Uniaxial compressive strength(UCS)is a significant mechanical measure in rock engineering,key for classifying rock masses,conducting stability assessments,and guiding design processes.Over the past five decades,numero...Uniaxial compressive strength(UCS)is a significant mechanical measure in rock engineering,key for classifying rock masses,conducting stability assessments,and guiding design processes.Over the past five decades,numerous techniques and devices have emerged for UCS measurement.This paper presents a comprehensive literature review of existing methodologies and advancements in UCS testing,examining the theoretical foundations,testing equipment,data processing techniques,and criteria for selecting appropriate UCS testing methods.Additionally,the study highlights a shift toward automated,precise,and computational approaches with multiple inputs(i.e.multiple regression,machine learning,ML)for UCS prediction.Approximately 221 articles published by various researchers between 2000 and 2024 related to ML were reviewed,focusing on the application of ML models,including artificial neural networks(ANNs),adaptive-network-based fuzzy inference system(ANFIS),random forest(RF),support vector machine(SVM),and extreme gradient boosting(XGBoost),in UCS prediction.The review also observed the growing use of hybrid models integrating ML with optimization techniques,significantly improving UCS estimation.Numerous empirical correlations,both direct and indirect,have been established in the past several years based on the physical properties of rocks.However,utilizing these proposed equations to reliably estimate UCS remains challenging due to the variability in lithology,rock origin,and other factors.This study systematically presents the established correlation expressions,considering their lithology,the number of samples used to establish the expressions,the coefficient of determination(R2),and the locations.This allows geologists and engineers to easily apply these established expressions in situations where direct estimation is not possible,enabling them to approximate UCS results.展开更多
Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observat...Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observation, tracer studies of determining exogenous inclusions from slag and lining erosion, SEN clogging and final prod- uct tests. There is no single ideal method of detecting and evaluating inclusions in steel, so it is better to use several methods simultaneously to give a more accurate evaluation. Total oxygen content and nitrogen pickup in low carbon aluminum-killed steel as criterion of clean steel in many plants are summarized.展开更多
Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility,biodegradability,and mechanical properties that are si...Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility,biodegradability,and mechanical properties that are similar to natural bone.However,direct in vitro assessment of these materials in the presence of cells is complicated by degradation products from the alloy that lead to a false positive for the most commonly used cell adhesion and cell proliferation assays.In this paper,a cyanine dye was used to quantitatively evaluate the in vitro biocompatibility of a Mg AZ31 alloy by both direct and indirect methods.The cytotoxicity of the corrosion products was evaluated via an indirect method;a 25%decrease in cell viability compared to control samples was observed.Moreover,direct assessment of cell adhesion and proliferation showed a statistically significant increase in cell number at the surface after 72 h.In addition,the degradation rate and surface characteristics of the Mg AZ31 alloy were evaluated for both direct and indirect tests.The degradation rate was unaffected by the presence of cells while evidence of an increase in calcium phosphate deposition on the magnesium alloy surface in the presence of cells was observed.This study demonstrates that a cyanine dye based assay provides a more accurate assessment of the overall in vitro biocompatibility of biodegradable metals than the more commonly used assays reported in the literature to date.展开更多
The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economic...The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economical, less time-consuming, and easily adaptable to the field. The main aim of this study was to derive correlations between direct and indirect test methods for basalt and rhyolite rock types from Carlin trend deposits in Nevada. In the destructive methods, point load index, block punch index, and splitting tensile strength tests are performed. In the non-destructive methods, Schmidt hammer and ultrasonic pulse velocity tests are performed. Correlations between the direct and indirect compression strength tests are developed using linear and nonlinear regression analysis methods. The results show that the splitting tensile strength has the best correlation with the uniaxial compression strength.Furthermore, the Poisson's ratio has no correlation with any of the direct and indirect test results.展开更多
Measurement of soil bulk density is important for understanding the physical, chemical, and biological properties of soil. Accurate and rapid soil bulk density measurement techniques play a significant role in agricul...Measurement of soil bulk density is important for understanding the physical, chemical, and biological properties of soil. Accurate and rapid soil bulk density measurement techniques play a significant role in agricultural experimental research. This review is a comprehensive summary of existing measurement methods and evaluates their advantages, disadvantages, potential sources of error,and directions for future development. These techniques can be broadly categorised as direct and indirect methods. Direct methods include core, clod, and excavation sampling, whereas indirect methods include the radiation and regression approaches. The core method is most widely used, but it is time consuming and difficult to use for sampling multiple soil depths. The size of the coring cylinder used, operator experience, sampling depth, and in-situ soil moisture content significantly affect its accuracy. The clod method is suitable for use with heavy clay soils, and its accuracy is dependent on equipment calibration, drying time, and operator experience, but the process is complicated and time consuming. Excavation techniques are most commonly used to evaluate the bulk density of forest soils, but have major limitations as they cannot be used in soils with large pores and their measurement accuracy is strongly influenced by soil texture and the type of analysis selected. The indirect methods appear to have greater accuracy than direct approaches, but have higher costs, are more complex, and require greater operator experience. One such approach uses gamma radiation, and its accuracy is strongly influenced by soil depth. Regression methods are economical as they can make indirect measurements, but these depend on good, quality data of soil texture and organic matter content and geographical and climatic properties. Also, like most of the other approaches, its accuracy decreases with sampling depth.展开更多
