Information content method for evaluating diagnostic tests and its comparison of power with other methods

This paper derives the variance of the information content and develops its statistical inference method. We describe the relations between information content and sensitivity, specificity, efficiency, prevalence rate. If sensitivity, specificity and efficiency are fixed, the closer to 0. 5 the prevalence rate is, the more the information content. If prevalence rate and efficiency are fixed, the closer to each other the sensitivity and specificity are, the more the information content. We compare the power of information content method, efficiecy test, Youden's index test and kappa coefficient method. The information content method has higher power than the other methods in most conditions. It is especially sensitive to the difference between two sensitivities. It comes to conclusion that the information content method has more virtues than the other methods mentioned in this paper.

A Calculation Method of Double Strength Reduction for Layered Slope Based on the Reduction of Water Content Intensity

The calculation of the factor of safety(FOS)is an important means of slope evaluation.This paper proposed an improved double strength reductionmethod(DRM)to analyze the safety of layered slopes.The physical properties of different soil layers of the slopes are different,so the single coefficient strength reduction method(SRM)is not enough to reflect the actual critical state of the slopes.Considering that the water content of the soil in the natural state is the main factor for the strength of the soil,the attenuation law of shear strength of clayey soil changing with water content is fitted.This paper also establishes the functional relationship between different reduction coefficients.Then,a USDFLD subroutine is programmed using the secondary development function of finite element software.Controlling the relationship between field variables and calculation time realizes double strength reduction applicable to the layered slope.Finally,by comparing the calculation results of different examples,it is proved that the stress and displacement distribution of the critical slope state obtained by the improved method is more realistic,and the calculated safety factor is more reliable.The newly proposedmethod considers the difference of intensity attenuation between different soil layers under natural conditions and avoids the disadvantage of the strength reduction method with uniform parameters,which provides a new idea and method for stability analysis of layered and complex slopes.

Influence of wind-blown sand content on the mechanical quality state of ballast bed in sandy railways

During the operation of sandy railways, the challenge posed by wind-blown sand is a persistent issue. An in-depth study on the influence of wind-blown sand content on the macroscopic and microscopic mechanical properties of the ballast bed is of great significance for understanding the potential problems of sandy railways and proposing reasonable and adequate maintenance and repair strategies. Building upon existing research, this study proposes a new assessment indicator for sand content. Utilizing the discrete element method(DEM) and fully considering the complex interactions between ballast and sand particles, three-dimensional(3D) multi-scale analysis models of sandy ballast beds with different wind-blown sand contents are established and validated through field experiments. The effects of varying wind-blown sand content on the microscopic contact distribution and macroscopic mechanical behavior(such as resistance and support stiffness) of ballast beds are carefully analyzed. The results show that with the increase in sand content, the average contact force and coordination number between ballast particles gradually decrease, and the disparity in contact forces between different layers of the ballast bed diminishes. The longitudinal and lateral resistance of the ballast bed initially decreases and then increases, with a critical point at 10% sand content. At 15% sand content, the lateral resistance is mainly shared by the ballast shoulder. The longitudinal resistance sharing ratio is always the largest on the sleeper side, followed by that at the sleeper bottom, and the smallest on the ballast shoulder. When the sand content exceeds 10%, the contribution of sand particles to stiffness significantly increases, leading to an accelerated growth rate of the overall support stiffness of the ballast bed, which is highly detrimental to the long-term service performance of the ballast bed. In conclusion, it is recommended that maintenance and repair operations should be promptly conducted when the sand content of the ballast bed reaches or exceeds 10%.

Analysis of the integrated test and evaluation methods of tidal current energy generating devices in the offshore testing site

Actual sea condition testing and inspection and evaluation method research are carried out for tidal energy devices to provide scientific and effective technical support for the ocean high-tech achievement transformation and marine renewable energy development. By analyzing three core indicators, including the power output characteristics of the tidal current device, the generating capacity, energy conversion efficiency, proposed the test contents and evaluation methods of indicators are proposed in this paper; and based on the research of wind farms, power quality testing and assessment methods of offshore tidal energy device are proposed; given the security access to the test contents of tidal current energy device, tidal current energy device running conditions in the testing ground are comprehensively assessed.

