The proportionate recursive least squares(PRLS)algorithm has shown faster convergence and better performance than both proportionate updating(PU)mechanism based least mean squares(LMS)algorithms and RLS algorithms wit...The proportionate recursive least squares(PRLS)algorithm has shown faster convergence and better performance than both proportionate updating(PU)mechanism based least mean squares(LMS)algorithms and RLS algorithms with a sparse regularization term.In this paper,we propose a variable forgetting factor(VFF)PRLS algorithm with a sparse penalty,e.g.,l_(1)-norm,for sparse identification.To reduce the computation complexity of the proposed algorithm,a fast implementation method based on dichotomous coordinate descent(DCD)algorithm is also derived.Simulation results indicate superior performance of the proposed algorithm.展开更多
Land surface evapotranspiration(ET)is a critical component in the hydrological cycle but has not well been understood in data-scarce areas especially in river basins,like Nujiang River(NRB)which is characterized by la...Land surface evapotranspiration(ET)is a critical component in the hydrological cycle but has not well been understood in data-scarce areas especially in river basins,like Nujiang River(NRB)which is characterized by large elevation gradient and different vegetation zones with complex processes of water and energy exchange.The quality of ET from optical remote sensing is constrained by cloud cover which is common in the NRB in the monsoon seasons.To understand factors controlling the spatial-temporal heterogeneity of ET in NRB,we employed the Variable Infiltration Capacity(VIC)hydrological model by parameter optimization with support of quality controlled remote sensing ET product and observed river runoff series in the river.The modeled ET has increased during 1984-2018,which might be one of the reasons for the runoff decrease but precipitation increase in the same period.ET increase and runoff decrease tended to be quicker within altitudinal band of 2000-4000 m than in other areas in NRB.We observed that ET variation in different climatic zones were controlled by different factors.ET is generally positively correlated with precipitation,temperature,and shortwave radiation but negatively with relative humidity.In the Tundra Climate(Et)zone in the upper reach of NRB,ET is controlled by precipitation,while it is controlled by shortwave radiation in the snow climate with dry winter(Dw)zone.ET increase is influenced by the increase of temperature,wind speed,and shortwave radiation in the middle and downstream of NRB with warm temperate climate,fully humid(Cf)and warm temperate climate with dry winter(Cw).展开更多
Variability in soil properties is a critical element across wide areas of researches especially in several aspects of agriculture and environment including sewage disposal and global climate change. Particle size frac...Variability in soil properties is a critical element across wide areas of researches especially in several aspects of agriculture and environment including sewage disposal and global climate change. Particle size fraction (sand, silt, and clay), effective cation exchange capacity, base saturation, pH, organic carbon, total nitrogen, carbon nitrogen ratio, available phosphorus, exchangeable bases (calcium, magnesium, sodium, potassium) and acidity are frequently used in agriculture for soil management. The objective of this study therefore was to identify soil management factors from these set of 15 soil properties and spatial distribution of representative soil management properties. The study was carried out in the University of Uyo Teaching and Research Farm measuring 8.19 hectares in University of Uyo Annex, Uyo in Akwa Ibom State of Nigeria. Nine and ten traverses were made horizontally and vertically respectively at 40 meters intervals. A total of 58 soil samples were collected at 0 - 15 cm depth on the grid nodes of the traverses. Particle size distributions, exchangeable bases and acidity, effective cation exchange capacity (ECEC), available phosphorus (avail. P), base saturation (BS), organic carbon, total nitrogen, carbon nitrogen ratio (CNR) and pH of the samples were determined in the laboratory. Coefficient of variation indicated that 26.6% of the soil properties (sand content, pH, CNR and sodium) were least variable, 40.1% comprising silt, clay contents, ECEC, base saturation, phosphorus and magnesium were moderately. Whereas 33.3% of the soil properties comprising clay content, organic carbon, total nitrogen, exchangeable Ca, K and acidity (i.e.) were highly variable. There were significant correlation (p < 0.05) in 26.6% of the soil properties, the strongest negative significant (p < 0.01) correlations were between sand and clay (r = –0.85), exchangeable acidity and base saturation (r = –0.85), whereas the strongest positive significant correlations were between ECEC and Ca (r = 0.80), Ca and BS (r = 0.74), organic carbon and total nitrogen (r = 0.80). Principal component analysis indicated the existence of six factors including mineralogical or weathering, soil organic matter, cation exchange activity, soil texture, and dispersion and soil phosphorus based on either management or pedological considerations. Semivariance statistics showed that sand and clay contents, ECEC, BS and total N were moderately (≥25.7% ≤47.3%), while silt content, pH, organic carbon, CNR, avail. P, exchangeable Ca, Mg, Na and acidity (≥0.18% ≤22.8%) were strongly spatially dependent. The variability observed was primarily incident upon factors of soil formation. Therefore, the utilization of spatial structure of organic matter and texture factors in the management of nutrient and soil water will facilitate planning of crop production scheme on coastal plain sands soils.展开更多
For a century, hypothesis of a variable time is laid down by the Relativity Theory. This hypothesis can explain many Nature observations, experiments and formulas, for example the Lorentz factor demonstration. Because...For a century, hypothesis of a variable time is laid down by the Relativity Theory. This hypothesis can explain many Nature observations, experiments and formulas, for example the Lorentz factor demonstration. Because of such good explanations, the hypothesis of a variable time has been validated. Nevertheless, it remains some paradoxes and some predictions which are difficult to measure, as a reversible time or the time variation itself. The purpose of this article is to study another hypothesis. If it gives interesting results, it would mean that this alternative hypothesis can also be validated. The idea in this paper is to replace the variable time by a variable inertial mass. To the difference with the Theory of Relativity (where the inertial mass and the gravitational mass are equal and variable), the gravitational mass is here supposed to be constant. So, starting from the definition of the kinetic energy, it is introduced the Lorentz factor. And then it is demonstrated the value of the Lorentz factor thanks to a variable inertial mass. This variable inertial mass can also explain experiments, like Bertozzi experiment. If this alternative demonstration was validated, it could help to open doors, other physical effects could be explained like the addition of velocities.展开更多
