This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the acc...This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.展开更多
A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electric...A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electrical resistivity and ultrasonic equipment.Results show that:1)Uniaxial compressive strength(UCS)and elastic modulus(EM)of the samples curing under pressure are higher than those of the control samples without pressure,ranging in ratio from 0.5%to 20.2%and 7.1%to 52.3%,respectively,and are influenced by the initial loading age(ILA)and stress strength ratio(SSR).The SSR during curing should not exceed 80%.2)The earlier the ILA is,the higher the total strain becomes.The higher the SSR applies,the larger the total strain gets.The creep strain increases with the increase of SSR and can be described by Burger’s viscoelastic creep model.When SSR is less than 80%,the earlier the ILA is,the smaller the creep strain becomes after the last step-loading.3)The stability of the early age backfill column under pressure can be monitored based on the change of ultrasonic pulse velocity(UPV)and electrical resistivity.展开更多
A three-dimensional(3D)step-by-step inversion strategy for audio magnetotellurics(AMT)is investigated in this study.The objective function is minimized by iteratively solving the Gauss-Newton normal equation,and the i...A three-dimensional(3D)step-by-step inversion strategy for audio magnetotellurics(AMT)is investigated in this study.The objective function is minimized by iteratively solving the Gauss-Newton normal equation,and the inversion region is discretized with unstructured tetrahedral elements.The inversion proceeds step-by-step from a coarse mesh to a fine mesh.In the inversion iteration process,a mesh is adaptively optimized according to the spatial gradient information about the model resistivity to fine delineate the boundaries of abnormal bodies.In the early stage of inversion execution,a coarse mesh is used for inversion,and the inversion stability is improved by reducing the number of inversion elements.In addition,mesh refinement is performed in the iterative inversion process.The inversion results obtained from the previous mesh are used as the reference and initial models for the next mesh iterative inversion.The step-by-step inversion strategy can ensure that the inversion is performed in the correct direction,improving the inversion stability and results gradually.Synthetic results show that the step-by-step inversion strategy with a Gauss-Newton method for 3D AMT inversion is stable and reliable,which lays a foundation for further practical 3D AMT data inversion.展开更多
In recent years,oil spill accidents occur frequently in the marine area of China.Finding out the spilled oil source is a key step in the relevant investigation.In this paper,a step-by-step fingerprinting identificatio...In recent years,oil spill accidents occur frequently in the marine area of China.Finding out the spilled oil source is a key step in the relevant investigation.In this paper,a step-by-step fingerprinting identification method was used in a spilled oil accident in the Bohai Sea in 2002.Advanced chemical fingerprinting and data interpretation techniques were used to characterize the chemical composition and determine the possible sources of two spilled oil samples.The original gas chromatography -flame ionization detec-tion (GC-FID) chromatogram of saturated hydrocarbons was compared.The gas chromatography-mass spectrometry (GC/MS) chromatograms of aromatic hydrocarbons terpane and sterane,n-alkane and poly-aromatic hydrocarbons (PAHs) were analyzed.The correlation analysis on diagnostic ratios was performed with Student’s t-test.It is found that the oil fingerprinting of the spilled oil (designated as sz1) from the polluted sand beach was identical with the suspected oil (designated as ky1) from a nearby crude oil refinery factory.They both showed the fingerprinting character of mixed oil.The oil fingerprinting of the spilled oil (designated as ms1) collected from the port was significantly different from oil ky1 and oil sz1 and was with a lubricating oil fingerprint character.The identification result not only gave support for the spilled oil investigation,but also served as an example for studying spilled oil accidents.展开更多
We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve param...We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.展开更多
Objective: To evaluate the treatment outcomes of patients with pelvic ring injury by applying step-by-step external pelvic fixation and circular external fixation device.Methods: A total of 28 patients suffering from ...Objective: To evaluate the treatment outcomes of patients with pelvic ring injury by applying step-by-step external pelvic fixation and circular external fixation device.Methods: A total of 28 patients suffering from disintegrated pelvic ring injury are involved in the study. Fourteen patients(the treatment group) underwent step-by-step external pelvic fixation by applying anterior(anti-shock) and posterior modules. For the rest 14 patients(the experimental group), the osteosynthesis were conducted by means of a circular external fixation device. The long-term outcomes were evaluated in a year after the injury.Results: The residual deformity of 5(4–7) mm was observed in 10 patients(71.4%) from the experimental group. In the treatment group, the residual deformity was evident only in 4(28.6%) cases being 2.5(2–3) mm(P = 0.000 319) on the average. The functional result(according to the Majeed scale) was statistically better in the treatment group(P = 0.000 319). Nine(64.3%) and five(35.7%) patients in treatment group showed excellent and positive results, respectively. The excellent result was demonstrated by 3patients(21.4%) of the experimental group, the positive outcomes were observed in 6 cases(42.9%) and the unsatisfactory one was displayed by 1 patient(7.1%) of the same group.Conclusions: The modular approach applied is the advantage of the transosseous osteosynthesis allowing for a separate anterior(anti-shock) fixation and final posterior reposition of the pelvic ring preceded by the stabilization of vital functions. The above mentioned method gives an opportunity to increase the amount of techniques applied for the pelvic external fixation in polytrauma cases.展开更多