The wheel-rail force measurement is of great importance to the condition monitoring and safety evaluation of railway vehicles. In this paper, an improved indirect method for wheel-rail force measurement is proposed to...The wheel-rail force measurement is of great importance to the condition monitoring and safety evaluation of railway vehicles. In this paper, an improved indirect method for wheel-rail force measurement is proposed to evaluate the running safety of railway vehicles. In this method, the equilibrium equations of a suspended wheelset are derived and the wheel-rail forces are then be obtained from measured suspension and inertia forces. This indirect method avoids structural modifications to the wheelset and is applicable to the long-term operation of railway vehicles. As the wheel-rail lateral forces at two sides of the wheelset are difficult to separate, a new derailment criterion by combined use of wheelset derailment coefficient and wheel unloading ratio is proposed. To illustrate its effectiveness, the indirect method is applied to safety evaluation of rail- way vehicles in different scenarios, such as the cross wind safety of a high-speed train and the safety of a metro vehicle with hunting motions. Then, the feasibility of using this method to identify wheel-rail forces for low-floor light rail vehicles with resilient wheels is discussed. The values identified by this method is compared with that by Simpack simulation for the same low-floor vehicle, which shows a good coincidence between them in the time domain of the wheelset lateral force and the wheel-rail vertical force. In addition, use of the method to determine the high-frequency wheel-rail interaction forces reveals that it is possible to identify the high-frequency wheel-rail forces through the accelerations on the axle box.展开更多
To solve the receding horizon control （RHC） problem in an online manner, a novel numerical method called the indirect Radau pseudospectral method （IRPM） is proposed in this paper. Based on calculus of variations a...To solve the receding horizon control （RHC） problem in an online manner, a novel numerical method called the indirect Radau pseudospectral method （IRPM） is proposed in this paper. Based on calculus of variations and the first-order necessary optimality condition, the RHC problem for linear time-varying （LTV） system is transformed into the two-point boundary value problem （TPBVP）. The Radau pseudospectral approximation is employed to discretize the TPBVP into well-posed linear algebraic equations. The resulting linear algebraic equations are solved via a matrix partitioning approach afterwards to obtain the optimal feedback control law. For the nonlinear system, the linearization method or the quasi linearization method is employed to approximate the RHC problem with successive linear approximations. Subsequently, each linear problem is solved via the similar method which is used to solve the RHC problem for LTV system. Simulation results of three examples show that the IRPM is of high accuracy and of high compu- tation efficiency to solve the RHC problem and the stability of closed-loop systems is guaranteed.展开更多
This paper applies the singular integral operators,singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels,which are established in[1],to give a unifie...This paper applies the singular integral operators,singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels,which are established in[1],to give a unified framework for various collocation methods of numerical solutions of singular integral equations with Cauchy kernels.Under the framework,the coincidence of the direct quadrature method and the indirect quadrature method is very simple and obvious.展开更多
A novel control method for a general class of nonlinear systems using fuzzy logic systems （FLSs） is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a ...A novel control method for a general class of nonlinear systems using fuzzy logic systems （FLSs） is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.展开更多
This paper.fi＇rst conducts a systematic review of domestic and foreign scholars＇ approaches to predicting short-term capital flows, then employs a combination of both direct and indirect methods to carry out its ana...This paper.fi＇rst conducts a systematic review of domestic and foreign scholars＇ approaches to predicting short-term capital flows, then employs a combination of both direct and indirect methods to carry out its analysis. Three kinds of indicators, both specific and general, are applied in both methods. Thorough consideration is given to short-term international capital inflow from trade, other current account items, capital account, and errors and omissions, as well as other channels through which short term capital might accrue to a nation＇s balance. Based on a comprehensive comparison of year-on-year data, this paper also estimates monthly data using a simplified, indirect calculation approach. Estimates show that, despite a degree of difference in results between methods, most estimates are highly consistent for a given period. Based on monthly estimates, we conclude that turbulence in international financial markets （i.e., the United States subprime mortgage crisis and the European sovereign debt crisis） has had a major impact on China ＇s short-term capital flow.展开更多
The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combini...The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combining the Maxwell equation and phenomenological theory. Since the procedure is similar to indirect measurement of the EC effect, the results can serve as a reference for experiments. The results suggest that（i） it is reasonable to use zero-field CP,（ii） optimized ？T should be 2 K,（iii） it is better to keep △E 〈 EC, and（iv） E1〈 EC. Here, EC is the coercive field of material.展开更多
