Scientific Research and Reviews

  • Innovative testing technique of rock stress wave propagation

    Inadequacy of rock mechanics chamber test devices and test systems that cannot accurately simulate gradient static stresses on specimens, this paper presented an innovative testing technique, which relates to the stress wave propagation of rock subjected gradient static stress. The method involves modification of a split Hopkinson pressure bar, such that the test specimen is subjected to gradient static stress and axial impact loading. The device has the features of simple loading and multiple static stress gradients, which verifies the feasibility of stress wave propagation test of red sandstone specimens under linear gradient static stress and conducts stress wave propagation test of red sandstone specimens under linear gradient static stress. Tests on red sandstone specimens with different static stress gradients show that the stress wave propagation of the specimens under gradient static stress is different with their corresponding homogeneous static stress state. The attenuation coefficients of stress waves are different under different conditions, and loading gradient static stress can accelerate the attenuation process. The results of this study will be useful for the analysis of stress wave propagation in deep engineering blasting and the stability analysis of adjacent structures.

  • Determining the location of River Dam Group based on set cover Model: A case study of Zambezi River Basin

    Taking the Zambezi River Basin as a typical case, this paper studied the location problem of dam group. Based on the topographical and elevation maps of the Zambezi River Basin, we evaluated each region by five indicators (Water head difference elevation, Geological environment, Climatic environment, Population distribution and Biodiversity), and selected the 22 candidate dam sites. Meanwhile, the relative feasibility index of dam construction is calculated by the entropy weight-grey correlation analysis. On this basis, combined with the water management capacity of the dam, a set coverage model of dam selection is established, and the neighborhood adaptive particle swarm optimization algorithm (NAPSO) is used to solve the 12 most suitable dam sites. Comparing with the water management capacity of the original Kariba Dam, the new dams’ water storage and flood control capacity, hydroelectric power generation capacity, domestic water supply capacity and other water supply capacity have been increased by 235.92%, 250.62%, 189.66% and 223.61% respectively. Our study can provide some guidance for the site selection project of river dam group.

  • Improved soil plug height calculation formula

    This paper analyzes the soil plugging effect of the open pipe pile during the pile sinking process. The soil in the pipe pile is regarded as a continuous and uninterrupted multiple units, and the force analysis is carried out in the vertical direction, and the vertical balance equation of the soil in the pile is obtained. By establishing an equation, the expression of the plug height of the pipe pile during the pile sinking process is obtained. Comparing the theoretical calculation results with the actual project, it is concluded that the theoretical calculation results can reflect the overall change in the height of the soil plug. Therefore, the pile plug height obtained by calculation has certain guiding significance for the project.

  • The Role Of Acacia Decurrens Tree On Farmers Livelihod In The Banja Woreda

    The aim of the study assesses the role of Acacia Decurrens tree on Farmers Livelihood in the Banja Woreda. To this purpose, the study adopted descriptive survey design. The study focused on the three kebeles such as Zek na Gumerta, Bidana Jegola and kesa Chewsa in the Banaja district of the Awi Zone, Amhara regional state. This design would employ multiple sources of data such as distribution of questionnaires and conducting interviews with the concerned parties. The target population for this study was 25 rural kebeles, from those kebeles I selected three kebeles according to the homogeneity characteristics in plantation of Acacia decurrens tree. To determine the required sample size, the selected kebeles has 678 households’ farmers, 105 sample farmers are represented. Then, 35 sample farmers from each kebeles are selected by random sampling method. One-sample t-test analysis was made using Statistical Package for Social Sciences (SPSS) software version 20 to show the result of study. The result discussed by the use of the descriptive and econometric analysis.

  • Numerical Simulation of Hole Distribution Blasting with Different Distribution Forms

    According to the vibration of cut blasting, the number of holes and the location of holes are reasonably designed by using finite element software LS-DYNA. The rectangular holes and hollow holes in straight cut are simulated respectively. Of the hole in the straight-cut undercut blasting vibration law. The analysis shows that the larger the diameter of the hole is, the better the vibration reduction is. The more the number of holes is, the more obvious the damping effect is. The best blasting effect of the large diameter hollow hole and the large diameter rectangular hole is 0.93cm/s Reduce the blasting vibration speed, buffered the blasting time; get both a good blasting effect and effective rapid damping effect.