A new active control method was proposed, in which the analytical control law was deduced by using a step by step integral method to differential equation of motion under the condition of static error being zero. This...A new active control method was proposed, in which the analytical control law was deduced by using a step by step integral method to differential equation of motion under the condition of static error being zero. This control law is terse in mathematical expression and convenient for practical use. The simulation results demonstrate that the proposed method can provide much more remarkable peak response reduction of seismically excited structures than the classical LQR method.展开更多
A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved ...A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved using an energy equation and the calculating data of the original method. The method presented is better than the original method in terms of calculating postulations and is in better conformity with the system's movement. Take the Wilson-θ method as an example. By using the coordination process, the calculation precision has been greatly im proved (reducing the errors by approximately 90% ), and the greater part of overshooting of the calculation result has been eliminated. The study suggests that the mal-coordination of the motion parameters within the time-step is the major factor that contributes to the result errors of step-by-step integration for the dynamic equation.展开更多
A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentration...A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentrations less than 10-6 mol·L-1 do not activate any chemical reaction. So, within each step, the time steplength Δt of the algorithm is determined from the fastest reaction rate maxR by the formula Δt = 10-6mol·L-1/max R. All the reversible elementary reactions occur simultaneously;however, by a simple book-keeping technique, the updating of species concentrations, within each step of the algorithm, is performed within each elementary reaction separately. The above proposed simple algorithm for Chemical Kinetics is applied to a simple model for hydrogen combustion with only five reversible elementary reactions (Initiation, Propagation, First and Second Branching, Termination by wall destruction) with six species (H2, O2, H, O, HO, H2O). These five reversible reactions are recommended in the literature as the most significant elementary reactions of hydrogen combustion [1] [2]. Based on the proposed here simple algorithm for Chemical Kinetics, applied to the global mechanism of proposed five reversible elementary reactions for hydrogen combustion, a simple and short computer program has been developed with only about 120 Fortran instructions. By this proposed program, the following are obtained: 1) The total species concentration of hydrogen combustion, starting from the sum of initial reactants concentrations [H2] + [O2], gradually diminishes, due to termination reaction by wall destruction, and tends to the final concentration of the product [H2O], that is to the 2/3 of its initial value, in accordance to the established overall stoichiometric reaction of hydrogen combustion 2H2 + O2 → 2H2O. 2) Time-histories for concentrations of main species H2, O2, H, H2O of hydrogen combustion, in explosion and equilibrium regions, obtained by the proposed program, are compared to corresponding ones obtained by accurate computational studies of [3]. 3) In the first step of the algorithm, the only nonzero species concentrations are those of reactants [H2], [O2]. So, the maximum reaction rate is that of the forward initiation reaction max R = Rif = kif[H2] [O2], where the rate constant kif is very slow. Thus, the first time steplength Δt1 = 10-6mol·L-1/max R results long in sec. After the first step, the sequences of all the following Δt’s are very short, in μsec. So, the first time steplength Δt1 can be considered as ignition delay time. 4) It is assumed that explosion corresponds to ignition delay time Δt1 t1 = 10 sec., can be considered as explosion limit curve. This curve is compared to the corresponding one obtained by the accurate computational studies of [2].展开更多
In order to improve the design and research and development (R & D) efficiency of the pressure- compensating drip irrigation emitter,a step-by-step computational fluid dynamics (CFD) design method was proposed bas...In order to improve the design and research and development (R & D) efficiency of the pressure- compensating drip irrigation emitter,a step-by-step computational fluid dynamics (CFD) design method was proposed based on CFD theory combined with the finite element method. By analyzing its hydraulic performance through the step-by-step CFD method,the prediction pressure-flow curve(p-Q curve) of the pressure-compensating emitter was obtained. Then the test samples were fabricated using rapid prototype and manufacturing(RP & M) technology. The emitters' hydraulic performance experiment was carried out and the experimental p-Q curve was obtained. The step-by-step CFD design method was verified by comparing the experimental p-Q curve with the prediction values,which showed that the prediction values met the experimental results well within the normal range of the emitter's working pressure. On this basis,the effect of the emitter structure on its pressure-compensating performance was studied,which showed that the height of the pressure-compensating region had significant effects on the emitter's pressure-compensating performance. Series products of the pressure-compensating emitter could be designed by changing the region's height.展开更多