Artificial bee colony(ABC) is one of the most popular swarm intelligence optimization algorithms which have been widely used in numerical optimization and engineering applications. However, there are still deficiencie...Artificial bee colony(ABC) is one of the most popular swarm intelligence optimization algorithms which have been widely used in numerical optimization and engineering applications. However, there are still deficiencies in ABC regarding its local search ability and global search efficiency. Aiming at these deficiencies,an ABC variant named hybrid ABC(HABC) algorithm is proposed.Firstly, the variable neighborhood search factor is added to the solution search equation, which can enhance the local search ability and increase the population diversity. Secondly, inspired by the neuroscience investigation of real honeybees, the memory mechanism is put forward, which assumes the artificial bees can remember their past successful experiences and further guide the subsequent foraging behavior. The proposed memory mechanism is used to improve the global search efficiency. Finally, the results of comparison on a set of ten benchmark functions demonstrate the superiority of HABC.展开更多
This paper discusses the utilization of latent variable modeling related to occupational health and safety in the mining industry.Latent variable modeling,which is a statistical model that relates observable and laten...This paper discusses the utilization of latent variable modeling related to occupational health and safety in the mining industry.Latent variable modeling,which is a statistical model that relates observable and latent variables,could be used to facilitate researchers’understandings of the underlying constructs or hypothetical factors and their magnitude of effect that constitute a complex system.This enhanced understanding,in turn,can help emphasize the important factors to improve mine safety.The most commonly used techniques include the exploratory factor analysis(EFA),the confirmatory factor analysis(CFA)and the structural equation model with latent variables(SEM).A critical comparison of the three techniques regarding mine safety is provided.Possible applications of latent variable modeling in mining engineering are explored.In this scope,relevant research papers were reviewed.They suggest that the application of such methods could prove useful in mine accident and safety research.Application of latent variables analysis in cognitive work analysis was proposed to improve the understanding of human-work relationships in mining operations.展开更多
Conformal invariance and conserved quantities of a general holonomic system with variable mass are studied. The definition and the determining equation of conformal invariance for a general holonomic system with varia...Conformal invariance and conserved quantities of a general holonomic system with variable mass are studied. The definition and the determining equation of conformal invariance for a general holonomic system with variable mass are provided. The conformal factor expression is deduced from conformal invariance and Lie symmetry. The relationship between the conformal invariance and the Lie symmetry is discussed, and the necessary and sufficient condition under which the conformal invariance would be the Lie symmetry of the system under an infinitesimal oneparameter transformation group is deduced. The conserved quantities of the system are given. An example is given to illustrate the application of the result.展开更多
A modified polarization saturation model is proposed and addressed math- ematically using a complex variable approach in two-dimensional (2D) semipermeable piezoelectric media. In this model, an existing polarizatio...A modified polarization saturation model is proposed and addressed math- ematically using a complex variable approach in two-dimensional (2D) semipermeable piezoelectric media. In this model, an existing polarization saturation (PS) model in 2D piezoelectric media is modified by considering a linearly varying saturated normal electric displacement load in place of a constant normal electric displacement load, applied on a saturated electric zone. A centre cracked infinite 2D piezoelectric domain subject to an arbitrary poling direction and in-plane electromechanical loadings is considered for the analytical and numerical studies. Here, the problem is mathematically modeled as a non-homogeneous Riemann-Hilbert problem in terms of unknown complex potential functions representing electric displacement and stress components. Having solved the Hilbert problem, the solutions to the saturated zone length, the crack opening displace- ment (COD), the crack opening potential (COP), and the local stress intensity factors (SIFs) are obtained in explicit forms. A numerical study is also presented for the proposed modified model, showing the effects of the saturation condition on the applied electrical loading, the saturation zone length, and the COP. The results of fracture parameters obtained from the proposed model are compared with the existing PS model subject to electrical loading, crack face conditions, and polarization angles.展开更多
In this review, single-chain fragment variable construction using phage-display technology as a promising anticancer immunotherapy technology is described. Cloning and the specific bio-panning selection with phage dis...In this review, single-chain fragment variable construction using phage-display technology as a promising anticancer immunotherapy technology is described. Cloning and the specific bio-panning selection with phage display technology, as well as the use of the epidermal growth factor receptor (EGFR) at the surface of MCF-7 cells as the antigen for the straightforward specific selection of single chain Fvs, are discussed. Moreover, phage display technologies and their application are important for vaccine production and immunotherapy against viruses and cancers. Furthermore, expression of the gene will cause the production and expression of the protein in prokaryotic and eukaryotic cells, which can be used to detect anti-cancer single chain fragment variables (scFvs). Finally, homology modelling is described to show the three-dimensional scFv structure that verifies the Complementary-Determining-Regions (CDRs) on the surface of the model.展开更多