Nuclear reaction studies on unstable isotopes can strongly help in improving our understanding of nucleosynthesis in stars.Indirect approaches to determining astrophysical reaction rates are increasingly common-place ...Nuclear reaction studies on unstable isotopes can strongly help in improving our understanding of nucleosynthesis in stars.Indirect approaches to determining astrophysical reaction rates are increasingly common-place and undergoing continuous refinement.Of particular interest is the use of such indirect techniques at storage rings,which,among other aspects,allow to recycle rare unstable beams.We propose to investigate the reaction rates of astrophysical interest using indirect methods(surrogate,Trojan horse,etc.)in reverse kinematics at the IMP-CAS storage ring.Long lived radioactive ion beams,produced remotely,can be accelerated,and made to interact with light targets.The proposed reactions are^(85)Kr(p,p’γ),^(85)Kr(d,pγ),constraining the neutron flux in an s-process branching point,^(79)Se(p,p’γ),^(79)Se(d,pγ),constraining the temperature in s-process nucleosyntheses,and^(59)Fe(d,pγ),constraining core collapse supernovae.展开更多
[Objective] This study aimed to investigate the secretory expression of P97R1 gene of Mycoplasma hyopneumoniae（Mhp） in Pichia pastoris expression system and the primary application; of the expression product. [Metho...[Objective] This study aimed to investigate the secretory expression of P97R1 gene of Mycoplasma hyopneumoniae（Mhp） in Pichia pastoris expression system and the primary application; of the expression product. [Method] A pair of specific primers was designed to conduct PCR according to the Mhp P97R1 gene sequence in Genbank, and the amplified P97R1 gene was cloned into the pPICZa-A yeast expression vector to construct the secretory recombinant expression vector pPICZa-A-P97R1. The plasmid pPICZa-A-p97R1 linearized by Sac I was transformed into P. pastoris GSl15 by electroporation. Positive transformant identified by PCR was incubated to express P97R1 protein after methanol induction. And the expression product was identified using SDS-PAGE and Western-blotting anal.wsis. [Result] P97R1 protein was successfully expressed in the P. pastoris system, with a secre- tory amount of 499μg/ml, and revealed good reactogenicity. Meanwhile, an indirect ELISA method was established with P97R1 protein after the optimization of each reaction factor, which showed good specificity and repeatability according to repeated tests. [Conclusion] This study provides bases for developing the ELISA Kit for anti- body detection and genetically engineered vaccine to Mhp.展开更多
In psychology,the concept of interpretation has been namely associated to the subjectivist paradigm underpinning qualitative approaches,rather than the objectivist paradigm charactefising quantitative research.In this...In psychology,the concept of interpretation has been namely associated to the subjectivist paradigm underpinning qualitative approaches,rather than the objectivist paradigm charactefising quantitative research.In this article,we challenge this belief by showing how interpretation concerns psychology as a whole.To do this,the authors will first consider some dominant tendencies characterising the psychological field in general,such as the"empiricist illusion"and the"trap of scientism"(Vygotsky 1999).Moreover,they will introduce the cultural perspective in psychology,pertinent to deconstruct several assumptions regarding research within the discipline.Stemming from this approach,"indirect methods"will be presented with regard to their potential to analyse psychological phenomena both qualitatively and scientifically.They will conclude by describing a set of principles that can be implemented when doing qualitative research as to ensure the quality and the adequacy of interpretation.展开更多
Due to rapid demographic growth, economic and technological changes, urban environments are highly exposed to the impacts of climate change and environmental catastrophes. Despite the pressure to which urban forests a...Due to rapid demographic growth, economic and technological changes, urban environments are highly exposed to the impacts of climate change and environmental catastrophes. Despite the pressure to which urban forests are exposed, they still play important roles through the service they provide: air quality, shade, and reduction of dioxide of carbon. The present study was carried out in the city of Yaoundé, Cameroon, especially in one of its suburb areas, Elig-Effa West, a neighborhood with spontaneous settlements. The study aimed at assessing the plant species diversity, and carbon sequestration potentials of diverse trees recorded using indirect methods. Six sampling plots of 100 × 100 m were established in the study area. Our results recorded a total of 16 species grouped into 12 families. Apocynaceae, Mimosaceae and Moraceae were the most represented families. The most represented species throughout the sampling plots were Mangifera indica, Persea americana, Annona muricata and Psidium gaujava, which are all fruiting trees. Carbon stock for the study area was estimated at 16.08 ± 5.60 tC with an average of 0.23 ± 0.08 tC/ha. The results also showed the species to be considered in a potential restoration program should be first fruiting trees, followed by non-fruiting trees useful to population, especially those that have their trunk peeled, a sign that they are used by the population. Nevertheless, informal settlements contribute to carbon sequestration, that well targeted urban reforestation will substantially improve.展开更多
This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the d...This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the displacements and stresses on the boundary of the canyon where fictitious uniform moving loads are applied to calculate the Green＇s fi.mctions for the displacements and stresses. The amplitudes of the loads are determined by the boundary conditions. The free field displacements are added to the fictitious uniform moving loads induced displacements and the total response is obtained. Numerical calculations are performed for a canyon with homogenous and in one layer over bedrock. The effects of the thickness and stiffness of the layer on the amplification are studied and discussed.展开更多
