represents an unbiased perspective to examine the bio-system to discover the novel biomarker(s)which might be overlooked when targeted analysis is performed instead.Urine,due to its ease of collection,minimal invasion involved and rich information of the downstream metabolites,has been extensively studied.Fermentum rubrum(Hongqu,HQ capsules)is a well-known traditional medicine with the claimed slimming effect which could be related to the reduction in the deposition of total cholesterol and glycerides.Lack in sufficient clinical evidence is always one of the leading reasons that hamper traditional medicines from gaining world-wide recognition.In our pursuit of scientific support for HQ capsules in managing obesity,we aim to examine the alteration of urinary metabolites in this small-scale human clinical research.METHODS 6 Chinese subjects were included and exposed to short-term administration of HQ capsules for 3d,twice daily,two capsules each dosing.The urine samples were collected for three days prior to the dosing and on the day following the last dosing.In total,96 urine samples were collected and then separated on hydrophilic interaction chromatography(HILIC)and analyzed by Agilent 6550 ESI-Quadrupoletime-of-flight(QTOF)mass spectrometer.RESULTS Under positive mode,two compounds were found to be present only in post-dosing urine,and one compound was significantly lowered in post-dosing samples.Those two compounds might be associated with the administered HQ capsules,which is formulated with multiherbal constituents.CONCLUSION Further elucidation on the structures of these compounds is needed to enable better understanding of the mechanism of HQ capsules in managing obesity.展开更多
The optimum control strategy and the saving potential of all variable chiller plant under the conditions of changing building cooling load and cooling water supply temperature were investigated. Based on a simulation ...The optimum control strategy and the saving potential of all variable chiller plant under the conditions of changing building cooling load and cooling water supply temperature were investigated. Based on a simulation model of water source chiller plant established in dynamic transient simulation program (TRNSYS),the four-variable quadratic orthogonal regression experiments were carried out by taking cooling load,cooling water supply temperature,cooling water flow rate and chilled water flow rate as variables,and the fitting formulas expressing the relationships between the total energy consumption of chiller plant with the four selected parameters was obtained. With the SAS statistical software and MATHEMATICA mathematical software,the optimal chilled water flow rate and cooling water flow rate which result in the minimum total energy consumption were determined under continuously varying cooling load and cooling water supply temperature. With regard to a chiller plant serving an office building in Shanghai,the total energy consumptions under different control strategies were computed in terms of the forecasting function of cooling load and water source temperature. The results show that applying the optimal control strategy to the chiller plant can bring a saving of 23.27% in power compared with the corresponding conventional variable speed plant,indicating that the optimal control strategy can improve the energy efficiency of chiller plant.展开更多
There are always large-scale items in the maintenances schedule of aircraft system, many of which have been fixed to be done in predefined sequences, which leads the workflow to be sys-tematically complex and makes th...There are always large-scale items in the maintenances schedule of aircraft system, many of which have been fixed to be done in predefined sequences, which leads the workflow to be sys-tematically complex and makes this kind of problem quite different from all sorts of existing job-selection modes. On the other hand, the human resources are always limited and men have different working capabilities on different items, which make the allocation operation of human resources be much roomy. However, the final total time span of maintenance is often required to be as short as possible in many practices, in order to suffer only the lowest cost of loss while the system is stopping. A new model for op-timizing the allocation if aircraft maintenance human resources with the constraint of predefined sequence is presented. The ge-netic algorithm is employed to find the optimal solution that holds the shortest total time span of maintenance. To generate the ul-timate maintenance work items and the human resource array, the sequences among all maintenance work items are considered firstly, the work item array is then generated through traversal with the constraint of maintenance sequence matrix, and the human resources are finally allocated according to the work item array with the constraint of the maintenance capability. An example is demonstrated to show that the model and algorithm behave a satisfying performance on finding the optimal solution as expected.展开更多
Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices.In this study,polyvinyl pyrrolidone was used as a complexing agent to synthesize La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)...Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices.In this study,polyvinyl pyrrolidone was used as a complexing agent to synthesize La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3)(LSCF)perovskite oxide.The obtained porous layered LSCF has a large specific surface area of 23.74 m^(2)/g,four times higher than that prepared by the traditional sol-gel method(5.08 m^(2)/g).The oxygen reduction reaction activity of the oxide in 0.1 mol/L KOH solution was studied using a rotating ring-disk electrode.In the tests,the initial potential of 0.88 V(vs.reversible hydrogen electrode)and the limiting diffusion current density of 5.02 mA/cm^(2)were obtained at 1600 r/min.Therefore,higher catalytic activity and stability were demonstrated,compared with the preparation of LSCF perovskite oxide by the traditional method.展开更多
The factor of safety of mechanically stabilized earth(MSE) structures can be analyzed either using limit equilibrium method(LEM) or strength reduction method(SRM) in finite element/difference method. In LEM, the stren...The factor of safety of mechanically stabilized earth(MSE) structures can be analyzed either using limit equilibrium method(LEM) or strength reduction method(SRM) in finite element/difference method. In LEM, the strengths of the reinforcement members and soils are reduced with the same factor. While using the SRM, only soil strength is reduced during the calculation of the factor of safety. This causes inconsistence in calculating the factor of safety of the MSE structures. To overcome this, an iteration method is proposed to consider the strength reduction of the reinforcements in SRM. The method is demonstrated by using PLAXIS, a finite element software. The results show that the factor of safety converges after a few iterations. The reduction of strength has different effects on the factor of safety depending on the properties of the reinforcements and the soil, and failure modes.展开更多
基金Supported by the National Natural Science Foundation of China(62105039)。
文摘In the process of power scaling large-area Quantum Cascade Lasers(QCLs),challenges such as degradation of beam quality and emission of multilobed far-field modes are frequently encountered.These issues become particularly pronounced with an increase in ridge width,resulting in multimode problems.To tackle this,an innovative multi ridge waveguide structure based on the principle of supersymmetry(SUSY)was proposed.This structure comprises a wider main waveguide in the center and two narrower auxiliary waveguides on either side.The high-order modes of the main waveguide are coupled with the modes of the auxiliary waveguides through mode-matching design,and the optical loss of the auxiliary waveguides suppresses these modes,thereby achieving fundamental mode lasing of the wider main waveguide.This paper employs the finite difference eigenmode(FDE)method to perform detailed structural modeling and simulation optimization of the 4.6μm wavelength quantum cascade laser,successfully achieving a single transverse mode QCL with a ridge width of 10μm.In comparison to the traditional single-mode QCL(with a ridge width of about 5μm),the MRW structure has the potential to increase the gain area of the laser by 100%.This offers a novel design concept and methodology for enhancing the single-mode luminous power of mid-infrared quantum cascade lasers,which is of considerable significance.
文摘Micro Aerial Vehicles(MAVs) are the smallest artificial aircraft.Most of the flapping wings MAVs are powered by electric motors of various capacities.We report in this paper the application of piezoelectric actuators as power system for a flapping wing MAV using a compliant displacement amplification mechanism.The actuator used for this application is a pre-stressed cut piece of TH-7R type Thunder actuator.A two-bar compliant mechanism with two flexures has been developed to convert the linear displacement into angular movement and amplification.The specimens were made from carbon fiber links and nylon flexures.We also proposed to use the product of frequency(F) and tip displacement(D), F * D as a criteria for the characterization of an amplifying mechanism.The best specimen according to this criterion is obtained for a 5mm length flexure specimen made of three layers of nylon.The F*D value obtained for this specimen was(0.58) Hz.m.ANSYS finite element analysis results for different flexural thickness and lengths were obtained and have been compared to the experimental results.The effect of both the thickness and length of the flexure on a particular arrangement has been discussed.
基金Projects(2027300750372006) supported by the National Natural Science Foundation of China
文摘Cubic boron nitride（c-BN） was synthesized through benzene thermal method at a lower temperature of （300℃） by selecting liquid（（C2H5）2O·）BF3 and Li3N as reactants. Hexagonal boron nitride（h-BN） and orthorhombic boron nitride（o-BN） were also obtained. The samples were characterized by X-ray powder diffractometry and Fourier transformation infrared spectroscopy. The results show that all the BF3, BCl3 and BBr3 in the same family compounds can react with Li3N to synthesize BN since the strongest bond of B—F can be broken. Compared with BBr3, liquid （C2H5）2O·BF3 is cheaper, less toxic and more convenient to operate. Li3N not only provides nitrogen source but also has catalytic effect on accelerating the formation of c-BN at low temperature and pressure.