The point and the line contacts of a toroidal continuously variable transmission (CVT) are studied. The contact shapes between the roller and input and output disks are formulated by using the classical Hertz contact ...The point and the line contacts of a toroidal continuously variable transmission (CVT) are studied. The contact shapes between the roller and input and output disks are formulated by using the classical Hertz contact theory. Based on the formulated equations, different system factors affecting the maximum Hertz stress in the elliptical and strip contacts of the full toroidal CVT are explored, which include the properties of the contacting material (Young’s modulus), operating condition (pushing load) and geometrical parameters (aspect cavity ratio, aspect roller ratio). The comparative results reveal the relations between the maximum Hertz stress and the speed ratio in the form of graphs. These graphs give useful information for designer to know the maximum Hertz stress during operation in such systems.展开更多
Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascad...Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascaded full bridge inverter operation with dissimilar (unequal) DC Source and it is fired by using variable frequency pulse with modulation technique as a switching strategy. This pulse width modulation switching strategy has a newly adopted multicarrier single reference technique. The performance parameter factors like Form Factor (FF), Crest Factor (CF), Total Harmonic Distortion (THD) and fundamental RMS output voltage (V<sub>RMS</sub>) are estimated by using proposed asymmetrical three-phase cascading multilevel inverter for several modulation indices (0.8 - 1). The research study carries with MATLAB/SIMULINK based simulation and experimental results obtained using appropriate prototype (test board) to prove the viability of the proposed concept.展开更多
Aim The general arbitrary cracked problem in an elastic plane was discussed. Methods For the purpose of acquiring the solution of the problem, a new formulation on the problem was proposed. Compared with the classic...Aim The general arbitrary cracked problem in an elastic plane was discussed. Methods For the purpose of acquiring the solution of the problem, a new formulation on the problem was proposed. Compared with the classical plane elastic crack model, only the known conditions were revised in the new formulation, which are greatly convenient to solve the problem, and no other new condition was given. Results and Conclusion The general exact analytic solution is given here based on the formulation though the problem is very complicated. Furthermore, the stress intensity factors K Ⅰ, K Ⅱ of the problem are also given.展开更多
背景:骨质疏松性骨折是骨质疏松症最严重的并发症,既往的研究已经证实了肠道菌群对骨骼组织具有调节作用,肠道菌群与骨质疏松性骨折有着重要关系,但是二者之间的因果关系尚不清楚。目的:使用孟德尔随机化(MR)方法探索肠道菌群与骨质疏...背景:骨质疏松性骨折是骨质疏松症最严重的并发症,既往的研究已经证实了肠道菌群对骨骼组织具有调节作用,肠道菌群与骨质疏松性骨折有着重要关系,但是二者之间的因果关系尚不清楚。目的:使用孟德尔随机化(MR)方法探索肠道菌群与骨质疏松性骨折之间的因果关系。方法:从IEU Open GWAS数据库和芬兰数据库R9中分别获得了肠道菌群和骨质疏松性骨折的GWAS数据集,以肠道菌群作为暴露因素,骨质疏松性骨折作为结局变量,采用随机效应逆方差加权法、MR-Egger回归、加权中位数法、简单模型法以及加权模型法进行孟德尔随机化分析来评估肠道菌群与骨质疏松性骨折之间是否存在因果关系,通过敏感性分析来检验结果的可靠性和稳健性,并进行反向孟德尔随机化分析来进一步验证正向孟德尔随机化分析中确定的因果关系。结果与结论:①此孟德尔随机化分析结果表明,肠道菌群与骨质疏松性骨折之间存在因果关系。放线菌目(OR=1.562,95%CI:1.027-2.375,P=0.037)、放线菌科(OR=1.561,95%CI:1.027-2.374,P=0.037)、放线菌属(OR=1.544,95%CI:1.130-2.110,P=0.006)、丁酸球菌属(OR=1.781,95%CI:1.194-2.657,P=0.005)、粪球菌属-2(OR=1.550,95%CI:1.068-2.251,P=0.021)、Family ⅩⅢ UCG-001属(OR=1.473,95%CI:1.001-2.168,P=0.049)、产甲烷短杆菌属(OR=1.274,95%CI:1.001-1.621,P=0.049)、罗氏菌属(OR=1.429,95%CI:1.015-2.013,P=0.041)的丰度升高,会增加患者骨质疏松性骨折的风险;②拟杆菌纲(OR=0.660,95%CI:0.455-0.959,P=0.029)、拟杆菌目(OR=0.660,95%CI:0.455-0.959,P=0.029)、克里斯滕森氏菌科(OR=0.725,95%CI:0.529-0.995,P=0.047)、瘤胃球菌科(OR=0.643,95%CI:0.443-0.933,P=0.020)、肠杆菌属(OR=0.558,95%CI:0.395-0.788,P=0.001)、直肠真杆菌属(OR=0.631,95%CI:0.435-0.916,P=0.016)、毛螺菌科-UCG008(OR=0.738,95%CI:0.546-0.998,P=0.048)、瘤胃梭菌属-9(OR=0.492,95%CI:0.324-0.746,P=0.001)的丰度升高,会降低患者骨质疏松性骨折的风险。③文章通过孟德尔随机化方法发现了16种与骨质疏松性骨折相关的肠道菌群,即以肠道菌群为暴露因素,骨质疏松性骨折为结局变量,8种肠道菌群与骨质疏松性骨折呈正向因果关联,另外8种肠道菌群与骨质疏松性骨折呈负向因果关联。④此研究结果不仅为临床上骨质疏松性骨折的早期预测及潜在治疗靶点确定了新的生物标志物,还为骨组织工程中研究通过肠道菌群改善骨质疏松性骨折的发生与预后提供了实验基础和理论依据。展开更多
Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we ev...Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive area.Results indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in details.The nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 cm.Soil organic matter was the controlling factor on the spatial variability of soil bulk density in each layer.Land use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,respectively.Soil genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.展开更多
Cardiac autonomic neuropathy(CAN)is a serious complication of diabetes mellitus(DM)that is strongly associated with approximately five-fold increased risk of cardiovascular mortality.CAN manifests in a spectrum of thi...Cardiac autonomic neuropathy(CAN)is a serious complication of diabetes mellitus(DM)that is strongly associated with approximately five-fold increased risk of cardiovascular mortality.CAN manifests in a spectrum of things,ranging from resting tachycardia and fixed heart rate(HR)to development of"silent"myocardial infarction.Clinical correlates or risk markers for CAN are age,DM duration,glycemic control,hypertension,and dyslipidemia(DLP),development of other microvascular complications.Established risk factors for CAN are poor glycemic control in type 1 DM and a combination of hypertension,DLP,obesity,and unsatisfactory glycemic control in type 2DM.Symptomatic manifestations of CAN include sinus tachycardia,exercise intolerance,orthostatic hypotension(OH),abnormal blood pressure(BP)regulation,dizziness,presyncope and syncope,intraoperative cardiovascular instability,asymptomatic myocardial ischemia and infarction.Methods of CAN assessment in clinical practice include assessment of symptoms and signs,cardiovascular reflex tests based on HR and BP,short-term electrocardiography(ECG),QT interval prolongation,HR variability(24 h,classic24 h Holter ECG),ambulatory BP monitoring,HR turbulence,baroreflex sensitivity,muscle sympathetic nerve activity,catecholamine assessment and cardiovascular sympathetic tests,heart sympathetic imaging.Although it is common complication,the significance of CAN has not been fully appreciated and there are no unified treatment algorithms for today.Treatment is based on early diagnosis,life style changes,optimization of glycemic control and management of cardiovascular risk factors.Pathogenetic treatment of CAN includes:Balanced diet and physical activity;optimization of glycemic control;treatment of DLP;antioxidants,first of allα-lipoic acid(ALA),aldose reductase inhibitors,acetylL-carnitine;vitamins,first of all fat-soluble vitamin B1;correction of vascular endothelial dysfunction;prevention and treatment of thrombosis;in severe cases-treatment of OH.The promising methods include prescription of prostacyclin analogues,thromboxane A2 blockers and drugs that contribute into strengthening and/or normalization of Na^+,K^+-ATPase(phosphodiesterase inhibitor),ALA,dihomo-γ-linolenic acid(DGLA),ω-3 polyunsaturated fatty acids(ω-3 PUFAs),and the simultaneous prescription of ALA,ω-3 PUFAs and DGLA,but the future investigations are needed.Development of OH is associated with severe or advanced CAN and prescription of nonpharmacological and pharmacological,in the foreground midodrine and fludrocortisone acetate,treatment methods are necessary.展开更多