Oil Content Conversion between Ether-based and Ethanol-based Methods and Establishment of Admissible Error for Imported Wool

Due to various reasons, the inspection methods often need to be changed, and the detection reagents often need to be replaced. In this study, a comparative experiment was conducted between the ethanol-based and ether-based determination methods for oil content in imported wool. The determination results obtained from the two methods were treated as abscissa and ordinate respectively,and their linear relationship was analyzed. According to the linear regression analysis, the conversion equation of determination result between the two methods was obtained. In addition, the repeatability admissible error and reproducibility admissible error were established through analyzing the comparative experimental results by scientific software. This study will bring new ideas for further researches in this field, and provide reference for solving the similar problems in actual inspection work.

A rapid and accurate direct measurement method of underground coal seam gas content based on dynamic diffusion theory

Coal seam gas content is frequently measured in quantity during underground coal mining operation and coalbed methane(CBM)exploration as a significant basic parameter.Due to the calculation error of lost gas and residual gas in the direct method,the efficiency and accuracy of the current methods are not inadequate to the large area multi-point measurement of coal seam gas content.This paper firstly deduces a simplified theoretical dynamic model for calculating lost gas based on gas dynamic diffusion theory.Secondly,the effects of various factors on gas dynamic diffusion from coal particle are experimentally studied.And sampling procedure of representative coal particle is improved.Thirdly,a new estimation method of residual gas content based on excess adsorption and competitive adsorption theory is proposed.The results showed that the maximum error of calculating the losing gas content by using the new simplified model is only 4%.Considering the influence of particle size on gas diffusion law,the particle size of the collected coal sample is below 0.25 mm,which improves the measurement speed and reflects the safety representativeness of the sample.The determination time of gas content reduced from 36 to 3 h/piece.Moreover,the absolute error is 0.15–0.50 m^3/t,and the relative error is within 5%.A new engineering method for determining the coal seam gas content is developed according to the above research.

Load Reduction Test Method of Similarity Theory and BP Neural Networks of Large Cranes

Static load tests are an important means of supervising and detecting a crane＇s lift capacity. Due to space restrictions, however, there are difficulties and potential danger when testing large bridge cranes. To solve the loading problems of large-tonnage cranes during testing, an equivalency test is proposed based on the similarity theory and BP neural networks. The maximum stress and displacement of a large bridge crane is tested in small loads, combined with the training neural network of a similar structure crane through stress and displacement data which is collected by a physics simulation progressively loaded to a static load test load within the material scope of work. The maximum stress and displacement of a crane under a static load test load can be predicted through the relationship of stress, displacement, and load. By measuring the stress and displacement of small tonnage weights, the stress and displacement of large loads can be predicted, such as the maximum load capacity, which is 1.25 times the rated capacity. Experimental study shows that the load reduction test method can reflect the lift capacity of large bridge cranes. The load shedding predictive analysis for Sanxia 1200 t bridge crane test data indicates that when the load is 1.25 times the rated lifting capacity, the predicted displacement and actual displacement error is zero. The method solves the problem that lifting capacities are difficult to obtain and testing accidents are easily possible when 1.25 times related weight loads are tested for large tonnage cranes.

