Search

Copyright of Aero Weaponry is the property of Aero Weaponry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the military net evaluation report published by Rand Corporation, this paper independently explores the combat effectiveness evaluation theory driven by the analytical model of the US military, and studies in detail the analysis and evaluation method of precision guided weapons attacking the airbase in the joint integrated contingency model (JICM), also carries out the deduction and calculation. The results show that the air force aircraft sorties ability is greatly affected by the damage of the airbase, which plays a vital role in the fight for air control. This paper has positive theoretical significance for the in-depth understanding and application of modern combat simulation deduction and evaluation.

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Computer Engineering & Applications is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Computer Engineering & Applications is the property of Beijing Journal of Computer Engineering & Applications Journal Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Remote Sensing is the property of Editorial Office of Journal of Remote Sensing & Science Publishing Co. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To study the stability of the ground during the opening of the rectangular jacking pipe, this paper presented a project of box tunnel in Suzhou, in which a particular case of obstruction clearance was involved. The distribution of the cuttings in the chamber was analyzed and the analytical model for ground stability was established accordingly. Considering the working face was partially supported, the current model was proposed by modifying the traditional silo-wedge model. The residual earth pressure supporting the working face was derived through limit equilibrium analysis. The comparison between the proposed model and traditional model was carried out for verification. The result indicated that the proposed model outperformed the traditional model on ground stability assessing when the width of unsupported area is one-half of the working surface (B/L< 1/2). [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The recharge and discharge of groundwater are mainly vertical surface infiltration recharge, evaporation discharge (evaporation can be shown as negative value of infiltration) and lateral surface water recharge and discharge. One of the most basic problems in hydrogeology is the evaluation criteria of sustainable exploitation of groundwater, which involves the increment of recharge and the decrease of discharge. Therefore, the prediction model of groundwater exploitation must include the above two kinds of recharge and discharge factors, otherwise the evaluation of groundwater cannot meet the requirements. However, the classic Theis unsteady well flow model (1935) only involves the recharge and discharge of the side boundary, and does not considers the surface infiltration recharge of the upper boundary, even when groundwater is pumped near the river. In this way, the analytical model cannot be basically used for prediction, and can only be used for well flow test to obtain the aquifer parameters in dry season. Therefore, the goal of this paper is to develop the Theis unsteady well flow model with surface infiltration recharge. For the problem of phreatic flow, the equation of groundwater flow cannot be established by using head as the dependent variable in a confined aquifer. We use the potential function of the second linearization method to establish groundwater flow equation in the phreatic aquifer. For the solution of the generalized mathematical model of the complex hydrogeological problem with rainfall infiltration and a pumping well, we adopt the method of decomposing it into several simple sub-models and synthesizing them into the solution of the original complex mathematical model. Based on the principle of mass conservation and assuming that the seepage obeys the Darcy’s law and satisfies the Dupuit's assumptions, the differential equation of groundwater flow is established. Then, for the well flow problem with uniform and stable infiltration recharge in two parallel rivers and two kinds of strip regions formed by a river parallel to an impermeable boundary, the general equation of groundwater flow and several kinds of water table equations under specific conditions and their flux equations are obtained. In addition, the “boundary to boundary reflection method” is proposed and applied to solve the same problem in a strip of region between a river boundary in parallel to an impermeable boundary, which reduces many derivation processes. Finally, as a preliminary application of the above theoretical results, it is also an important application, that is, there is a pumping well near the river whose water quality cannot meet the requirements, and the critical flux equation of the pumping well is calculated on the premise of not absorbing the river water. The important and concise relation equation is obtained. The equation can also be used to calculate the critical pumping rate of pumping wells in coastal areas without seawater intrusion. In this paper, the groundwater flow network diagram at a certain time in the process of unstable well flow under the above conditions is given. Compared with the flow network of well flow near the river, which is commonly seen in the literature, the flow network has obvious characteristics.

The accurate description of acoustic emission signals produced by the localized fault of a rolling element bearing plays an important role in its feature extraction and analysis. This paper analyzes the excitation mechanisms and develops the analytical model of acoustic emission signals produced when the rolling element bearing passes across the localized fault on the inner or outer race. Based on the analytical model, the spectral characteristics are discussed substantially. Simulations and experiments are carried out to validate the efficacy of the model developed in the paper. The experimental results show that the response signal thus produced has two parts. The first one is produced by the entry of the rolling element bearing, while the other is produced by the departure of the rolling element bearing. The energy of both parts is concentrated around the resonance frequency of the acoustic emission transducer. Generally, the interval of adjacent acoustic emission events is not equivalent to each other and the corresponding spectrum is continuous in the high frequency band.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The slamming process of two-dimensional structures under free fall condition with arbitrary symmetrical shapes is investigated by combining various analytical models for slamming and the precise integration method in the time domain. By closely analyzing the mathematical expression of analytical models, the total slamming force acting on the body can be decomposed into two terms which are dependent on the velocity and the acceleration respectively. The developed model proposed in this paper is validated against the results from experiments and other numerical methods. Moreover, it is found that if the gravity of body is ignored, which is a reasonable assumption for situations such as structures with light weight or large entry velocity, the maximum acceleration (or the peak slamming force) for a free fall body will always occur at the certain penetration depth for a particular shape and mass, regardless of the initial slamming velocity.