The existing analytical solutions are extended to obtain the stress fields and the stress intensity factors(SIFs) of two unequal aligned cracks emanating from an elliptical hole in an infinite isotropic plane. A confo...The existing analytical solutions are extended to obtain the stress fields and the stress intensity factors(SIFs) of two unequal aligned cracks emanating from an elliptical hole in an infinite isotropic plane. A conformal mapping is proposed and combined with the complex variable method. Due to some difficulties in the calculation of the stress function, the mapping function is approximated and simplified via the applications of the series expansion. To validate the obtained solution, several examples are analyzed with the proposed method, the finite element method, etc. In addition, the effects of the lengths of the cracks and the ratio of the semi-axes of the elliptical hole(a/b) on the SIFs are studied. The results show that the present analytical solution is applicable to the SIFs for small cracks.展开更多
The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions.Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet ...The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions.Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study.The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree(CART) is adopted to identify the main controlling factors influencing the soil moisture movement. The relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis(CCA). The results show that: 1) Due to the terrain slope and the freezing-thawing process, the horizontal flow weakens in the freezing period. The vertical migration of the soil moisture movement strengthens. It will lead to that the soil-moisture content in the up-slope is higher than that in the down-slope. The conclusion is contrary during the melting period. 2) Elevation, soil texture, soil temperature and vegetation coverage are the main environmental factors which affect the slopepermafrost soil-moisture. 3) Slope, elevation and vegetation coverage are the main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20 cm. It is complex at the middle and lower depth.展开更多
Aiming at the intervention decision-making problem in manned/unmanned aerial vehicle(MAV/UAV) cooperative engagement, this paper carries out a research on allocation strategy of emergency discretion based on human f...Aiming at the intervention decision-making problem in manned/unmanned aerial vehicle(MAV/UAV) cooperative engagement, this paper carries out a research on allocation strategy of emergency discretion based on human factors engineering(HFE).Firstly, based on the brief review of research status of HFE, it gives structural description to emergency in the process of cooperative engagement and analyzes intervention of commanders. After that,constraint conditions of intervention decision-making of commanders based on HFE(IDMCBHFE) are given, and the mathematical model, which takes the overall efficiency value of handling emergencies as the objective function, is established. Then, through combining K-best and variable neighborhood search(VNS) algorithm, a K-best optimization variable neighborhood search mixed algorithm(KBOVNSMA) is designed to solve the model. Finally,through three groups of simulation experiments, effectiveness and superiority of the proposed algorithm are verified.展开更多
This investigation assessed the efficacy of 10 widely used machine learning algorithms(MLA)comprising the least absolute shrinkage and selection operator(LASSO),generalized linear model(GLM),stepwise generalized linea...This investigation assessed the efficacy of 10 widely used machine learning algorithms(MLA)comprising the least absolute shrinkage and selection operator(LASSO),generalized linear model(GLM),stepwise generalized linear model(SGLM),elastic net(ENET),partial least square(PLS),ridge regression,support vector machine(SVM),classification and regression trees(CART),bagged CART,and random forest(RF)for gully erosion susceptibility mapping(GESM)in Iran.The location of 462 previously existing gully erosion sites were mapped through widespread field investigations,of which 70%(323)and 30%(139)of observations were arbitrarily divided for algorithm calibration and validation.Twelve controlling factors for gully erosion,namely,soil texture,annual mean rainfall,digital elevation model(DEM),drainage density,slope,lithology,topographic wetness index(TWI),distance from rivers,aspect,distance from roads,plan curvature,and profile curvature were ranked in terms of their importance using each MLA.The MLA were compared using a training dataset for gully erosion and statistical measures such as RMSE(root mean square error),MAE(mean absolute error),and R-squared.Based on the comparisons among MLA,the RF algorithm exhibited the minimum RMSE and MAE and the maximum value of R-squared,and was therefore selected as the best model.The variable importance evaluation using the RF model revealed that distance from rivers had the highest significance in influencing the occurrence of gully erosion whereas plan curvature had the least importance.According to the GESM generated using RF,most of the study area is predicted to have a low(53.72%)or moderate(29.65%)susceptibility to gully erosion,whereas only a small area is identified to have a high(12.56%)or very high(4.07%)susceptibility.The outcome generated by RF model is validated using the ROC(Receiver Operating Characteristics)curve approach,which returned an area under the curve(AUC)of 0.985,proving the excellent forecasting ability of the model.The GESM prepared using the RF algorithm can aid decision-makers in targeting remedial actions for minimizing the damage caused by gully erosion.展开更多
基金supported by National Key Research and Development Program of China(2020YFB0505803)National Key Research and Development Program of China(2016YFB0501700)。
文摘The proportionate recursive least squares(PRLS)algorithm has shown faster convergence and better performance than both proportionate updating(PU)mechanism based least mean squares(LMS)algorithms and RLS algorithms with a sparse regularization term.In this paper,we propose a variable forgetting factor(VFF)PRLS algorithm with a sparse penalty,e.g.,l_(1)-norm,for sparse identification.To reduce the computation complexity of the proposed algorithm,a fast implementation method based on dichotomous coordinate descent(DCD)algorithm is also derived.Simulation results indicate superior performance of the proposed algorithm.