Non-Destructive Testing of Structures Using Optical and Other Methods: A Review

Non-destructive testing (NDT) of structures is one of the most important tasksof the proper maintenance and diagnosis of machines and constructions structuralcondition. NDT methods contribute to the damage tolerance philosophy used in theaircraft design methodology as well as many other operation and maintenance programsof machinery and constructions. The following study is focusing on overviewing animportant group of NDT methods: the optical and other ones, which found broadapplicability in scientific and industrial studies nowadays. The paper discusses theselected most widely applicable methods, namely, visual testing, ultrasonic testing,radiographic testing, infrared thermography as well as electronic speckle patterninterferometry and shearographic testing. Besides the basic principles of testing usingthese methods, their potential applications in various industrial and technologicalbranches are broadly discussed. The analysis as categorization of the NDT methodsprovided in this paper may help in selection of such methods in diagnosis of varioustypes of structures and defects and damage occurring in these structures.

Analysis of the Conditional Correlations from Different Genetic Systems Between the Protein Content and the Appearance Quality Traits of Indica Rice

A factorial mating design in two environments was conducted using 7 cytoplasmic male sterile lines （A） and 5 restorer lines （R） along with their F1 （A × R） and F2 populations. The unconditional and conditional analyses of genetic models and the corresponding statistic methods, including endospermic, cytoplasmic, and maternal plant genetic systems, were used to analyze the genetic relationships between protein content （PC） and the appearance quality traits of indica rice （Oryza sativa L.）. The results from unconditional analysis indicated that PC was significantly correlated with the appearance quality traits of rice, except for the brown rice thickness （BRT）. Only the genetic covariance between PC and the brown rice width （BRW） was positively correlative, whereas all the other pairwise traits were negatively correlative. The results from conditional analysis revealed that the weight of brown rice （WBR） or the amylose content （AC） could significantly affect the relationships between PC and the appearance quality traits of indica rice. The conditional analysis showed that WBR might negatively affect the relationships between PC and the brown rice length （BRL）, BRW, or BRT through the geuotype x environmental （GE） interaction effects, but positively affected the relationships between PC and the ratio of brown rice length to width （RLW） or the ratio of brown rice length to thickness （RLT）. The amylase content could positively affect the relationships between PC and BRL, RLW, RLT through the cytoplasmic effects and maternal additive effects, but negatively affected the relationships between PC and BRW.

Application of the extended Fourier amplitude sensitivity testing(FAST)method to inflated,axial stretched,and residually stressed cylinders

This paper is dedicated to applying the Fourier amplitude sensitivity test(FAST)method to the problem of mixed extension and inflation of a circular cylindrical tube in the presence of residual stresses.The metafunctions and the Ishigami function are considered in the sensitivity analysis(SA).The effects of the input variables on the output variables are investigated,and the most important parameters of the system under the applied pressure and axial force such as the axial stretch and the azimuthal stretch are determined.

Research on the Testing Methods of Instrumental System in the Marine Magnetic Survey

Testing methods of instrumental system in the marine magnetic survey have been studied in this paper, and the feasibility of each method has been testified by the observed data. The conclusion shows that the method brought out can effectively eliminate the systematic error caused by the instrumental system, and greatly improve the surveying precision and the reliability of the survey results.

ADPRT-MEDIATED DECREASE OF CELLULAR NAD CONTENT AND THE DETECTION OF CHEMICALLY INDUCED DNA DAMAGE DEVELOPMENT OF A NEW SHORT-TERM SCREENING TEST FOR MUTAGENS

It was found that the DNA-damaging agents N-methyl-N’-nitro-N-nitrosoguanidine（MNNG）,methyl-methanesulphonate（MMS）and 4-nitroquinoline-N-oxide（4NQO）could stimulate ADP-ribosyl transferase（ADPRT）activity and reduce the cellular NAD content in a dose-dependent way.The reduction of NAD after DNA damage could be partially or completelyprevented by ADPRT inhibitors,3-aminobenzamide or nicotinamide,which showed noinfluence on reduction of NAD induced by metabolic blocking agents.Therefore,a simpleand specific method to detect DNA-damaging mutagens by measuring ADPRT-mediateddecrease of cellular NAD content was explored.Using β-naphthofiavone,a mixed functionoxygenase inducer,together with induced or uninduced human amnion FL cells,it was foundthat aflatoxin B1,benzo（a）pyrene,2-acetylaminofluorene,9,10-dimethylanthracene andethylcarbamate could induce the ADPRT-mediated decrease of cellular NAD content,while4-acetylaminofluorene,anthracene,isopropyl-N-（3-chlorophenyl）-carbamate,β-propiolactone,γ-butyrolactone,cyclophosphamide and safrol could not.The results indicate that this isa cheap and specific method to detect DNA damage caused by chemical carcinogens/mutagenswith a spccificity approaching that of the unscheduled DNA synthesis assay.