  • Forecast of Highway Subgrade Settlement Based on Improved BP Neural Network

    In order to improve the feasibility and accuracy of the roadbed settlement prediction model, the factor analysis method is combined with the BP neural network method, and an improved BP neural network roadbed settlement prediction model is proposed. Select example data to test the improved BP neural network roadbed settlement prediction model. The test results: The relative average error of the 10 sets of training samples’ predicted and actual roadbed settlements was 4.287%, and the roads of five predicted samples The relative error of subgrade settlement is 1.79%, 1.93%, 6.62%, 7.19%, 4.05%, all less than 10%, which proves that the improved BP neural network prediction model has good prediction accuracy.

  • Ship navigation safety risk assessment based on genetic algorithm and BP neural network

    In order to ensure the safe navigation of ships and reduce the occurrence of marine accidents, through the analysis of ship historical navigation safety accident data and related accident literature research, taking into account various aspects such as marine meteorology, cargo loading, ship status and crew quality. Construct a ship navigation safety evaluation body. The BP neural network algorithm is used to design the ship navigation safety risk network structure. The sea damage data is used as the network input sample to train the BP neural network and data fitting. At the same time, the genetic algorithm is introduced to find the individual corresponding to the optimal fitness, and the weight and threshold of the network are further optimized. The purpose is to improve the accuracy of data fitting. The optimized BP neural network evaluation results show that there are many indicators affecting the safety of the ship’s navigation, and the relationship between the indicators is complicated. The optimized BP neural network utilizes the characteristics of online adaptive learning, which eliminates the construction of complex relationships among various indicators within the structure, and solves the difficult problems in ship risk assessment to a certain extent.

  • Application of Reverse Car-seeking in Large Underground Parking Lot Based on A Star Algorithm: A Real Case

    In order to solve the problems of low utilization rate of large parking lots and low efficiency of parking turnover, it is proposed to use A-star algorithm to plan the shortest path for finding a car, and run it in Android system to realize reverse car-searching. By analyzing the current situation of large underground parking lot barriers, A-star algorithm converts the starting point to the destination route into the corresponding parking space to the destination parking space path, calculates the optimal path and provides real-time path car navigation for the vehicle owner. According to the path searched by the A-star algorithm in the Android system, the time spent by the user to blindly search for the vehicle is largely saved, and the parking space utilization rate and the parking turnover rate are effectively improved. Therefore, the research has certain application value in the large parking lots.

  • Nexus between Theory and Practice of Continuous Assessment in Higher Education: Dawa University in Focus

    The final goal of continuous assessment (CA) is to improve the quality of teaching and learning. This study examined the linkage between theoretical assumptions and the real practices of continuous assessment for quality teaching and learning in higher education institutions of Ethiopia, Dire Dawa University in focus. The study employed survey research design. The 73 educators and 289 learners were participated in the study. The study used 5-points Likert scale type data collection instrument. The data were analyzed via SPSS version 20. The data analysis technique employed was a one-sample t-test. The Cronbach’s alpha coefficient was used to test the reliability of instruments and thus, the questionnaires had acceptable alpha coefficients. This study revealed that the instructors and students have acknowledged the opportunities of CA to improve the quality of teaching and learning in HEIs. Finally, if CA is to fit for purpose, the practice of continuous assessment for marking students’ learning performance and for facilitating their further learning should be balanced based on theoretical assumptions. Besides, the need to design competency-based assessment rubric was recommended.

  • Determining Site Location to Find Shortest Path Based on Multi-objective Decision Model

    This paper studies the problem of site selection and tour route, establishes multi-objective decision model and optimizes the line model, uses the Floyd algorithm and uses MATLAB and lingo to program to provide the optimal scheme of site selection and tour route respectively. A single-target optimization model was established, a minimum value function was established for the total distance after weighting, the shortest path length of any two communities was calculated using the Floyd algorithm, and the site of the water and electricity payment was obtained to facilitate residents to pay the utility bill. By establishing the constraint optimization line model, the shortest path of any two residential areas is obtained by The Floyd algorithm, establish the shortest path spanning tree whose root is residential area no.6, and the regions are divided, then optimal tour is obtained.