基金supported by the National Natural Science Foundation of China(42171129)the second Tibetan Plateau Scientific Expedition and Research(2019QZKK0208)Yunnan University Talent Introduction Research Project(YJRC3201702)。
文摘Land surface evapotranspiration(ET)is a critical component in the hydrological cycle but has not well been understood in data-scarce areas especially in river basins,like Nujiang River(NRB)which is characterized by large elevation gradient and different vegetation zones with complex processes of water and energy exchange.The quality of ET from optical remote sensing is constrained by cloud cover which is common in the NRB in the monsoon seasons.To understand factors controlling the spatial-temporal heterogeneity of ET in NRB,we employed the Variable Infiltration Capacity(VIC)hydrological model by parameter optimization with support of quality controlled remote sensing ET product and observed river runoff series in the river.The modeled ET has increased during 1984-2018,which might be one of the reasons for the runoff decrease but precipitation increase in the same period.ET increase and runoff decrease tended to be quicker within altitudinal band of 2000-4000 m than in other areas in NRB.We observed that ET variation in different climatic zones were controlled by different factors.ET is generally positively correlated with precipitation,temperature,and shortwave radiation but negatively with relative humidity.In the Tundra Climate(Et)zone in the upper reach of NRB,ET is controlled by precipitation,while it is controlled by shortwave radiation in the snow climate with dry winter(Dw)zone.ET increase is influenced by the increase of temperature,wind speed,and shortwave radiation in the middle and downstream of NRB with warm temperate climate,fully humid(Cf)and warm temperate climate with dry winter(Cw).
文摘Variability in soil properties is a critical element across wide areas of researches especially in several aspects of agriculture and environment including sewage disposal and global climate change. Particle size fraction (sand, silt, and clay), effective cation exchange capacity, base saturation, pH, organic carbon, total nitrogen, carbon nitrogen ratio, available phosphorus, exchangeable bases (calcium, magnesium, sodium, potassium) and acidity are frequently used in agriculture for soil management. The objective of this study therefore was to identify soil management factors from these set of 15 soil properties and spatial distribution of representative soil management properties. The study was carried out in the University of Uyo Teaching and Research Farm measuring 8.19 hectares in University of Uyo Annex, Uyo in Akwa Ibom State of Nigeria. Nine and ten traverses were made horizontally and vertically respectively at 40 meters intervals. A total of 58 soil samples were collected at 0 - 15 cm depth on the grid nodes of the traverses. Particle size distributions, exchangeable bases and acidity, effective cation exchange capacity (ECEC), available phosphorus (avail. P), base saturation (BS), organic carbon, total nitrogen, carbon nitrogen ratio (CNR) and pH of the samples were determined in the laboratory. Coefficient of variation indicated that 26.6% of the soil properties (sand content, pH, CNR and sodium) were least variable, 40.1% comprising silt, clay contents, ECEC, base saturation, phosphorus and magnesium were moderately. Whereas 33.3% of the soil properties comprising clay content, organic carbon, total nitrogen, exchangeable Ca, K and acidity (i.e.) were highly variable. There were significant correlation (p < 0.05) in 26.6% of the soil properties, the strongest negative significant (p < 0.01) correlations were between sand and clay (r = –0.85), exchangeable acidity and base saturation (r = –0.85), whereas the strongest positive significant correlations were between ECEC and Ca (r = 0.80), Ca and BS (r = 0.74), organic carbon and total nitrogen (r = 0.80). Principal component analysis indicated the existence of six factors including mineralogical or weathering, soil organic matter, cation exchange activity, soil texture, and dispersion and soil phosphorus based on either management or pedological considerations. Semivariance statistics showed that sand and clay contents, ECEC, BS and total N were moderately (≥25.7% ≤47.3%), while silt content, pH, organic carbon, CNR, avail. P, exchangeable Ca, Mg, Na and acidity (≥0.18% ≤22.8%) were strongly spatially dependent. The variability observed was primarily incident upon factors of soil formation. Therefore, the utilization of spatial structure of organic matter and texture factors in the management of nutrient and soil water will facilitate planning of crop production scheme on coastal plain sands soils.
文摘For a century, hypothesis of a variable time is laid down by the Relativity Theory. This hypothesis can explain many Nature observations, experiments and formulas, for example the Lorentz factor demonstration. Because of such good explanations, the hypothesis of a variable time has been validated. Nevertheless, it remains some paradoxes and some predictions which are difficult to measure, as a reversible time or the time variation itself. The purpose of this article is to study another hypothesis. If it gives interesting results, it would mean that this alternative hypothesis can also be validated. The idea in this paper is to replace the variable time by a variable inertial mass. To the difference with the Theory of Relativity (where the inertial mass and the gravitational mass are equal and variable), the gravitational mass is here supposed to be constant. So, starting from the definition of the kinetic energy, it is introduced the Lorentz factor. And then it is demonstrated the value of the Lorentz factor thanks to a variable inertial mass. This variable inertial mass can also explain experiments, like Bertozzi experiment. If this alternative demonstration was validated, it could help to open doors, other physical effects could be explained like the addition of velocities.