Objective: Using the nursing methods in the title, to further explore the postoperative recovery of the fracture patients mentioned this time, in order to clarify the influence of nursing on them. Methods: Lumbar comp...Objective: Using the nursing methods in the title, to further explore the postoperative recovery of the fracture patients mentioned this time, in order to clarify the influence of nursing on them. Methods: Lumbar compression fracture is the main figure in this study, and the whole process is carried out around it. By implementing the nursing methods in the topic, the rehabilitation process is shortened. Results: After the rational application of the nursing methods in this study in clinic, the patients recovery has changed, with JOA and other excellent scores as the performance. The quality of life has been improved accordingly, and the patients impression of medical staff has been improved, so their dissatisfaction has gradually decreased. Conclusion: After the research, through the analysis of the results, it is suggested that the nursing methods used can have a positive impact on the postoperative rehabilitation of the key figures in this research.展开更多
Currently,chemotherapy is the main clinical therapy of tumors.Depressingly,most chemotherapeutic drugs such as doxorubicin and paclitaxel(PTX)have poor water solubility,leading to low bioavailability and serious side ...Currently,chemotherapy is the main clinical therapy of tumors.Depressingly,most chemotherapeutic drugs such as doxorubicin and paclitaxel(PTX)have poor water solubility,leading to low bioavailability and serious side effects.Till now,although a variety of nanoparticulate drug delivery systems have been designed to ameliorate the above disadvantage of chemotherapy drugs,their application is still severely limited due to the complex preparation,poor stability,low drug loading,and premature drug release.Herein,a metal phenolic network-based drug delivery system with superior stability,satisfactory drug loading capacity,good biocompatibility,reduced undesired premature release,and excellent anti-tumor ability has been established for achieving step-by-step multiple stimuli-responsive drug delivery.Firstly,the redox-responsive dimeric paclitaxel(diPTX)prodrug was synthesized.Then diPTX@Fe&tannic acid(diPTX@Fe&TA)complex nanoparticles with satisfactory PTX loading capacity were obtained by deposition of Fe&TA network complex on the nanocore of diPTX rapidly with a simple method.The diPTX@Fe&TA nanoparticles have a hydrodynamic diameter of 152.6±1.2 nm,long-term colloidal stability,and high PTX loading content of 24.7%.Besides,diPTX@Fe&TA could expose to the acidic lysosomal environment and the reduction cytoplasmic environment continuously,resulting in the sequential release of diPTX and PTX when it was phagocytosed by tumor cells.Meanwhile,PTX showed almost no release under physiological condition(pH 7.4),which effectively inhibited the undesirable premature release of PTX.More importantly,diPTX@Fe&TA could suppress the growth of tumor effectively in vivo,along with negligible toxicity for organs.This work developed a simple and novel approach for the construction of a stepwise multiple stimuli-responsive drug delivery system with superior stability and satisfactory drug loading capacity to inhibit tumor growth effectively.展开更多
The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansio...The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansion of strip samples was measured using a linear dilatometer during the staged reduction process at a temperature of 900℃.The existence states of MgO in hematite,magnetite,and wüstite were investigated through thermodynamic calculations.The magnetite strip samples were subjected to oxidizing roasting at 1250℃ for 30 min to produce hematite strip samples.The strip samples with 0.49,1.49,2.49,and 3.49 wt.%MgO were analyzed for length change.It was observed that the sample with 2.49 wt.%MgO exhibited the least significant length change.The lengths of the samples with the initial length being 20 mm before reduction changed during the reduction stages of Fe_(2)O_(3)→Fe_(3)O_(4),Fe_(3)O_(4)→FeO,and FeO→Fe were 615,−25,and−378μm,respectively.The volume expansion of hematite to magnetite was primarily attributed to the crystal transformation.During the reduction stage from wüstite to metallic iron,a substantial contraction occurred,while the slag phase was able to retain its original basic shape.The enclosed areas,as indicated by the expansion change curves of the samples with 0.49,1.49,2.49,and 3.49 wt.%MgO,were measured at 3.76×10^(6),3.23×10^(6),3.05×10^(6),and 3.17×10^(6)μm s,respectively.展开更多
Dynamic wake field information is vital for the optimized design and control of wind farms.Combined with sparse measurement data from light detection and ranging(LiDAR),the physics-informed neural network(PINN)framewo...Dynamic wake field information is vital for the optimized design and control of wind farms.Combined with sparse measurement data from light detection and ranging(LiDAR),the physics-informed neural network(PINN)frameworks have recently been employed for forecasting freestream wind and wake fields.However,these PINN frameworks face challenges of low prediction accuracy and long training times.Therefore,this paper constructed a PINN framework for dynamic wake field prediction by integrating two accuracy improvement strategies and a step-by-step training time saving strategy.The results showed that the different performance improvement routes significantly improved the overall performance of the PINN.The accuracy and efficiency of the PINN with spatiotemporal improvement strategies were validated via LiDAR-measured data from a wind farm in Shandong province,China.This paper sheds light on load reduction,efficiency improvement,intelligent operation and maintenance of wind farms.展开更多