Traditionally,numerical trajectory integration for shooting equation calculation and iterations for shooting with randomly guessed initial solutions deteriorate the real-time performance of indirect methods for on-boa...Traditionally,numerical trajectory integration for shooting equation calculation and iterations for shooting with randomly guessed initial solutions deteriorate the real-time performance of indirect methods for on-board applications.In this study,the indirect method is improved to achieve real-time trajectory optimization of fuel-optimal powered planetary landings with the help of analytical shooting equation derivations and a practical homotopy technique.Specifically,the contributions of this paper are threefold.First,the analytical expressions for shooting equation calculation are derived to replace the traditional time-consuming trajectory integration.Consequently,the computational efficiency is significantly improved.Second,the original three-dimensional landing problem is connected with a simplified one-dimensional problem that only involves the vertical dynamics,and its analytical solution is obtained based on Pontryagin’s minimum principle.Third,starting with the analytical solution,the accurate solution of the original landing problem can be obtained through an adaptive homotopy process.Simulation results of Earth landing scenarios are given to substantiate the effectiveness of the proposed techniques and illustrate that the developed method can obtain a fuel-optimal landing trajectory in 5 ms with 100%success rate.展开更多
Abstract： The scattering of plane SH-waves by topographic features in a layered transversely isotropic （TI） half-space is investigated by using an indirect boundary element method （IBEM）. Firstly, the anti-plane ...Abstract： The scattering of plane SH-waves by topographic features in a layered transversely isotropic （TI） half-space is investigated by using an indirect boundary element method （IBEM）. Firstly, the anti-plane dynamic stiffness matrix of the layered TI half-space is established and the free fields are solved by using the direct stiffness method. Then, Green＇s functions are derived for uniformly distributed loads acting on an inclined line in a layered TI half-space and the scattered fields are constructed with the deduced Green＇s functions. Finally, the free fields are added to the scattered ones to obtain the global dynamic responses. The method is verified by comparing results with the published isotropic ones. Both the steady-state and transient dynamic responses are evaluated and discussed. Numerical results in the frequency domain show that surface motions for the TI media can be significantly different from those for the isotropic case, which are strongly dependent on the anisotropy property, incident angle and incident frequency. Results in the time domain show that the material anisotropy has important effects on the maximum duration and maximum amplitudes of the time histories.展开更多
The dynamic soil-tunnel interaction is studied by indirect boundary element method （IBEM）, using the model of a rigid tunnel in layered half-space, which is simplified to a single soil layer on elastic bedrock, subj...The dynamic soil-tunnel interaction is studied by indirect boundary element method （IBEM）, using the model of a rigid tunnel in layered half-space, which is simplified to a single soil layer on elastic bedrock, subjected to incident plane SH waves. The accuracy of the results is verified through comparison with the analytical solution. It is shown that soil-tunnel interaction in layered half-space is larger than that in homogeneous half-space and this interaction mechanism is essentially different from that of soil-foundation-superstructure interaction.展开更多
The indirect boundary element method （IBEM） is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space. According to the theory of single-layer potential, the scattered-wave fiel...The indirect boundary element method （IBEM） is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space. According to the theory of single-layer potential, the scattered-wave field can be constructed by applying virtual uniform loads on the surface of lined tunnel and the nearby wedge surface. The densities of virtual loads can be solved by establishing equations through the continuity conditions on the interface and zero-traction conditions on free surfaces. The total wave field is obtained by the superposition of free field and scattered-wave field in elastic wedge space. Numerical results indicate that the IBEM can solve the diffraction of elastic wave in elastic wedge space accurately and effi- ciently. The wave motion feature strongly depends on the wedge angle, the angle of incidence, incident frequency, the location of lined tunnel, and material parameters. The waves interference and amplification effect around the tunnel in wedge space is more significant, causing the dynamic stress concentration factor on rigid tunnel and the displacement amplitude of flexible tunnel up to 50.0 and 17.0, respectively, more than double that of the case of half-space. Hence, considerable attention should be paid to seismic resistant or anti-explosion design of the tunnel built on a slope or hillside.展开更多
文摘Uniaxial compressive strength(UCS)is a significant mechanical measure in rock engineering,key for classifying rock masses,conducting stability assessments,and guiding design processes.Over the past five decades,numerous techniques and devices have emerged for UCS measurement.This paper presents a comprehensive literature review of existing methodologies and advancements in UCS testing,examining the theoretical foundations,testing equipment,data processing techniques,and criteria for selecting appropriate UCS testing methods.Additionally,the study highlights a shift toward automated,precise,and computational approaches with multiple inputs(i.e.multiple regression,machine learning,ML)for UCS prediction.Approximately 221 articles published by various researchers between 2000 and 2024 related to ML were reviewed,focusing on the application of ML models,including artificial neural networks(ANNs),adaptive-network-based fuzzy inference system(ANFIS),random forest(RF),support vector machine(SVM),and extreme gradient boosting(XGBoost),in UCS prediction.The review also observed the growing use of hybrid models integrating ML with optimization techniques,significantly improving UCS estimation.Numerous empirical correlations,both direct and indirect,have been established in the past several years based on the physical properties of rocks.However,utilizing these proposed equations to reliably estimate UCS remains challenging due to the variability in lithology,rock origin,and other factors.This study systematically presents the established correlation expressions,considering their lithology,the number of samples used to establish the expressions,the coefficient of determination(R2),and the locations.This allows geologists and engineers to easily apply these established expressions in situations where direct estimation is not possible,enabling them to approximate UCS results.
