Using stress analysis theory and method, rocky crushing mechanism between two holes of single line hole simultaneity explosion is studied. Analysing the distribution of rocky tension pressure region, pressure region, pure tension surface in the range of two holes explosion and the elastic displacement region's stress, strain and movement state during explosion, it is considered that during the precrack explosion, big hole distance and other single line hole simultaneity explosion, the penetration between two holes is identical, the penetration is not accomplished only by the tension vertical to the gun port center on line, and all factors that make rock to form the deformation and displacement facing the free surface affect the penetration between two holes.
To determine the effects of Ti and mixing entropy (ΔSmix) on the structure and mechanical proper-ties of Zr-Ta alloys and then find a new potential energetic structural material with good me-chanical properties and more reactive elements, TixZr2.5-xTa (x = 0, 0.5, 1.0, 1.5, 2.0) alloys were investigated. The XRD experimental results showed that the phase transformation of TixZr2.5-xTa nonequal-ratio ternary alloys depended not on the value of ΔSmix, but on the amount of Ti atoms. With the addition of Ti, the content of the HCP phase decreased gradually. SEM analyses revealed that dendrite morphology and component segregation increasingly developed and then weakened gradually. When x increases to 2.0, TixZr2.5-xTa with the best mechanical properties can be ob-tained. The yield strength, compressive strength and fracture strain of Ti2.0Zr0.5Ta reached 883 MPa, 1568 MPa and 34.58%, respectively. The dependence of the phase transformation and me-chanical properties confirms that improving the properties of Zr-Ta alloys by doping Ti is feasible.
Precast segmental concrete beams (PSCBs) are being increasingly applied in bridges worldwide benefitting from the advantages of accelerated bridge construction. It is of importance to accurately predict the direct shear strength (DSS) of precast concrete joints (PCJs) for ensuring the safe structural design of PSCBs. However, existing prediction models of PCJs' DSS are deemed inaccurate and unreliable when numerous parameters are varied in wide ranges. This study aims to establish an accurate and reliable prediction model for PCJs' DSS using a machine learning algorithm called support vector regression (SVR). A PCJs' DSS database of 304 test results with 23 input parameters was assembled from the literature. A model training procedure was conducted through stratified train-test split, feature scaling, feature selection, and two-step grid-search hyperparameter tuning. A new correlation matrix–based feature selection method was proposed, and three SVR models with different feature combinations were trained for validating the selection method. The trained SVR models were experimentally validated and compared with six existing mechanical models through two groups of performance indicators. A reasonable interpretation for the SVR model with the selected features in the proposed selection method was done using the combination of partial dependence (PD) and individual conditional expectation (ICE) plots. The results show that the SVR algorithm can be deemed feasible to accurately and reliably predict the DSS of PCJs. The proposed feature selection method is beneficial to the prediction performance of the SVR model. It is impossible for the typical mechanical models to achieve a similar prediction performance of the SVR model. The influence of each input parameter on the DSS of PCJs is recognized and depicted, which can offer useful information for further developing new mechanical models for predicting the DSS of PCJs with higher prediction performance in future research.
With the increasing scale of power cables, the lack of reliable and stable power supply for cable monitoring sensors with light load and weak magnetic field has become a key problem, and restricting the development of the Internet of Things for power transmission and distribution. This paper first analyzes the current power supply technology of cable monitoring sensors, and through the analysis of the single core cable structure and its magnetic field influencing factors, proposes a scheme for power supply of weak magnetic field cable monitoring sensors. Combined with the magnetic field energy extraction output model, a self-energy extraction device for the weak magnetic field cable environment is developed. Through the test verification, the device can complete the stable power supply of the light load cable monitoring sensor.
A key problem of high-velocity concave flow through the invert of spillways is the potential of cavitation damage at the flow surface.The flow over the invert of No.1 spillway tunnel in Baihetan Hydropower Station was studied by numerical simulation.The k-e turbulence model is applied to carry out the numerical simulation.The hydraulic and cavitation properties of the vertical curve flow are obtained.It is found that the piezometric pressure with concave flow increases along the anti-arc segment and reaches the maximum value at the end of the invert.The shear stress also increases along the invert and extends to some distance along the slope downstream.The cavitation index decreases along the vertical curve,so the aerators must be applied successfully in the spillway tunnel.And the sufficient quantities of air should be entrained into the water nearby the lower parts of the sidewalls and the bottom surface downstream of the invert.
This paper proposes a method to reduce the oil leakage of the hydrostatic slide table. The method reduces the friction loss of the oil cavity through structural optimization, and derives the optimal ratio of the length and width of the oil cavity sealing oil edge in the oil cavity size. The clearance seal design is added around the down-pressing board, and the advantage of the extremely small thickness of the oil film is combined with an appropriate edge width and an oil-saving groove to ultimately reduce the leakage of oil. The theoretical calculations show that this method can better solve the oil in the down-pressing board problems with leaks.
With the core description of the evaluation,the CMM rank has become the standard of software enterprise competition.With the current existence question explanation of our country software development enterprise,the paper elaborates software enterprise in our country must rapidly develop and move towards the world.It also describe the way that must be taken as well as the questions which CMM should pay attention to,and separately carried on the analysis to the CMM rank and the system design.
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