基金supported by the National Natural Science Foundation of China(7177121671701209)
文摘Artificial bee colony(ABC) is one of the most popular swarm intelligence optimization algorithms which have been widely used in numerical optimization and engineering applications. However, there are still deficiencies in ABC regarding its local search ability and global search efficiency. Aiming at these deficiencies,an ABC variant named hybrid ABC(HABC) algorithm is proposed.Firstly, the variable neighborhood search factor is added to the solution search equation, which can enhance the local search ability and increase the population diversity. Secondly, inspired by the neuroscience investigation of real honeybees, the memory mechanism is put forward, which assumes the artificial bees can remember their past successful experiences and further guide the subsequent foraging behavior. The proposed memory mechanism is used to improve the global search efficiency. Finally, the results of comparison on a set of ten benchmark functions demonstrate the superiority of HABC.
基金Natural Sciences and Engineering Research Council of Canada(NSERC)(ID:236482)for supporting this research
文摘This paper discusses the utilization of latent variable modeling related to occupational health and safety in the mining industry.Latent variable modeling,which is a statistical model that relates observable and latent variables,could be used to facilitate researchers’understandings of the underlying constructs or hypothetical factors and their magnitude of effect that constitute a complex system.This enhanced understanding,in turn,can help emphasize the important factors to improve mine safety.The most commonly used techniques include the exploratory factor analysis(EFA),the confirmatory factor analysis(CFA)and the structural equation model with latent variables(SEM).A critical comparison of the three techniques regarding mine safety is provided.Possible applications of latent variable modeling in mining engineering are explored.In this scope,relevant research papers were reviewed.They suggest that the application of such methods could prove useful in mine accident and safety research.Application of latent variables analysis in cognitive work analysis was proposed to improve the understanding of human-work relationships in mining operations.
基金Project supported by the Key Disciplines’ Building Foundation of Henan Institute of Educationthe Natural Science Foundation of Education Bureau of Henan Province,China (Grant No. 2009A140003)the Young Core Instructor from Henan Institute of Education
文摘Conformal invariance and conserved quantities of a general holonomic system with variable mass are studied. The definition and the determining equation of conformal invariance for a general holonomic system with variable mass are provided. The conformal factor expression is deduced from conformal invariance and Lie symmetry. The relationship between the conformal invariance and the Lie symmetry is discussed, and the necessary and sufficient condition under which the conformal invariance would be the Lie symmetry of the system under an infinitesimal oneparameter transformation group is deduced. The conserved quantities of the system are given. An example is given to illustrate the application of the result.
文摘A modified polarization saturation model is proposed and addressed math- ematically using a complex variable approach in two-dimensional (2D) semipermeable piezoelectric media. In this model, an existing polarization saturation (PS) model in 2D piezoelectric media is modified by considering a linearly varying saturated normal electric displacement load in place of a constant normal electric displacement load, applied on a saturated electric zone. A centre cracked infinite 2D piezoelectric domain subject to an arbitrary poling direction and in-plane electromechanical loadings is considered for the analytical and numerical studies. Here, the problem is mathematically modeled as a non-homogeneous Riemann-Hilbert problem in terms of unknown complex potential functions representing electric displacement and stress components. Having solved the Hilbert problem, the solutions to the saturated zone length, the crack opening displace- ment (COD), the crack opening potential (COP), and the local stress intensity factors (SIFs) are obtained in explicit forms. A numerical study is also presented for the proposed modified model, showing the effects of the saturation condition on the applied electrical loading, the saturation zone length, and the COP. The results of fracture parameters obtained from the proposed model are compared with the existing PS model subject to electrical loading, crack face conditions, and polarization angles.
文摘In this review, single-chain fragment variable construction using phage-display technology as a promising anticancer immunotherapy technology is described. Cloning and the specific bio-panning selection with phage display technology, as well as the use of the epidermal growth factor receptor (EGFR) at the surface of MCF-7 cells as the antigen for the straightforward specific selection of single chain Fvs, are discussed. Moreover, phage display technologies and their application are important for vaccine production and immunotherapy against viruses and cancers. Furthermore, expression of the gene will cause the production and expression of the protein in prokaryotic and eukaryotic cells, which can be used to detect anti-cancer single chain fragment variables (scFvs). Finally, homology modelling is described to show the three-dimensional scFv structure that verifies the Complementary-Determining-Regions (CDRs) on the surface of the model.
基金Funded by the Ford-NSFC Foundation of China (No.50122151).
文摘The point and the line contacts of a toroidal continuously variable transmission (CVT) are studied. The contact shapes between the roller and input and output disks are formulated by using the classical Hertz contact theory. Based on the formulated equations, different system factors affecting the maximum Hertz stress in the elliptical and strip contacts of the full toroidal CVT are explored, which include the properties of the contacting material (Young’s modulus), operating condition (pushing load) and geometrical parameters (aspect cavity ratio, aspect roller ratio). The comparative results reveal the relations between the maximum Hertz stress and the speed ratio in the form of graphs. These graphs give useful information for designer to know the maximum Hertz stress during operation in such systems.
文摘Asymmetric three-phase cascading Trinary-DC source Multilevel Inverter which can achieve reduced harmonics and superior root mean square (RMS) values of the output voltage is proposed. This topology can achieve cascaded full bridge inverter operation with dissimilar (unequal) DC Source and it is fired by using variable frequency pulse with modulation technique as a switching strategy. This pulse width modulation switching strategy has a newly adopted multicarrier single reference technique. The performance parameter factors like Form Factor (FF), Crest Factor (CF), Total Harmonic Distortion (THD) and fundamental RMS output voltage (V<sub>RMS</sub>) are estimated by using proposed asymmetrical three-phase cascading multilevel inverter for several modulation indices (0.8 - 1). The research study carries with MATLAB/SIMULINK based simulation and experimental results obtained using appropriate prototype (test board) to prove the viability of the proposed concept.
文摘Aim The general arbitrary cracked problem in an elastic plane was discussed. Methods For the purpose of acquiring the solution of the problem, a new formulation on the problem was proposed. Compared with the classical plane elastic crack model, only the known conditions were revised in the new formulation, which are greatly convenient to solve the problem, and no other new condition was given. Results and Conclusion The general exact analytic solution is given here based on the formulation though the problem is very complicated. Furthermore, the stress intensity factors K Ⅰ, K Ⅱ of the problem are also given.