文摘Indirect methods to detect and evaluate inclusions in steel are extensively reviewed, which include total oxygen content measurement, nitrogen pickup, steel and slag composition measurement, lining refractory observation, tracer studies of determining exogenous inclusions from slag and lining erosion, SEN clogging and final prod- uct tests. There is no single ideal method of detecting and evaluating inclusions in steel, so it is better to use several methods simultaneously to give a more accurate evaluation. Total oxygen content and nitrogen pickup in low carbon aluminum-killed steel as criterion of clean steel in many plants are summarized.
基金We gratefully acknowledge the Ministry of Education in the Kingdom of Saudi Arabia for financial support.
文摘Magnesium and its alloys are promising candidates for a new generation of biodegradable metals in orthopaedic applications due to their excellent biocompatibility,biodegradability,and mechanical properties that are similar to natural bone.However,direct in vitro assessment of these materials in the presence of cells is complicated by degradation products from the alloy that lead to a false positive for the most commonly used cell adhesion and cell proliferation assays.In this paper,a cyanine dye was used to quantitatively evaluate the in vitro biocompatibility of a Mg AZ31 alloy by both direct and indirect methods.The cytotoxicity of the corrosion products was evaluated via an indirect method;a 25%decrease in cell viability compared to control samples was observed.Moreover,direct assessment of cell adhesion and proliferation showed a statistically significant increase in cell number at the surface after 72 h.In addition,the degradation rate and surface characteristics of the Mg AZ31 alloy were evaluated for both direct and indirect tests.The degradation rate was unaffected by the presence of cells while evidence of an increase in calcium phosphate deposition on the magnesium alloy surface in the presence of cells was observed.This study demonstrates that a cyanine dye based assay provides a more accurate assessment of the overall in vitro biocompatibility of biodegradable metals than the more commonly used assays reported in the literature to date.
基金CDC/NIOSH for their partial funding of this work
文摘The difficulties associated with performing direct compression strength tests on rocks lead to the development of indirect test methods for the rock strength assessment. Indirect test methods are simple, more economical, less time-consuming, and easily adaptable to the field. The main aim of this study was to derive correlations between direct and indirect test methods for basalt and rhyolite rock types from Carlin trend deposits in Nevada. In the destructive methods, point load index, block punch index, and splitting tensile strength tests are performed. In the non-destructive methods, Schmidt hammer and ultrasonic pulse velocity tests are performed. Correlations between the direct and indirect compression strength tests are developed using linear and nonlinear regression analysis methods. The results show that the splitting tensile strength has the best correlation with the uniaxial compression strength.Furthermore, the Poisson's ratio has no correlation with any of the direct and indirect test results.
基金the Government and Ministry of Higher Education and Scientific Research, Iraq, for providing funding for this study as a scholarship for Ph.D. student for the first author Ahmed Abed Gatea Al-Shammary
文摘Measurement of soil bulk density is important for understanding the physical, chemical, and biological properties of soil. Accurate and rapid soil bulk density measurement techniques play a significant role in agricultural experimental research. This review is a comprehensive summary of existing measurement methods and evaluates their advantages, disadvantages, potential sources of error,and directions for future development. These techniques can be broadly categorised as direct and indirect methods. Direct methods include core, clod, and excavation sampling, whereas indirect methods include the radiation and regression approaches. The core method is most widely used, but it is time consuming and difficult to use for sampling multiple soil depths. The size of the coring cylinder used, operator experience, sampling depth, and in-situ soil moisture content significantly affect its accuracy. The clod method is suitable for use with heavy clay soils, and its accuracy is dependent on equipment calibration, drying time, and operator experience, but the process is complicated and time consuming. Excavation techniques are most commonly used to evaluate the bulk density of forest soils, but have major limitations as they cannot be used in soils with large pores and their measurement accuracy is strongly influenced by soil texture and the type of analysis selected. The indirect methods appear to have greater accuracy than direct approaches, but have higher costs, are more complex, and require greater operator experience. One such approach uses gamma radiation, and its accuracy is strongly influenced by soil depth. Regression methods are economical as they can make indirect measurements, but these depend on good, quality data of soil texture and organic matter content and geographical and climatic properties. Also, like most of the other approaches, its accuracy decreases with sampling depth.