As all generators are distributed in different areas among large scale power systems,the cooperative manipulation of the multi-generator system cannot operate well without consideration of the distance information of ...As all generators are distributed in different areas among large scale power systems,the cooperative manipulation of the multi-generator system cannot operate well without consideration of the distance information of the generators.A distributed step-by-step finite-time consensus scheme for the heterogeneous battery energy storage system(BESS)is proposed in this paper,where the coordinated consensus can come into reality within a limited time,which is appealing for the electrical engineering community.To be concrete,at first,all BESSs are classified into several clusters according to their locations,and in each cluster,there is an active leader in charge of information receiving from outside.Then,in order to coordinate the multi BESSs,five inputs,which are function oriented,were used to achieve energy level balancing,active/reactive power sharing,and the consensus of voltage and frequency of the multi BESSs.Furthermore,the frequency and voltage restoration to the nominal values of the main grid were made possible by the introduction of a virtual leader,which is actually an external leader.Compared with the centralized methods,this control scheme is entirely distributed,and each BESS only utilizes the information of its own and its neighbors.In addition,this control is robust to the load perturbation and the plug-and-play of the communication topology.Finally,some simulation experiments are executed on the modified IEEE 57-bus system to verify the suggested scheme.展开更多
We propose a pipelined Reed-Solomon(RS) decoder for an ultra-wideband system using a modified stepby-step algorithm. To reduce the complexity, the modified step-by-step algorithm merges two cases of the original algor...We propose a pipelined Reed-Solomon(RS) decoder for an ultra-wideband system using a modified stepby-step algorithm. To reduce the complexity, the modified step-by-step algorithm merges two cases of the original algorithm. The pipelined structure allows the decoder to work at high rates with minimum delay. Consequently, for RS(23,17) codes, the proposed architecture requires 42.5% and 24.4% less area compared with a modified Euclidean architecture and a pipelined degree-computationless modified Euclidean architecture, respectively. The area of the proposed decoder is 11.3% less than that of the previous step-by-step decoder with a lower critical path delay.展开更多
The primary aim of the study was to prepare narrow sized polymeric nanoparticles by implementing few modifications to the conventional nanoprecipitation technique and to evaluate the effect of various process paramete...The primary aim of the study was to prepare narrow sized polymeric nanoparticles by implementing few modifications to the conventional nanoprecipitation technique and to evaluate the effect of various process parameters on prepared polymeric nanoparticles.Eudragit E 100 nanoparticles were prepared by modified nanoprecipitation technique and step-by-step optimization was carried out to evaluate the effect of various process parameters such as organic solvent,polymer concentration,percentage of organic solvent,mode of addition of organic solvent in to aqueous phase,volume of aqueous phase,poloxamer 188 concentration,β-cyclodextrin concentration,temperature generated during sonication process,sonication duration,and drug concentration on the particle size,surface area,distribution width and uniformity of the prepared nanoparticles.The optimized process parameters were implemented to fabricate dual drug loaded Eudragit E 100 nanoparticles which were spherical in shape with mean particle size in the range of 118 to 140 nm,polydispersity index in the range of 0.187 to 0.254 and zeta potential in the range of 16.6 to 28.8 mV.Thus developed modified nanoprecipitation method can be used to fabricate narrow sized polymeric nanoparticles.展开更多
对码长n=2m-1纠两个错误的二进制BCH码,本文介绍了一种新的step by step译码算法。译码算法能直接确定接收的比特是否正确而不需要知道接收矢量的错误数目,也不需要知道相应的错误位置多项式。基于这种译码算法的译码器的优点在于占用...对码长n=2m-1纠两个错误的二进制BCH码,本文介绍了一种新的step by step译码算法。译码算法能直接确定接收的比特是否正确而不需要知道接收矢量的错误数目,也不需要知道相应的错误位置多项式。基于这种译码算法的译码器的优点在于占用硬件资源最少,实现简单快速。此外,这种译码方法特别适合于长码。展开更多
基金supported by the Advance Research Project of Civil Aerospace Technology(Grant No.D020304)National Nat-ural Science Foundation of China(Grant Nos.52205257 and U22B2083).
文摘This paper proposes a new step-by-step Chebyshev space-time spectral method to analyze the force vibration of functionally graded material structures.Although traditional space-time spectral methods can reduce the accuracy mismatch between tem-poral low-order finite difference and spatial high-order discre tization,the ir time collocation points must increase dramatically to solve highly oscillatory solutions of structural vibration,which results in a surge in computing time and a decrease in accuracy.To address this problem,we introduced the step-by-step idea in the space-time spectral method.The Chebyshev polynomials and Lagrange's equation were applied to derive discrete spatial goverming equations,and a matrix projection method was used to map the calculation results of prev ious steps as the initial conditions of the subsequent steps.A series of numerical experiments were carried out.The results of the proposed method were compared with those obtained by traditional space-time spectral methods,which showed that higher accuracy could be achieved in a shorter computation time than the latter in highly oscillatory cases.