文摘OBJECTIVE Analysis of traditional Chinese medicinal(TCM)supplements has always been a laborious task,particularly in the case of multi-ingredient formulations.Traditionally,herbal extracts are analyzed using one or few markers compounds.In the recent years,however,pharmaceutical companies are introducing health supplements of TCM ingredients to cater to the needs of consumers in the fast-paced society in this age.As such,new problems arise in the aspects of composition identification as well as quality analysis.In most cases of products or supplements formulated with multiple TCM herbs,the chemical composition and nature of each raw material differs greatly from the others in the formulation.This results in a requirement for individual analytical processes in order to identify the marker compounds in the various botanicals.The aim of this study is to establish a rapid and low cost analytical approach using high performance thin layer chromatography(HPTLC)for the analysis of 3 key components of the LAC Liver Protector,a supplement with TCM formulation aimed at improving liver health.METHODS The TCM herbs were extracted with methods derived from Chinese Pharmacopeia standards.The herbal extracts were then applied to HPTLC plates using CAMAG Linomat 5 and developed using fully saturated twin-trough chromatographic chambers.The developed plates were derivatized and documented with CAMAG TLC Visualizer.The images were processed with CAMAG winCATS software to calculate the Rf values and confirm the presence of key constituents of the herbs.RESULTS The 3 key components of LAC Liver Protector product,namely Radix notoginseng,Rhizoma alismatis and Radix paeoniae alba/rubra were identified in all 6 batches of products tested.CONCLUSION With the increasing trend of small and medium-sized enterprises(SMEs)bringing natural products and health supplements into the market,it is crucial that the qualities of both raw materials and end products be well-assured for the protection of consumers.With the technology of HPTLC,science can be incorporated to help SMEs with their quality control,thereby ensuring product quality.
基金The project supported by The Ministry of Education Translational R&D and Innovation Fund(MOE2012-TIF-1-G-065),Singapore
文摘OBJECTIVE To investigate the isolation,extraction,purification,and immunomodulatory activities in vitro and in vivo of polysaccharides from four different species of Dendrobiumherbs widely used in Singapore.METHODS To apply the classic method of water extraction and ethanol precipitation and the gel column chromatography technique,the polysaccharides from four species of Dendrobium herbs(D.moniliforme,D.crystallinum,D.primulinum,D.chrysanthum)were obtained.The polysaccharides were tested first on RAW 264.7 cell line with MTT method to test the effect of polysaccharides on macrophages.The two polysaccharides from D.moniliforme were found to promote proliferation of the cells,and were then tested on mice splenocyte primary cell culture.The same polysaccharides were also injected to female BALB/c mice at various doses for 21 dto see whether they would have affected the organs,especially the livers,spleens and thymuses.RESULTS Out of the 4 Dendrobiumspecies tested,it was found that polysaccharides from D.moniliformeto be most supportive of the proliferation of macrophages in a dose-dependent manner,with increasing effect with the increasing doses used.Polysaccharides from D.chrysanthumand D.crystallinum were also found to act similarly albeit to a lesser extent.The two D.moniliforme polysaccharides were also found to greatly enhance the proliferation of mouse splenocytes in vitro and growth of the spleen in vivo.CONCLUSION The immunomodulatory activities in vitro and in vivo of polysaccharides from four species of Dendrobium herbs were different.Their diverse chemical characters might contribute to their varied bioactivity,which should be further investigated.In addition,it was suggested that the polysaccharides from D.moniliforme could be potential immunostimulants used in the healthcare and food industry.
基金The project supported by Temasek Polytechnic DRP project grant
文摘OBJECTIVE ″-omics″study represents an unbiased perspective to examine the bio-system to discover the novel biomarker(s)which might be overlooked when targeted analysis is performed instead.Urine,due to its ease of collection,minimal invasion involved and rich information of the downstream metabolites,has been extensively studied.Fermentum rubrum(Hongqu,HQ capsules)is a well-known traditional medicine with the claimed slimming effect which could be related to the reduction in the deposition of total cholesterol and glycerides.Lack in sufficient clinical evidence is always one of the leading reasons that hamper traditional medicines from gaining world-wide recognition.In our pursuit of scientific support for HQ capsules in managing obesity,we aim to examine the alteration of urinary metabolites in this small-scale human clinical research.METHODS 6 Chinese subjects were included and exposed to short-term administration of HQ capsules for 3d,twice daily,two capsules each dosing.The urine samples were collected for three days prior to the dosing and on the day following the last dosing.In total,96 urine samples were collected and then separated on hydrophilic interaction chromatography(HILIC)and analyzed by Agilent 6550 ESI-Quadrupoletime-of-flight(QTOF)mass spectrometer.RESULTS Under positive mode,two compounds were found to be present only in post-dosing urine,and one compound was significantly lowered in post-dosing samples.Those two compounds might be associated with the administered HQ capsules,which is formulated with multiherbal constituents.CONCLUSION Further elucidation on the structures of these compounds is needed to enable better understanding of the mechanism of HQ capsules in managing obesity.