基金supported by the National Natural Science Foundation of China (Grant No. U1334206 and No. 51475388)Science & Technology Development Project of China Railway Corporation (Grant No. J012-C)
文摘The wheel-rail force measurement is of great importance to the condition monitoring and safety evaluation of railway vehicles. In this paper, an improved indirect method for wheel-rail force measurement is proposed to evaluate the running safety of railway vehicles. In this method, the equilibrium equations of a suspended wheelset are derived and the wheel-rail forces are then be obtained from measured suspension and inertia forces. This indirect method avoids structural modifications to the wheelset and is applicable to the long-term operation of railway vehicles. As the wheel-rail lateral forces at two sides of the wheelset are difficult to separate, a new derailment criterion by combined use of wheelset derailment coefficient and wheel unloading ratio is proposed. To illustrate its effectiveness, the indirect method is applied to safety evaluation of rail- way vehicles in different scenarios, such as the cross wind safety of a high-speed train and the safety of a metro vehicle with hunting motions. Then, the feasibility of using this method to identify wheel-rail forces for low-floor light rail vehicles with resilient wheels is discussed. The values identified by this method is compared with that by Simpack simulation for the same low-floor vehicle, which shows a good coincidence between them in the time domain of the wheelset lateral force and the wheel-rail vertical force. In addition, use of the method to determine the high-frequency wheel-rail interaction forces reveals that it is possible to identify the high-frequency wheel-rail forces through the accelerations on the axle box.
基金supported by the National Natural Science Foundation of China(Nos.61174221 and 61402039)
文摘To solve the receding horizon control （RHC） problem in an online manner, a novel numerical method called the indirect Radau pseudospectral method （IRPM） is proposed in this paper. Based on calculus of variations and the first-order necessary optimality condition, the RHC problem for linear time-varying （LTV） system is transformed into the two-point boundary value problem （TPBVP）. The Radau pseudospectral approximation is employed to discretize the TPBVP into well-posed linear algebraic equations. The resulting linear algebraic equations are solved via a matrix partitioning approach afterwards to obtain the optimal feedback control law. For the nonlinear system, the linearization method or the quasi linearization method is employed to approximate the RHC problem with successive linear approximations. Subsequently, each linear problem is solved via the similar method which is used to solve the RHC problem for LTV system. Simulation results of three examples show that the IRPM is of high accuracy and of high compu- tation efficiency to solve the RHC problem and the stability of closed-loop systems is guaranteed.
基金Supported by NNSF of China,SF of SEC of China and SF of Wuhan University.
文摘This paper applies the singular integral operators,singular quadrature operators and discretization matrices associated with singular integral equations with Cauchy kernels,which are established in[1],to give a unified framework for various collocation methods of numerical solutions of singular integral equations with Cauchy kernels.Under the framework,the coincidence of the direct quadrature method and the indirect quadrature method is very simple and obvious.
基金This project was supported by the National Natural Science Foundation of China (90405011).
文摘A novel control method for a general class of nonlinear systems using fuzzy logic systems （FLSs） is presertted. Indirect and direct methods are combined to design the adaptive fuzzy output feedback controller and a high-gain observer is used to estimate the derivatives of the system output. The closed-loop system is proven to be semiglobally uniformly ultimately bounded. In addition, it is shown that if the approximation accuracy of the fuzzy logic system is high enough and the observer gain is chosen sufficiently large, an arbitrarily small tracking error can be achieved. Simulation results verify the effectiveness of the newly designed scheme and the theoretical discussion.
文摘This paper.fi＇rst conducts a systematic review of domestic and foreign scholars＇ approaches to predicting short-term capital flows, then employs a combination of both direct and indirect methods to carry out its analysis. Three kinds of indicators, both specific and general, are applied in both methods. Thorough consideration is given to short-term international capital inflow from trade, other current account items, capital account, and errors and omissions, as well as other channels through which short term capital might accrue to a nation＇s balance. Based on a comprehensive comparison of year-on-year data, this paper also estimates monthly data using a simplified, indirect calculation approach. Estimates show that, despite a degree of difference in results between methods, most estimates are highly consistent for a given period. Based on monthly estimates, we conclude that turbulence in international financial markets （i.e., the United States subprime mortgage crisis and the European sovereign debt crisis） has had a major impact on China ＇s short-term capital flow.