基金Project(51974192)supported by the National Natural Science Foundation of ChinaProject(201803D31044)supported by the Program for Key Research Project of Shanxi Province in the Field of Social Development,ChinaProject(201801D121092)supported by the Applied Basic Research Project of Shanxi Province,China。
文摘A step-by-step load was utilized to mimic the load history of the backfill column in the in-situ curing process.The inner damage of the specimen during curing and uniaxial compressive testing was monitored by electrical resistivity and ultrasonic equipment.Results show that:1)Uniaxial compressive strength(UCS)and elastic modulus(EM)of the samples curing under pressure are higher than those of the control samples without pressure,ranging in ratio from 0.5%to 20.2%and 7.1%to 52.3%,respectively,and are influenced by the initial loading age(ILA)and stress strength ratio(SSR).The SSR during curing should not exceed 80%.2)The earlier the ILA is,the higher the total strain becomes.The higher the SSR applies,the larger the total strain gets.The creep strain increases with the increase of SSR and can be described by Burger’s viscoelastic creep model.When SSR is less than 80%,the earlier the ILA is,the smaller the creep strain becomes after the last step-loading.3)The stability of the early age backfill column under pressure can be monitored based on the change of ultrasonic pulse velocity(UPV)and electrical resistivity.
文摘A three-dimensional(3D)step-by-step inversion strategy for audio magnetotellurics(AMT)is investigated in this study.The objective function is minimized by iteratively solving the Gauss-Newton normal equation,and the inversion region is discretized with unstructured tetrahedral elements.The inversion proceeds step-by-step from a coarse mesh to a fine mesh.In the inversion iteration process,a mesh is adaptively optimized according to the spatial gradient information about the model resistivity to fine delineate the boundaries of abnormal bodies.In the early stage of inversion execution,a coarse mesh is used for inversion,and the inversion stability is improved by reducing the number of inversion elements.In addition,mesh refinement is performed in the iterative inversion process.The inversion results obtained from the previous mesh are used as the reference and initial models for the next mesh iterative inversion.The step-by-step inversion strategy can ensure that the inversion is performed in the correct direction,improving the inversion stability and results gradually.Synthetic results show that the step-by-step inversion strategy with a Gauss-Newton method for 3D AMT inversion is stable and reliable,which lays a foundation for further practical 3D AMT data inversion.
文摘In recent years,oil spill accidents occur frequently in the marine area of China.Finding out the spilled oil source is a key step in the relevant investigation.In this paper,a step-by-step fingerprinting identification method was used in a spilled oil accident in the Bohai Sea in 2002.Advanced chemical fingerprinting and data interpretation techniques were used to characterize the chemical composition and determine the possible sources of two spilled oil samples.The original gas chromatography -flame ionization detec-tion (GC-FID) chromatogram of saturated hydrocarbons was compared.The gas chromatography-mass spectrometry (GC/MS) chromatograms of aromatic hydrocarbons terpane and sterane,n-alkane and poly-aromatic hydrocarbons (PAHs) were analyzed.The correlation analysis on diagnostic ratios was performed with Student’s t-test.It is found that the oil fingerprinting of the spilled oil (designated as sz1) from the polluted sand beach was identical with the suspected oil (designated as ky1) from a nearby crude oil refinery factory.They both showed the fingerprinting character of mixed oil.The oil fingerprinting of the spilled oil (designated as ms1) collected from the port was significantly different from oil ky1 and oil sz1 and was with a lubricating oil fingerprint character.The identification result not only gave support for the spilled oil investigation,but also served as an example for studying spilled oil accidents.
基金supported by the Science and Technology Project of Guangdong Province of China(Nos.2014A020213016,2014A020212445)the University-enterprise Joint Research Project"Intelligent detection network technology joint research centre"(No.40115031).
文摘We applied near-infrared(NIR)spectroscopy with chemometrics for the rapid and reagent-fee analysis of serum urea nitrogen(SUN).The modeling is based on the average effect of multiple sample partitions to achieve parameter selection with stability.A multiparameter optimization platform with Norris derivative filter-partial least squares(Norris-PLS)was developed to select the most suitable mode(d=2,s=33,g=15).Using equidistant combination PLS(EC-PLS)with four parameters(initial wavelength I,number of wavelengths N,number of wavelength gaps G and latent variables LV),we performed wavelength screening after eliminating high-absorption wavebands.The optimal EC-PLS parameters were I=1228 nm,N=26,G=16 and LV=12.The root-mean square error(SEP),correlation coefficient(R_(p))for prediction and ratio of performance-to-deviation(RPD)for validation were 1.03 mmol L^(-1),0.992 and 7.6,respectively.We proposed the wavelength step-by-step phase-out PLS(WSP-PLS)to remove redun-dant wavelengths in the top 100 EC-PLS models with improved prediction performance.The combination of 19 wavelengths was identifed as the optimal model for SUN.The SEP,Rp and RPD in validation were 1.01 mmol L^(-1),0.992 and 7.7,respectively.The prediction effect and wavelength complexity were better than those of EC-PIS.Our results showed that NIR spectroscopy combined with the EC-PLS and WSP-PLS methods enabled the high-precision analysis ofSUN.WSP-PLS is a secondary optimization method that can further optimize any wavelength moc odel obtained through other continuous or discrete strategies to establish a simple and better model.