A Review of the Methods of Identifying and Testing Plant Cold Resistance

Low-tempemture stress is a major abiotic stress influencing plant growth, economic yield and quality worldwide. Precise and reliable identification and test of plant cold resistance is a foundation for exploring low-temperature damages, cold resistance mechanism of plants, cultivating and innovating quality cold-re- sistant germplasm resources, which is rather important for woody plants because their perennial and large-sized characteristics. Generally, most researches on plant cold-resistant physiology focused on identification and utilization of cold resistance worldwide, and a few on test methods of cold resistance, but cold resistance mechanism has been less reported. Therefore, researches on methods of identifying and testing plant resistance have achieved considerable progress, accumulated much experience and formed characteristics gradually in terms of methodology. Current methods of identifying plant cold resistance include open field/outdoor culti- vation evaluation, cold and frost damage investigation, simulated cold weather, and mathematical model forecast. And the methods of testing plant cold resistance include growth condition test, frozen index investigation, electrolyte leakage, bioelectrical impedance mapping and so on. Synthesizing the methods of identifying and testing plant cold resistance should be a key matter in the present and future researches and application of plant cold resistance physiology, improvement and in- novation of the identification and test will be an important direction of the future researches. Identification and test of plant cold resistance based on genomies, meta- bonomics and proteomics should be the new trend of the researches on physiology and ecology of plant cold resistance.

The Testing Strength Curves of Lightweight Aggregate Concrete by Rebound Method and Ultrasonic-rebound Combined Method

The strength curves of lightweight aggregate concrete （LWAC） were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LC15-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.

Effect of Fine Content on the Bearing Capacity of Replaced Sand Gravely Subgrad-Field Test

The compacted soil replacement procedure has been widely used worldwide for overcoming the unfavorable actions of some problematic soils,such as expansive,collapsing soils and ground fill.Compaction of the replacement soil is necessary for stabilizing such layer for improving its performance.In this study,gravelly-sand soil,which consists of gravel,sand and fines,is widely used as replacement soil in the field.The effect of fines content on possibly achieved density of such soil is experimentally investigated.A series of laboratory compaction and plate loading tests were carried out on the replaced soil at different fine contents of 0,5,8,10,12 and 15%.The results showed that,the supporting capacity of a replacement soil increases with the increase of its dry density.Therefore,the density of the replacement layer is the major factor controlling its behavior under the effect if external stresses.Compacted sand and gravelly sand are preferred materials when used for soil replacement.They tend to have better engineering properties,if they are placed according to the standard specifications.Another experimental stage of the effect of fines on the bearing capacity of circular footings on gravelly-sand with different percentages of fines was performed.It was found that a fine content of 10%gives the highest dry density,if the soil is compacted according to modified proctor specifications and with the addition of fines,the footing settlement increases and the ultimate bearing carrying capacity decreases.

Method of Growth in Finding the Test Cube of Industrial Robots

In order to find the test cube for industrial robots as specified by ISO 9283, a seed cube is grown up in an irregular working space of the robot, provided that the corners of the cube do not exceed the boundary of the working space. All possible cubes are searched, and the cube with the maximum volume is selected. The calculation examples show that the method of growth can be used for a variety of industrial robots. The method of growth can determine the test cube and test points of irregular working space according to ISO 9283, and can avoid blindness and randomness in the selection of test points.