基金Project supported by the Natural Science Foundation of Shanghai,China(Grant No.17ZR1447200)
文摘The influences of specific heat capacity CP, temperature step ？T, electric field step ？E, and initial electric field E1 on predicted electrocaloric（EC） temperature ？T of monodomain Ba TiO3 are examined by combining the Maxwell equation and phenomenological theory. Since the procedure is similar to indirect measurement of the EC effect, the results can serve as a reference for experiments. The results suggest that（i） it is reasonable to use zero-field CP,（ii） optimized ？T should be 2 K,（iii） it is better to keep △E 〈 EC, and（iv） E1〈 EC. Here, EC is the coercive field of material.
文摘Nuclear reaction studies on unstable isotopes can strongly help in improving our understanding of nucleosynthesis in stars.Indirect approaches to determining astrophysical reaction rates are increasingly common-place and undergoing continuous refinement.Of particular interest is the use of such indirect techniques at storage rings,which,among other aspects,allow to recycle rare unstable beams.We propose to investigate the reaction rates of astrophysical interest using indirect methods(surrogate,Trojan horse,etc.)in reverse kinematics at the IMP-CAS storage ring.Long lived radioactive ion beams,produced remotely,can be accelerated,and made to interact with light targets.The proposed reactions are^(85)Kr(p,p’γ),^(85)Kr(d,pγ),constraining the neutron flux in an s-process branching point,^(79)Se(p,p’γ),^(79)Se(d,pγ),constraining the temperature in s-process nucleosyntheses,and^(59)Fe(d,pγ),constraining core collapse supernovae.
基金Supported by the National Natural Science Foundation of China(31100136)the Special Fund for Independent Innovation of Agricultural Science and Technology in Jiangsu Province[CX(12)5051]~~
文摘[Objective] This study aimed to investigate the secretory expression of P97R1 gene of Mycoplasma hyopneumoniae（Mhp） in Pichia pastoris expression system and the primary application; of the expression product. [Method] A pair of specific primers was designed to conduct PCR according to the Mhp P97R1 gene sequence in Genbank, and the amplified P97R1 gene was cloned into the pPICZa-A yeast expression vector to construct the secretory recombinant expression vector pPICZa-A-P97R1. The plasmid pPICZa-A-p97R1 linearized by Sac I was transformed into P. pastoris GSl15 by electroporation. Positive transformant identified by PCR was incubated to express P97R1 protein after methanol induction. And the expression product was identified using SDS-PAGE and Western-blotting anal.wsis. [Result] P97R1 protein was successfully expressed in the P. pastoris system, with a secre- tory amount of 499μg/ml, and revealed good reactogenicity. Meanwhile, an indirect ELISA method was established with P97R1 protein after the optimization of each reaction factor, which showed good specificity and repeatability according to repeated tests. [Conclusion] This study provides bases for developing the ELISA Kit for anti- body detection and genetically engineered vaccine to Mhp.
文摘In psychology,the concept of interpretation has been namely associated to the subjectivist paradigm underpinning qualitative approaches,rather than the objectivist paradigm charactefising quantitative research.In this article,we challenge this belief by showing how interpretation concerns psychology as a whole.To do this,the authors will first consider some dominant tendencies characterising the psychological field in general,such as the"empiricist illusion"and the"trap of scientism"(Vygotsky 1999).Moreover,they will introduce the cultural perspective in psychology,pertinent to deconstruct several assumptions regarding research within the discipline.Stemming from this approach,"indirect methods"will be presented with regard to their potential to analyse psychological phenomena both qualitatively and scientifically.They will conclude by describing a set of principles that can be implemented when doing qualitative research as to ensure the quality and the adequacy of interpretation.
文摘Due to rapid demographic growth, economic and technological changes, urban environments are highly exposed to the impacts of climate change and environmental catastrophes. Despite the pressure to which urban forests are exposed, they still play important roles through the service they provide: air quality, shade, and reduction of dioxide of carbon. The present study was carried out in the city of Yaoundé, Cameroon, especially in one of its suburb areas, Elig-Effa West, a neighborhood with spontaneous settlements. The study aimed at assessing the plant species diversity, and carbon sequestration potentials of diverse trees recorded using indirect methods. Six sampling plots of 100 × 100 m were established in the study area. Our results recorded a total of 16 species grouped into 12 families. Apocynaceae, Mimosaceae and Moraceae were the most represented families. The most represented species throughout the sampling plots were Mangifera indica, Persea americana, Annona muricata and Psidium gaujava, which are all fruiting trees. Carbon stock for the study area was estimated at 16.08 ± 5.60 tC with an average of 0.23 ± 0.08 tC/ha. The results also showed the species to be considered in a potential restoration program should be first fruiting trees, followed by non-fruiting trees useful to population, especially those that have their trunk peeled, a sign that they are used by the population. Nevertheless, informal settlements contribute to carbon sequestration, that well targeted urban reforestation will substantially improve.