文摘Objective: To evaluate the treatment outcomes of patients with pelvic ring injury by applying step-by-step external pelvic fixation and circular external fixation device.Methods: A total of 28 patients suffering from disintegrated pelvic ring injury are involved in the study. Fourteen patients(the treatment group) underwent step-by-step external pelvic fixation by applying anterior(anti-shock) and posterior modules. For the rest 14 patients(the experimental group), the osteosynthesis were conducted by means of a circular external fixation device. The long-term outcomes were evaluated in a year after the injury.Results: The residual deformity of 5(4–7) mm was observed in 10 patients(71.4%) from the experimental group. In the treatment group, the residual deformity was evident only in 4(28.6%) cases being 2.5(2–3) mm(P = 0.000 319) on the average. The functional result(according to the Majeed scale) was statistically better in the treatment group(P = 0.000 319). Nine(64.3%) and five(35.7%) patients in treatment group showed excellent and positive results, respectively. The excellent result was demonstrated by 3patients(21.4%) of the experimental group, the positive outcomes were observed in 6 cases(42.9%) and the unsatisfactory one was displayed by 1 patient(7.1%) of the same group.Conclusions: The modular approach applied is the advantage of the transosseous osteosynthesis allowing for a separate anterior(anti-shock) fixation and final posterior reposition of the pelvic ring preceded by the stabilization of vital functions. The above mentioned method gives an opportunity to increase the amount of techniques applied for the pelvic external fixation in polytrauma cases.
文摘A new active control method was proposed, in which the analytical control law was deduced by using a step by step integral method to differential equation of motion under the condition of static error being zero. This control law is terse in mathematical expression and convenient for practical use. The simulation results demonstrate that the proposed method can provide much more remarkable peak response reduction of seismically excited structures than the classical LQR method.
文摘A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved using an energy equation and the calculating data of the original method. The method presented is better than the original method in terms of calculating postulations and is in better conformity with the system's movement. Take the Wilson-θ method as an example. By using the coordination process, the calculation precision has been greatly im proved (reducing the errors by approximately 90% ), and the greater part of overshooting of the calculation result has been eliminated. The study suggests that the mal-coordination of the motion parameters within the time-step is the major factor that contributes to the result errors of step-by-step integration for the dynamic equation.
文摘A simple algorithm is proposed for step-by-step time integration of stiff ODEs in Chemical Kinetics. No predictor-corrector technique is used within each step of the algorithm. It is assumed that species concentrations less than 10-6 mol·L-1 do not activate any chemical reaction. So, within each step, the time steplength Δt of the algorithm is determined from the fastest reaction rate maxR by the formula Δt = 10-6mol·L-1/max R. All the reversible elementary reactions occur simultaneously;however, by a simple book-keeping technique, the updating of species concentrations, within each step of the algorithm, is performed within each elementary reaction separately. The above proposed simple algorithm for Chemical Kinetics is applied to a simple model for hydrogen combustion with only five reversible elementary reactions (Initiation, Propagation, First and Second Branching, Termination by wall destruction) with six species (H2, O2, H, O, HO, H2O). These five reversible reactions are recommended in the literature as the most significant elementary reactions of hydrogen combustion [1] [2]. Based on the proposed here simple algorithm for Chemical Kinetics, applied to the global mechanism of proposed five reversible elementary reactions for hydrogen combustion, a simple and short computer program has been developed with only about 120 Fortran instructions. By this proposed program, the following are obtained: 1) The total species concentration of hydrogen combustion, starting from the sum of initial reactants concentrations [H2] + [O2], gradually diminishes, due to termination reaction by wall destruction, and tends to the final concentration of the product [H2O], that is to the 2/3 of its initial value, in accordance to the established overall stoichiometric reaction of hydrogen combustion 2H2 + O2 → 2H2O. 2) Time-histories for concentrations of main species H2, O2, H, H2O of hydrogen combustion, in explosion and equilibrium regions, obtained by the proposed program, are compared to corresponding ones obtained by accurate computational studies of [3]. 3) In the first step of the algorithm, the only nonzero species concentrations are those of reactants [H2], [O2]. So, the maximum reaction rate is that of the forward initiation reaction max R = Rif = kif[H2] [O2], where the rate constant kif is very slow. Thus, the first time steplength Δt1 = 10-6mol·L-1/max R results long in sec. After the first step, the sequences of all the following Δt’s are very short, in μsec. So, the first time steplength Δt1 can be considered as ignition delay time. 4) It is assumed that explosion corresponds to ignition delay time Δt1 t1 = 10 sec., can be considered as explosion limit curve. This curve is compared to the corresponding one obtained by the accurate computational studies of [2].
