Using deep neural networks coupled with principal component analysis for ore production forecasting at open-pit mines

Ore production is usually affected by multiple influencing inputs at open-pit mines.Nevertheless,the complex nonlinear relationships between these inputs and ore production remain unclear.This becomes even more challenging when training data(e.g.truck haulage information and weather conditions)are massive.In machine learning(ML)algorithms,deep neural network(DNN)is a superior method for processing nonlinear and massive data by adjusting the amount of neurons and hidden layers.This study adopted DNN to forecast ore production using truck haulage information and weather conditions at open-pit mines as training data.Before the prediction models were built,principal component analysis(PCA)was employed to reduce the data dimensionality and eliminate the multicollinearity among highly correlated input variables.To verify the superiority of DNN,three ANNs containing only one hidden layer and six traditional ML models were established as benchmark models.The DNN model with multiple hidden layers performed better than the ANN models with a single hidden layer.The DNN model outperformed the extensively applied benchmark models in predicting ore production.This can provide engineers and researchers with an accurate method to forecast ore production,which helps make sound budgetary decisions and mine planning at open-pit mines.

Development of a DFN-based probabilistic block theory approach for bench face angle design in open pit mining

In open pit mining,uncontrolled block instabilities have serious social,economic and regulatory consequences,such as casualties,disruption of operation and increased regulation difficulties.For this reason,bench face angle,as one of the controlling parameters associated with block instabilities,should be carefully designed for sustainable mining.This study introduces a discrete fracture network(DFN)-based probabilistic block theory approach for the fast design of the bench face angle.A major advantage is the explicit incorporation of discontinuity size and spatial distribution in the procedure of key blocks testing.The proposed approach was applied to a granite mine in China.First,DFN models were generated from a multi-step modeling procedure to simulate the complex structural characteristics of pit slopes.Then,a modified key blocks searching method was applied to the slope faces modeled,and a cumulative probability of failure was obtained for each sector.Finally,a bench face angle was determined commensurate with an acceptable risk level of stability.The simulation results have shown that the number of hazardous traces exposed on the slope face can be significantly reduced when the suggested bench face angle is adopted,indicating an extremely low risk of uncontrolled block instabilities.

Solution to the Horizontal Crossing Problem of Transportation System at Key Points in Open-Pit Mines

In order to reduce the horizontal crossing transportation problems between coal trucks and stripping trucks,large and small vehicles,and transport trucks and belt conveyors at key points of open pit mine in production,the separate transportation mode of underpass bridge and overpass steel trestle is proposed to optimize the open pit development transportation system,so as to solve the practical problems that the horizontal cross of transport vehicles causes vehicle blockage,affects production schedule and production safety.The results show that the horizontal crossing road can be changed into a separate type of overpass steel trestle,which can realize the classified transportation of large and small vehicles,reduce the traffic density,make vehicles with different functions go their own way,eliminate the hidden danger of traffic accidents,and improve the production efficiency.

A Comparative Study of Two Tree-Based Models for Predicting Flyrock Velocity at Open Pit Bench Mining

Blasting is a cost-effective technique to break hard rock volumes by using explosives in the mining and civil engineering realms. Moreover, although blasting is a designed process and plays an indispensable role in these industries, it can also have multiple adverse environmental impacts. One such effect is flyrock, which poses risks to nearby machinery, and residential structures, and can even lead to injuries or fatalities. To optimize blasting efficiency as well as restrict side effects, prediction of the blast aftereffects is vital. Therefore, the present work focuses on using two machine learning methods to predict the velocity of flyrock in the open pit mine. To address this issue, a comprehensive dataset was gathered from the open pit mine. Then, Decision Tree and Random Forest algorithms were employed to predict flyrock velocity. The Random Forest model demonstrated superior performance compared to the Decision Tree model. Nonetheless, the performance of the Decision Tree model was deemed satisfactory, as evidenced by its coefficient of determination value of 0.83, mean squared error (MSE) of 4.2, and mean absolute percentage error (MAPE) of 5.6%. Considering these metrics, it is reasonable to conclude that tree-based algorithms can be effective in predicting flyrock velocity.

基于虚拟仿真的爆破工程实践教学探索

为了解决《爆破工程》实践教学中存在的爆炸安全隐患、火工品管控、储运条件严苛、教学场地狭小等问题,从教学方案设计、教学资源收集、虚拟仿真实现、教学应用与考查四个方面,构建了包含隧道掘进爆破与台阶爆破的虚拟仿真实验平台,探索出一套适用于华北科技学院城市地下空间工程专业的《爆破工程》实践教学模式。实际应用表明,虚拟仿真教学在激发学习兴趣、培养自主应用、增强实践能力等方面成效显著,极大提升了学生对知识的实际应用能力。