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan University of Science & Technology, Natural Science is the property of Editorial Office of Journal of Henan University of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The backfill mining method is widely used in mines because of its advantages of environmental protection, safety, and efficiency and includes filling slurry pipeline transportation as an important part. The rheological parameters of filling slurry are important indicators for evaluating the characteristics of filling slurry pipeline transport; these parameters are mainly determined by rheometers at present, while the rheological experimental conditions are usually unavailable at the mine site. Because of its simplicity and speed, mines mainly use a slump test to evaluate the flow properties of a filling slurry. In this paper, we used a mini-slump cone to conduct a slump experiment of filling slurry with different mass fractions and cement–tailings ratios (the two most common variable parameters in filling slurry ratios), established an analytical model between the spread of a mini-slump cone and yield stress, obtained a simplified calculation model according to the shape of the filling slurry after flowing, calculated the yield stress of the slurry based on the simplified model, and compared the theoretical value with the experimental value of the yield stress of the filling slurry under the condition of the same ratio tested by a rheometer. At the same time, the influence law of different mass fractions and cement–sand ratios on the expansion degree of the filling slurry was studied using a two-factor analysis of variance. The results show that the spread is mainly influenced by the mass fraction and unsubstantially affected by the cement–sand ratio. The yield stress of the filling slurry increases with the mass fraction. When the mass fraction is low, the error in the theoretical value relative to the experimental value has a large range, and the error in the theoretical value is within 25%, averaging 16.79%; as the mass fraction increases, this error gradually decreases below 15%, averaging 8.81%. Considering its effect, a correction factor based on the mass fraction was proposed, and the error in the theoretical yield stress value after the correction was reduced below 10%, averaging 3.54%. In this study, the mini-slump cone test not only reduces the experimental material and labor intensity compared with the traditional slump test but also effectively characterizes the yield stress of the slurry, which provides practical guidance for evaluating the flowability of mine filling slurry.

The borehole heat exchanger (BHE) is a key component using shallow geothermal energy in ground source heat pump systems (GSHPS), and reasonable pipe spacing design has a great impact on the heat transfer performance and economy of the GSHPs. In most of real applications, the thermal disturbance radius of the maximum heat load per unit length (that is, the most unfavorable case) is often used as the design basis, and this makes it difficult to achieve the technical and economic optimization of the ground source heat pump system. This paper proposes a simple but more practical mathematical method to obtain the thermal disturbance radius of the borehole heat exchanger. The method first derives an analytical solution of the formation temperature distribution around the borehole under the boundary condition of periodic heat flow. On this basis, the actual dynamic building heating and cooling load is approximately expanded into a finite of sine and cosine periodic functions with the Fourier series. By superimposing the analytical solution corresponding to each periodic function obtained by Fourier series expansion of the original dynamic load, the variation of formation temperature distribution under the actual dynamic heating and cooling load conditions can be obtained.

Similarity criteria is the theoretical basis of physical simulation. It is the premise for developing similar materials and determining the condition of experiment. Similarity criteria limits the development of physical simulation test of coal and gas outburst. Because the mechanical model of whole coal and gas outburst process has not been established, the similarity criterion was established using the gas-solid coupling model which could describe the embryonic stage. Similarity criterion above can ensure the deformation and failure law is similar. However,it cannot guarantee the coal and gas outburst phenomenon. This paper presented a method to derive the similarity criteria based on the energy model. A new similarity criterion was derived by similarity transformation. It can ensure that the perimental model is similar to the prototype in energy concentration, transfer and release. Combined the two groups of similarity criterion, on the basis of the similarity of the energy model and coal deformation and failure,a new similarity criteria of physical simulation on coal and gas outburst was established. Compared with the previous physical simulation results, it is proved that the similarity criterion is reasonable. [ABSTRACT FROM AUTHOR]

In order to study the force variation of the drill bit in the dynamic process of rock drilling deeply, systematical dynamics analysis was presented in the paper. Differential equations which described the force fluctuations in the process of rock drilling were established and various factors which affect the force fluctuations of the drill bit were also analyzed. Based on the analysis of the process of movement in rock drilling, analytical method for force computation of the drill bit in the dynamic process was given. Analytical calculation model of penetrating force and cutting force in the dynamic process was derived respectively. Studies show that the force of drill bit is closely related to its motion state; the average penetrating force and cutting force in the dynamic process increase with the increasing of penetration speed V in the case of the other conditions remain unchanged. Calculation results show that the analytical dynamic model is more precise than the traditional method of static calculation model compared with experimental measurements, and more conducive to be a intuitive and laconic guidance in engineering practice. [ABSTRACT FROM AUTHOR]

Active fault is a major geological hazard threat to submarine pipelines, which may subject to excessive axial deformation and fail from the faulting. Thus an improved analytical method for strain of submarine pipeline under strike-slip faulting was proposed in this paper. The nonlinear constitutive relation of pipeline materials was considered based on the linear strengthening model, and the influence of soil nonlinear constraint on the response of the pipe structure was accurately calculated through the nonlinear soil spring model with ideal elastic-plastic constitutive relation. From the differential control equation of the pipeline stress, analytical results of the axial strain in the pipeline were derived and the expression of the pipe elongation was obtained. Based on the equilibrium equation and iterative calculation, the stress and strain of the pipeline can finally be accurately calculated. Compared with the finite element calculation results, the improved analytical method for pipe strain has higher calculation accuracy than the existing recommended method (i.e. Newmark method).