基金The National Natural Science Fund(No.50975227)The National High-tech R & D Program("863"Program)(No.2011AA100507-04)
文摘In order to improve the design and research and development (R & D) efficiency of the pressure- compensating drip irrigation emitter,a step-by-step computational fluid dynamics (CFD) design method was proposed based on CFD theory combined with the finite element method. By analyzing its hydraulic performance through the step-by-step CFD method,the prediction pressure-flow curve(p-Q curve) of the pressure-compensating emitter was obtained. Then the test samples were fabricated using rapid prototype and manufacturing(RP & M) technology. The emitters' hydraulic performance experiment was carried out and the experimental p-Q curve was obtained. The step-by-step CFD design method was verified by comparing the experimental p-Q curve with the prediction values,which showed that the prediction values met the experimental results well within the normal range of the emitter's working pressure. On this basis,the effect of the emitter structure on its pressure-compensating performance was studied,which showed that the height of the pressure-compensating region had significant effects on the emitter's pressure-compensating performance. Series products of the pressure-compensating emitter could be designed by changing the region's height.
文摘Objective: Using the nursing methods in the title, to further explore the postoperative recovery of the fracture patients mentioned this time, in order to clarify the influence of nursing on them. Methods: Lumbar compression fracture is the main figure in this study, and the whole process is carried out around it. By implementing the nursing methods in the topic, the rehabilitation process is shortened. Results: After the rational application of the nursing methods in this study in clinic, the patients recovery has changed, with JOA and other excellent scores as the performance. The quality of life has been improved accordingly, and the patients impression of medical staff has been improved, so their dissatisfaction has gradually decreased. Conclusion: After the research, through the analysis of the results, it is suggested that the nursing methods used can have a positive impact on the postoperative rehabilitation of the key figures in this research.
基金supported by the National Natural Science Foundation of China(Nos.82060599 and 52003006)the Open Project of Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases,Ministry of Education(No.XN201911)+3 种基金the Natural Science Foundation of Jiangxi Province(No.20202BABL213018)the Science and Technology Project of the Education Department of Jiangxi Province(Nos.GJJ190795 and GJJ190827)the Research Fund of Gannan Medical University(Nos.QD201903,QD201912,ZD201901,YQ202003,and QD201825)Undergraduate Science and Technology Innovation Project of Gannan Medical University(No.BKSZR201903).
文摘Currently,chemotherapy is the main clinical therapy of tumors.Depressingly,most chemotherapeutic drugs such as doxorubicin and paclitaxel(PTX)have poor water solubility,leading to low bioavailability and serious side effects.Till now,although a variety of nanoparticulate drug delivery systems have been designed to ameliorate the above disadvantage of chemotherapy drugs,their application is still severely limited due to the complex preparation,poor stability,low drug loading,and premature drug release.Herein,a metal phenolic network-based drug delivery system with superior stability,satisfactory drug loading capacity,good biocompatibility,reduced undesired premature release,and excellent anti-tumor ability has been established for achieving step-by-step multiple stimuli-responsive drug delivery.Firstly,the redox-responsive dimeric paclitaxel(diPTX)prodrug was synthesized.Then diPTX@Fe&tannic acid(diPTX@Fe&TA)complex nanoparticles with satisfactory PTX loading capacity were obtained by deposition of Fe&TA network complex on the nanocore of diPTX rapidly with a simple method.The diPTX@Fe&TA nanoparticles have a hydrodynamic diameter of 152.6±1.2 nm,long-term colloidal stability,and high PTX loading content of 24.7%.Besides,diPTX@Fe&TA could expose to the acidic lysosomal environment and the reduction cytoplasmic environment continuously,resulting in the sequential release of diPTX and PTX when it was phagocytosed by tumor cells.Meanwhile,PTX showed almost no release under physiological condition(pH 7.4),which effectively inhibited the undesirable premature release of PTX.More importantly,diPTX@Fe&TA could suppress the growth of tumor effectively in vivo,along with negligible toxicity for organs.This work developed a simple and novel approach for the construction of a stepwise multiple stimuli-responsive drug delivery system with superior stability and satisfactory drug loading capacity to inhibit tumor growth effectively.
基金support from the 2023 Basic Research Foundation Project for Universities in the Inner Mongolia Autonomous Region(Grant No.2023RCTD006)the National Natural Science Foundation of China(Grant No.51864041,51664044).