基金National Natural Science Foundation of China Under Grant No.50908156 and 50978183Tianjin Natural Science Foundation Under Grant No. 07JCZDJC10100
文摘This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the displacements and stresses on the boundary of the canyon where fictitious uniform moving loads are applied to calculate the Green＇s fi.mctions for the displacements and stresses. The amplitudes of the loads are determined by the boundary conditions. The free field displacements are added to the fictitious uniform moving loads induced displacements and the total response is obtained. Numerical calculations are performed for a canyon with homogenous and in one layer over bedrock. The effects of the thickness and stiffness of the layer on the amplification are studied and discussed.
基金supported by the National Natural Science Foundation of China(Nos.11872223,11902174,11772167)。
文摘Traditionally,numerical trajectory integration for shooting equation calculation and iterations for shooting with randomly guessed initial solutions deteriorate the real-time performance of indirect methods for on-board applications.In this study,the indirect method is improved to achieve real-time trajectory optimization of fuel-optimal powered planetary landings with the help of analytical shooting equation derivations and a practical homotopy technique.Specifically,the contributions of this paper are threefold.First,the analytical expressions for shooting equation calculation are derived to replace the traditional time-consuming trajectory integration.Consequently,the computational efficiency is significantly improved.Second,the original three-dimensional landing problem is connected with a simplified one-dimensional problem that only involves the vertical dynamics,and its analytical solution is obtained based on Pontryagin’s minimum principle.Third,starting with the analytical solution,the accurate solution of the original landing problem can be obtained through an adaptive homotopy process.Simulation results of Earth landing scenarios are given to substantiate the effectiveness of the proposed techniques and illustrate that the developed method can obtain a fuel-optimal landing trajectory in 5 ms with 100%success rate.
基金National Natural Science Foundation of China under Grant Nos.51578373 and 51578372
文摘Abstract： The scattering of plane SH-waves by topographic features in a layered transversely isotropic （TI） half-space is investigated by using an indirect boundary element method （IBEM）. Firstly, the anti-plane dynamic stiffness matrix of the layered TI half-space is established and the free fields are solved by using the direct stiffness method. Then, Green＇s functions are derived for uniformly distributed loads acting on an inclined line in a layered TI half-space and the scattered fields are constructed with the deduced Green＇s functions. Finally, the free fields are added to the scattered ones to obtain the global dynamic responses. The method is verified by comparing results with the published isotropic ones. Both the steady-state and transient dynamic responses are evaluated and discussed. Numerical results in the frequency domain show that surface motions for the TI media can be significantly different from those for the isotropic case, which are strongly dependent on the anisotropy property, incident angle and incident frequency. Results in the time domain show that the material anisotropy has important effects on the maximum duration and maximum amplitudes of the time histories.
基金National Natural Science Foundation of China under Grant 51378384Key Project of Natural Science Foundation of Tianjin Municipality under Grant 12JCZDJC29000
文摘The dynamic soil-tunnel interaction is studied by indirect boundary element method （IBEM）, using the model of a rigid tunnel in layered half-space, which is simplified to a single soil layer on elastic bedrock, subjected to incident plane SH waves. The accuracy of the results is verified through comparison with the analytical solution. It is shown that soil-tunnel interaction in layered half-space is larger than that in homogeneous half-space and this interaction mechanism is essentially different from that of soil-foundation-superstructure interaction.
基金National Natural Science Foundation of China under Grants (51278327)the Tianjin Research Program of Application Foundation and Advanced Technology (14JCYBJC21900)
文摘The indirect boundary element method （IBEM） is developed to solve the scattering of plane SH-waves by a lined tunnel in elastic wedge space. According to the theory of single-layer potential, the scattered-wave field can be constructed by applying virtual uniform loads on the surface of lined tunnel and the nearby wedge surface. The densities of virtual loads can be solved by establishing equations through the continuity conditions on the interface and zero-traction conditions on free surfaces. The total wave field is obtained by the superposition of free field and scattered-wave field in elastic wedge space. Numerical results indicate that the IBEM can solve the diffraction of elastic wave in elastic wedge space accurately and effi- ciently. The wave motion feature strongly depends on the wedge angle, the angle of incidence, incident frequency, the location of lined tunnel, and material parameters. The waves interference and amplification effect around the tunnel in wedge space is more significant, causing the dynamic stress concentration factor on rigid tunnel and the displacement amplitude of flexible tunnel up to 50.0 and 17.0, respectively, more than double that of the case of half-space. Hence, considerable attention should be paid to seismic resistant or anti-explosion design of the tunnel built on a slope or hillside.