文摘背景:骨质疏松性骨折是骨质疏松症最严重的并发症,既往的研究已经证实了肠道菌群对骨骼组织具有调节作用,肠道菌群与骨质疏松性骨折有着重要关系,但是二者之间的因果关系尚不清楚。目的:使用孟德尔随机化(MR)方法探索肠道菌群与骨质疏松性骨折之间的因果关系。方法:从IEU Open GWAS数据库和芬兰数据库R9中分别获得了肠道菌群和骨质疏松性骨折的GWAS数据集,以肠道菌群作为暴露因素,骨质疏松性骨折作为结局变量,采用随机效应逆方差加权法、MR-Egger回归、加权中位数法、简单模型法以及加权模型法进行孟德尔随机化分析来评估肠道菌群与骨质疏松性骨折之间是否存在因果关系,通过敏感性分析来检验结果的可靠性和稳健性,并进行反向孟德尔随机化分析来进一步验证正向孟德尔随机化分析中确定的因果关系。结果与结论:①此孟德尔随机化分析结果表明,肠道菌群与骨质疏松性骨折之间存在因果关系。放线菌目(OR=1.562,95%CI:1.027-2.375,P=0.037)、放线菌科(OR=1.561,95%CI:1.027-2.374,P=0.037)、放线菌属(OR=1.544,95%CI:1.130-2.110,P=0.006)、丁酸球菌属(OR=1.781,95%CI:1.194-2.657,P=0.005)、粪球菌属-2(OR=1.550,95%CI:1.068-2.251,P=0.021)、Family ⅩⅢ UCG-001属(OR=1.473,95%CI:1.001-2.168,P=0.049)、产甲烷短杆菌属(OR=1.274,95%CI:1.001-1.621,P=0.049)、罗氏菌属(OR=1.429,95%CI:1.015-2.013,P=0.041)的丰度升高,会增加患者骨质疏松性骨折的风险;②拟杆菌纲(OR=0.660,95%CI:0.455-0.959,P=0.029)、拟杆菌目(OR=0.660,95%CI:0.455-0.959,P=0.029)、克里斯滕森氏菌科(OR=0.725,95%CI:0.529-0.995,P=0.047)、瘤胃球菌科(OR=0.643,95%CI:0.443-0.933,P=0.020)、肠杆菌属(OR=0.558,95%CI:0.395-0.788,P=0.001)、直肠真杆菌属(OR=0.631,95%CI:0.435-0.916,P=0.016)、毛螺菌科-UCG008(OR=0.738,95%CI:0.546-0.998,P=0.048)、瘤胃梭菌属-9(OR=0.492,95%CI:0.324-0.746,P=0.001)的丰度升高,会降低患者骨质疏松性骨折的风险。③文章通过孟德尔随机化方法发现了16种与骨质疏松性骨折相关的肠道菌群,即以肠道菌群为暴露因素,骨质疏松性骨折为结局变量,8种肠道菌群与骨质疏松性骨折呈正向因果关联,另外8种肠道菌群与骨质疏松性骨折呈负向因果关联。④此研究结果不仅为临床上骨质疏松性骨折的早期预测及潜在治疗靶点确定了新的生物标志物,还为骨组织工程中研究通过肠道菌群改善骨质疏松性骨折的发生与预后提供了实验基础和理论依据。
基金supported by the National Natural Science Foundation of China (4120124)the Science Fund of the Education Department of Sichuan Province, China (16ZB0048)
文摘Soil bulk density is a basic but important physic soil property related to soil porosity,soil moisture and hydraulic conductivity,which is crucial to soil quality assessment and land use management.In this study,we evaluated the spatial variability of soil bulk density in the 0–20,20–40,40–60 and 60–100 cm layers as well as its affecting factors in Southwest China’s agricultural intensive area.Results indicated the mean value of surface soil bulk density(0–20 cm)was 1.26 g cm^(–3),significantly lower than that of subsoil(20–100 cm).No statistical difference existed among the subsoil with a mean soil bulk density of 1.54 g cm^(–3).Spatially,soil bulk density played a similar spatial pattern in soil profile,whereas obvious differences were found in details.The nugget effects for soil bulk density in the 0–20 and 20–40 cm layers were 27.22 and27.02%while 12.06 and 3.46%in the 40–60 and 60–100 cm layers,respectively,gradually decreasing in the soil profile,indicating that the spatial variability of soil bulk density above 40 cm was affected by structural and random factors while dominated by structural factors under 40 cm.Soil organic matter was the controlling factor on the spatial variability of soil bulk density in each layer.Land use and elevation were another two dominated factor controlling the spatial variability of soil bulk density in the 0–20 and 40–60 cm layers,respectively.Soil genus was one of the dominated factors controlling the spatial variability of soil bulk below 40 cm.