基金Project(G-0805-10156) supported by US Energy Foundation
文摘The optimum control strategy and the saving potential of all variable chiller plant under the conditions of changing building cooling load and cooling water supply temperature were investigated. Based on a simulation model of water source chiller plant established in dynamic transient simulation program (TRNSYS),the four-variable quadratic orthogonal regression experiments were carried out by taking cooling load,cooling water supply temperature,cooling water flow rate and chilled water flow rate as variables,and the fitting formulas expressing the relationships between the total energy consumption of chiller plant with the four selected parameters was obtained. With the SAS statistical software and MATHEMATICA mathematical software,the optimal chilled water flow rate and cooling water flow rate which result in the minimum total energy consumption were determined under continuously varying cooling load and cooling water supply temperature. With regard to a chiller plant serving an office building in Shanghai,the total energy consumptions under different control strategies were computed in terms of the forecasting function of cooling load and water source temperature. The results show that applying the optimal control strategy to the chiller plant can bring a saving of 23.27% in power compared with the corresponding conventional variable speed plant,indicating that the optimal control strategy can improve the energy efficiency of chiller plant.
文摘There are always large-scale items in the maintenances schedule of aircraft system, many of which have been fixed to be done in predefined sequences, which leads the workflow to be sys-tematically complex and makes this kind of problem quite different from all sorts of existing job-selection modes. On the other hand, the human resources are always limited and men have different working capabilities on different items, which make the allocation operation of human resources be much roomy. However, the final total time span of maintenance is often required to be as short as possible in many practices, in order to suffer only the lowest cost of loss while the system is stopping. A new model for op-timizing the allocation if aircraft maintenance human resources with the constraint of predefined sequence is presented. The ge-netic algorithm is employed to find the optimal solution that holds the shortest total time span of maintenance. To generate the ul-timate maintenance work items and the human resource array, the sequences among all maintenance work items are considered firstly, the work item array is then generated through traversal with the constraint of maintenance sequence matrix, and the human resources are finally allocated according to the work item array with the constraint of the maintenance capability. An example is demonstrated to show that the model and algorithm behave a satisfying performance on finding the optimal solution as expected.
基金Project(20192BAB216015)supported by the Science and Technology Program of Jiangxi Province,ChinaProjects(GJJ180464,GJJ171499)supported by the Science and Technology Program of Education Department of Jiangxi Province,China+2 种基金Project(jxxjbs17057)supported by the Scientific Research Foundation of Jiangxi University of Science and Technology,ChinaProject([2018]50)supported by the Key R&D Programs of Science and Technology Project of Ganzhou City,ChinaProject([2017]179)supported by the Science and Technology Project of Ganzhou City,China。
文摘Low-cost catalysts with high activity are in immediate demand for energy storage and conversion devices.In this study,polyvinyl pyrrolidone was used as a complexing agent to synthesize La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3)(LSCF)perovskite oxide.The obtained porous layered LSCF has a large specific surface area of 23.74 m^(2)/g,four times higher than that prepared by the traditional sol-gel method(5.08 m^(2)/g).The oxygen reduction reaction activity of the oxide in 0.1 mol/L KOH solution was studied using a rotating ring-disk electrode.In the tests,the initial potential of 0.88 V(vs.reversible hydrogen electrode)and the limiting diffusion current density of 5.02 mA/cm^(2)were obtained at 1600 r/min.Therefore,higher catalytic activity and stability were demonstrated,compared with the preparation of LSCF perovskite oxide by the traditional method.
基金Project(41072200)supported by the National Natural Science Foundation of ChinaProject(14PJD032)supported by the Shanghai Pujiang Program,China
文摘The factor of safety of mechanically stabilized earth(MSE) structures can be analyzed either using limit equilibrium method(LEM) or strength reduction method(SRM) in finite element/difference method. In LEM, the strengths of the reinforcement members and soils are reduced with the same factor. While using the SRM, only soil strength is reduced during the calculation of the factor of safety. This causes inconsistence in calculating the factor of safety of the MSE structures. To overcome this, an iteration method is proposed to consider the strength reduction of the reinforcements in SRM. The method is demonstrated by using PLAXIS, a finite element software. The results show that the factor of safety converges after a few iterations. The reduction of strength has different effects on the factor of safety depending on the properties of the reinforcements and the soil, and failure modes.