Numerical simulation on the influence of plant root morphology on shear strength in the sandy soil,Northwest China

Serious riverbank erosion,caused by scouring and soil siltation on the bank slope in the lower reaches of the Tarim River,Northwest China urgently requires a solution.Plant roots play an important role in enhancing soil shear strength on the slopes to maintain slope soils,but the extent of enhancement of soil shear strength by different root distribution patterns is unclear.The study used a combination of indoor experiments and numerical simulation to investigate the effects of varying plant root morphologies on the shear strength of the sandy soil in the Tarim River.The results showed that:(1)by counting the root morphology of dominant vegetation on the bank slope,we summarized the root morphology of dominant vegetation along the coast as vertical,horizontal,and claw type;(2)the shear strength of root-soil composites(RSCs)was significantly higher than that of remolded soil,and the presence of root system made the strain-softening of soil body significantly weakened so that RSCs had better mechanical properties;and(3)compared with the lateral roots,the average particle contact degree of vertical root system was higher,and the transition zone of shear strength was more prominent.Hence,vegetation with vertical root system had the best effect on soil protection and slope fixation.The results of this study have important guiding significance for prevention and control of soil erosion in the Tarim River basin,the restoration of riparian ecosystems,and the planning of water conservancy projects.

Stability and accuracy of central difference method for real-time dynamic substructure testing considering mass participation coefficient

For real-time dynamic substructure testing(RTDST),the influence of the inertia force of fluid specimens on the stability and accuracy of the integration algorithms has never been investigated.Therefore,this study proposes to investigate the stability and accuracy of the central difference method(CDM)for RTDST considering the specimen mass participation coefficient.First,the theory of the CDM for RTDST is presented.Next,the stability and accuracy of the CDM for RTDST considering the specimen mass participation coefficient are investigated.Finally,numerical simulations and experimental tests are conducted for verifying the effectiveness of the method.The study indicates that the stability of the algorithm is affected by the mass participation coefficient of the specimen,and the stability limit first increases and then decreases as the mass participation coefficient increases.In most cases,the mass participation coefficient will increase the stability limit of the algorithm,but in specific circumstances,the algorithm may lose its stability.The stability and accuracy of the CDM considering the mass participation coefficient are verified by numerical simulations and experimental tests on a three-story frame structure with a tuned liquid damper.

Data-driven methods for predicting the representative temperature of bridge cable based on limited measured data

Cable-stayed bridges have been widely used in high-speed railway infrastructure.The accurate determination of cable’s representative temperatures is vital during the intricate processes of design,construction,and maintenance of cable-stayed bridges.However,the representative temperatures of stayed cables are not specified in the existing design codes.To address this issue,this study investigates the distribution of the cable temperature and determinates its representative temperature.First,an experimental investigation,spanning over a period of one year,was carried out near the bridge site to obtain the temperature data.According to the statistical analysis of the measured data,it reveals that the temperature distribution is generally uniform along the cable cross-section without significant temperature gradient.Then,based on the limited data,the Monte Carlo,the gradient boosted regression trees(GBRT),and univariate linear regression(ULR)methods are employed to predict the cable’s representative temperature throughout the service life.These methods effectively overcome the limitations of insufficient monitoring data and accurately predict the representative temperature of the cables.However,each method has its own advantages and limitations in terms of applicability and accuracy.A comprehensive evaluation of the performance of these methods is conducted,and practical recommendations are provided for their application.The proposed methods and representative temperatures provide a good basis for the operation and maintenance of in-service long-span cable-stayed bridges.

Thinking on Improving Presentation Teaching-Based on the Empirical Analysis of Presentation in College English Classes of Junior Non-English Majors in Universities of Science and Engineering

Based on the empirical investigation of presentation in college English classes for junior non-English majors in science and engineering universities,the author explains her own thinking on how to improve presentation teaching from four aspects:setting teaching objectives,selecting teaching contents,using teaching methods,and evaluating and implementing methods.