文摘Cardiac autonomic neuropathy(CAN)is a serious complication of diabetes mellitus(DM)that is strongly associated with approximately five-fold increased risk of cardiovascular mortality.CAN manifests in a spectrum of things,ranging from resting tachycardia and fixed heart rate(HR)to development of"silent"myocardial infarction.Clinical correlates or risk markers for CAN are age,DM duration,glycemic control,hypertension,and dyslipidemia(DLP),development of other microvascular complications.Established risk factors for CAN are poor glycemic control in type 1 DM and a combination of hypertension,DLP,obesity,and unsatisfactory glycemic control in type 2DM.Symptomatic manifestations of CAN include sinus tachycardia,exercise intolerance,orthostatic hypotension(OH),abnormal blood pressure(BP)regulation,dizziness,presyncope and syncope,intraoperative cardiovascular instability,asymptomatic myocardial ischemia and infarction.Methods of CAN assessment in clinical practice include assessment of symptoms and signs,cardiovascular reflex tests based on HR and BP,short-term electrocardiography(ECG),QT interval prolongation,HR variability(24 h,classic24 h Holter ECG),ambulatory BP monitoring,HR turbulence,baroreflex sensitivity,muscle sympathetic nerve activity,catecholamine assessment and cardiovascular sympathetic tests,heart sympathetic imaging.Although it is common complication,the significance of CAN has not been fully appreciated and there are no unified treatment algorithms for today.Treatment is based on early diagnosis,life style changes,optimization of glycemic control and management of cardiovascular risk factors.Pathogenetic treatment of CAN includes:Balanced diet and physical activity;optimization of glycemic control;treatment of DLP;antioxidants,first of allα-lipoic acid(ALA),aldose reductase inhibitors,acetylL-carnitine;vitamins,first of all fat-soluble vitamin B1;correction of vascular endothelial dysfunction;prevention and treatment of thrombosis;in severe cases-treatment of OH.The promising methods include prescription of prostacyclin analogues,thromboxane A2 blockers and drugs that contribute into strengthening and/or normalization of Na^+,K^+-ATPase(phosphodiesterase inhibitor),ALA,dihomo-γ-linolenic acid(DGLA),ω-3 polyunsaturated fatty acids(ω-3 PUFAs),and the simultaneous prescription of ALA,ω-3 PUFAs and DGLA,but the future investigations are needed.Development of OH is associated with severe or advanced CAN and prescription of nonpharmacological and pharmacological,in the foreground midodrine and fludrocortisone acetate,treatment methods are necessary.
文摘The existing analytical solutions are extended to obtain the stress fields and the stress intensity factors(SIFs) of two unequal aligned cracks emanating from an elliptical hole in an infinite isotropic plane. A conformal mapping is proposed and combined with the complex variable method. Due to some difficulties in the calculation of the stress function, the mapping function is approximated and simplified via the applications of the series expansion. To validate the obtained solution, several examples are analyzed with the proposed method, the finite element method, etc. In addition, the effects of the lengths of the cracks and the ratio of the semi-axes of the elliptical hole(a/b) on the SIFs are studied. The results show that the present analytical solution is applicable to the SIFs for small cracks.
基金supported by the National Natural Science Foundation of China(Grant No.41501079 and 91647103)Funded by State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE-ZQ-43)+1 种基金the Chinese Academy of Sciences(CAS)Key Research Program(Grant No.KZZD-EW-13)the Foundation for Excellent Youth Scholars of NIEER,CAS
文摘The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions.Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study.The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree(CART) is adopted to identify the main controlling factors influencing the soil moisture movement. The relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis(CCA). The results show that: 1) Due to the terrain slope and the freezing-thawing process, the horizontal flow weakens in the freezing period. The vertical migration of the soil moisture movement strengthens. It will lead to that the soil-moisture content in the up-slope is higher than that in the down-slope. The conclusion is contrary during the melting period. 2) Elevation, soil texture, soil temperature and vegetation coverage are the main environmental factors which affect the slopepermafrost soil-moisture. 3) Slope, elevation and vegetation coverage are the main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20 cm. It is complex at the middle and lower depth.
基金supported by the National Natural Science Foundation of China(61573017)the Doctoral Foundation of Air Force Engineering University(KGD08101604)
文摘Aiming at the intervention decision-making problem in manned/unmanned aerial vehicle(MAV/UAV) cooperative engagement, this paper carries out a research on allocation strategy of emergency discretion based on human factors engineering(HFE).Firstly, based on the brief review of research status of HFE, it gives structural description to emergency in the process of cooperative engagement and analyzes intervention of commanders. After that,constraint conditions of intervention decision-making of commanders based on HFE(IDMCBHFE) are given, and the mathematical model, which takes the overall efficiency value of handling emergencies as the objective function, is established. Then, through combining K-best and variable neighborhood search(VNS) algorithm, a K-best optimization variable neighborhood search mixed algorithm(KBOVNSMA) is designed to solve the model. Finally,through three groups of simulation experiments, effectiveness and superiority of the proposed algorithm are verified.
基金supported by the College of Agriculture,Shiraz University(Grant No.97GRC1M271143)funding from the UK Biotechnology and Biological Sciences Research Council(BBSRC)funded by BBSRC grant award BBS/E/C/000I0330–Soil to Nutrition project 3–Sustainable intensification:optimisation at multiple scales。
文摘This investigation assessed the efficacy of 10 widely used machine learning algorithms(MLA)comprising the least absolute shrinkage and selection operator(LASSO),generalized linear model(GLM),stepwise generalized linear model(SGLM),elastic net(ENET),partial least square(PLS),ridge regression,support vector machine(SVM),classification and regression trees(CART),bagged CART,and random forest(RF)for gully erosion susceptibility mapping(GESM)in Iran.The location of 462 previously existing gully erosion sites were mapped through widespread field investigations,of which 70%(323)and 30%(139)of observations were arbitrarily divided for algorithm calibration and validation.Twelve controlling factors for gully erosion,namely,soil texture,annual mean rainfall,digital elevation model(DEM),drainage density,slope,lithology,topographic wetness index(TWI),distance from rivers,aspect,distance from roads,plan curvature,and profile curvature were ranked in terms of their importance using each MLA.The MLA were compared using a training dataset for gully erosion and statistical measures such as RMSE(root mean square error),MAE(mean absolute error),and R-squared.Based on the comparisons among MLA,the RF algorithm exhibited the minimum RMSE and MAE and the maximum value of R-squared,and was therefore selected as the best model.The variable importance evaluation using the RF model revealed that distance from rivers had the highest significance in influencing the occurrence of gully erosion whereas plan curvature had the least importance.According to the GESM generated using RF,most of the study area is predicted to have a low(53.72%)or moderate(29.65%)susceptibility to gully erosion,whereas only a small area is identified to have a high(12.56%)or very high(4.07%)susceptibility.The outcome generated by RF model is validated using the ROC(Receiver Operating Characteristics)curve approach,which returned an area under the curve(AUC)of 0.985,proving the excellent forecasting ability of the model.The GESM prepared using the RF algorithm can aid decision-makers in targeting remedial actions for minimizing the damage caused by gully erosion.