文摘The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansion of strip samples was measured using a linear dilatometer during the staged reduction process at a temperature of 900℃.The existence states of MgO in hematite,magnetite,and wüstite were investigated through thermodynamic calculations.The magnetite strip samples were subjected to oxidizing roasting at 1250℃ for 30 min to produce hematite strip samples.The strip samples with 0.49,1.49,2.49,and 3.49 wt.%MgO were analyzed for length change.It was observed that the sample with 2.49 wt.%MgO exhibited the least significant length change.The lengths of the samples with the initial length being 20 mm before reduction changed during the reduction stages of Fe_(2)O_(3)→Fe_(3)O_(4),Fe_(3)O_(4)→FeO,and FeO→Fe were 615,−25,and−378μm,respectively.The volume expansion of hematite to magnetite was primarily attributed to the crystal transformation.During the reduction stage from wüstite to metallic iron,a substantial contraction occurred,while the slag phase was able to retain its original basic shape.The enclosed areas,as indicated by the expansion change curves of the samples with 0.49,1.49,2.49,and 3.49 wt.%MgO,were measured at 3.76×10^(6),3.23×10^(6),3.05×10^(6),and 3.17×10^(6)μm s,respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.12072105,11932006,and 52308498)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20220976).
文摘Dynamic wake field information is vital for the optimized design and control of wind farms.Combined with sparse measurement data from light detection and ranging(LiDAR),the physics-informed neural network(PINN)frameworks have recently been employed for forecasting freestream wind and wake fields.However,these PINN frameworks face challenges of low prediction accuracy and long training times.Therefore,this paper constructed a PINN framework for dynamic wake field prediction by integrating two accuracy improvement strategies and a step-by-step training time saving strategy.The results showed that the different performance improvement routes significantly improved the overall performance of the PINN.The accuracy and efficiency of the PINN with spatiotemporal improvement strategies were validated via LiDAR-measured data from a wind farm in Shandong province,China.This paper sheds light on load reduction,efficiency improvement,intelligent operation and maintenance of wind farms.
基金supported in part by the National Natural Science Foundation of China(61340041,61374079 and 61903126)the Natural Science Foundation of Henan Province(182300410112).
文摘As all generators are distributed in different areas among large scale power systems,the cooperative manipulation of the multi-generator system cannot operate well without consideration of the distance information of the generators.A distributed step-by-step finite-time consensus scheme for the heterogeneous battery energy storage system(BESS)is proposed in this paper,where the coordinated consensus can come into reality within a limited time,which is appealing for the electrical engineering community.To be concrete,at first,all BESSs are classified into several clusters according to their locations,and in each cluster,there is an active leader in charge of information receiving from outside.Then,in order to coordinate the multi BESSs,five inputs,which are function oriented,were used to achieve energy level balancing,active/reactive power sharing,and the consensus of voltage and frequency of the multi BESSs.Furthermore,the frequency and voltage restoration to the nominal values of the main grid were made possible by the introduction of a virtual leader,which is actually an external leader.Compared with the centralized methods,this control scheme is entirely distributed,and each BESS only utilizes the information of its own and its neighbors.In addition,this control is robust to the load perturbation and the plug-and-play of the communication topology.Finally,some simulation experiments are executed on the modified IEEE 57-bus system to verify the suggested scheme.
基金Project supported by the National Natural Science Foundation of China(No.61474080)the Program for New Century Excellent Talents in University,China
文摘We propose a pipelined Reed-Solomon(RS) decoder for an ultra-wideband system using a modified stepby-step algorithm. To reduce the complexity, the modified step-by-step algorithm merges two cases of the original algorithm. The pipelined structure allows the decoder to work at high rates with minimum delay. Consequently, for RS(23,17) codes, the proposed architecture requires 42.5% and 24.4% less area compared with a modified Euclidean architecture and a pipelined degree-computationless modified Euclidean architecture, respectively. The area of the proposed decoder is 11.3% less than that of the previous step-by-step decoder with a lower critical path delay.
文摘The primary aim of the study was to prepare narrow sized polymeric nanoparticles by implementing few modifications to the conventional nanoprecipitation technique and to evaluate the effect of various process parameters on prepared polymeric nanoparticles.Eudragit E 100 nanoparticles were prepared by modified nanoprecipitation technique and step-by-step optimization was carried out to evaluate the effect of various process parameters such as organic solvent,polymer concentration,percentage of organic solvent,mode of addition of organic solvent in to aqueous phase,volume of aqueous phase,poloxamer 188 concentration,β-cyclodextrin concentration,temperature generated during sonication process,sonication duration,and drug concentration on the particle size,surface area,distribution width and uniformity of the prepared nanoparticles.The optimized process parameters were implemented to fabricate dual drug loaded Eudragit E 100 nanoparticles which were spherical in shape with mean particle size in the range of 118 to 140 nm,polydispersity index in the range of 0.187 to 0.254 and zeta potential in the range of 16.6 to 28.8 mV.Thus developed modified nanoprecipitation method can be used to fabricate narrow sized polymeric nanoparticles.
文摘对码长n=2m-1纠两个错误的二进制BCH码,本文介绍了一种新的step by step译码算法。译码算法能直接确定接收的比特是否正确而不需要知道接收矢量的错误数目,也不需要知道相应的错误位置多项式。基于这种译码算法的译码器的优点在于占用硬件资源最少,实现简单快速。此外,这种译码方法特别适合于长码。