Gas Bench Ⅱ-IRMS磷酸法在线测定水中溶解无机碳碳同位素分析条件及影响因素

采用Gas Bench Ⅱ-IRMS对水中溶解无机碳碳同位素在线测定影响因素进行研究,确立了分析方法。通过对影响因素的研究确定了水中溶解无机碳碳同位素测试的最佳平衡时间;样品水中溶解无机碳浓度与样品测试的信号强度呈明显正相关;测试过程中色谱柱温度的高低不仅会影响样品峰的出峰时间,还会影响样品峰宽、峰高及峰积分面积等,影响最终测试结果。为了确保水中溶解无机碳碳同位素测试方法的准确性与可行性,进行了方法试验验证,水中溶解无机碳碳同位素比值(δ^(13)C)的测定值与验证单位给出的δ^(13)C测定值相一致,此测试方法具有可行性。在线测试的高效率和小样量与传统方法比较有显著优势,这为拓展同位素分析技术的应用领域提供了一种快速、高效的手段。本测试分析方法适用于地下水、地表水、大气降水的溶解无机碳碳同位素组成的在线测定。

Gas Bench Ⅱ-IRMS测定地下水中溴同位素新技术

建立了利用Gas Bench Ⅱ联用同位素比值质谱仪(Gas Bench Ⅱ-IRMS)用于测定地下水中溴稳定同位素的方法。基于溴比氯更容易被重铬酸钾氧化的性质,将Br-氧化成Br2,而氯残留在原溶液中,从而把溴与氯分离开;再利用AgNO3将溴以AgBr的形式沉淀下来,然后将AgBr转化成CH3Br进行溴稳定同位素质谱测定。反应中,CH3I用量为20μL,AgBr用量为0.5mg。本测试流程需溴4～10mg,质谱测试时间由1.5h缩短为800s,测试精度优于±0.1‰(2σ)。该方法可以用于地下水中溴同位素测定,在水文地质研究中具有广阔的应用前景。

Optimization model of GNSS/pseudolites structure design for open-pit mine positioning

A new pseudolites （PLs） structure optimization model of global navigation satellite system （GNSS）/PLs integration positioning system used in deep open-pit mine was presented. Position dilution of precision （Pdop） and reliability were selected as the optimization indicators to build a multi-objective optimization model to decide the optimum PLs location. A scheme was designed by establishing a four-dimensional model taking azimuth （a）, elevation angle （e） and epoch （t） of satellites as the input independent variables and Pdop as the dependent variable to calculate the optimum PLs location zone considering the real circumstances. And then the ultimate PLs location can be fixed by testing the curves of Pdop along time. A field collected Trimble R8 GPS data set in China University of Mining and Technology （CUMT） campus was used for the model test to show the effectiveness, and the proposed PLs optimum design scheme was used at the west open-pit mine of Fushun mining group Co., Ltd., in China, better Pdop and reliability have been achieved for the integration system. Both experiments show that the proposed scheme is excellent in designing GNSS/PLs system which is helpful for improving the performance of the positioning system and reducing the cost.

Modified algorithm of combined GPS/GLONASS precise point positioning for applications in open-pit mines

A modified algorithm of combined GPS/GLONASS precise point positioning （GG-PPP） was developed by decreasing the number of unknowns to be estimated so that accurate position solutions can be achieved in the case of less number of visible satellites. The system time difference between GPS and GLONASS （STDGG） and zenith tropospheric delay （ZTD） values were firstly estimated in an open sky condition using the traditional GG-PPP algorithm. Then, they were used as a priori known values in the modified algorithm instead of estimating them as unknowns. The proposed algorithm was tested using observations collected at BJFS station in a simulated open-pit mine environment. The results show that the position filter converges much faster to a stable value in all three coordinate components using the modified algorithm than using the traditional algorithm. The modified algorithm achieves higher positioning accuracy as well. The accuracy improvement in the horizontal direction and vertical direction reaches 69% and 95% at a satellite elevation mask angle of 50°, respectively.

Failure characteristics and its influencing factors of talus-derived rock mass during open-pit mining

The failure characteristic of talus-derived rock mass continues to challenge quantitative hazard assessments in open-pit mining. Physical model test was used to assess the failure modes and mechanisms on talus-derived rock mass. The different types of failure modes of the talus-derived rock mass were introduced and a possible failure mechanism relation between the failure zone and the structure of the talus-derived rock mass was also shown. The physical model test results indicate that the rainfall has significant influence on the stability and failure modes of talus-derived rock mass during open-pit mining. The development of the seepage area caused by rainfall initiates the localized failure in that particular area, and the initiation of localized instability is mainly induced by stress changes concentrated in the seepage area.

基于Workbench的青核桃力学特性分析

根据青核桃去皮过程中的受力特点,分析青核桃静力学特性,建立青核桃的几何模型;通过对青核桃进行不同加载方式下的压力试验,运用Workbench对青核桃在不同加载方式下的力学特性进行仿真模拟。通过比较压力试验和模拟仿真值,发现二者的结果一致,说明仿真的可行性,所建的力学模型可以分析核桃青皮在去皮过程的破损机理,可为研制新型青核桃去皮机械提供参考依据。压力试验与有限元模拟结果表明,施加相同压力条件下,方向并不是去青皮的决定性因素。

基于Workbench的缩套式超高压缸体优化设计

某设备的缩套式超高压缸体存在内壁始终为应力最大位置,且缸体应力分布相当不均匀的问题。为满足缸体最大等效应力小于缸体材料的屈服极限,以内外缸体内壁剪应力相等为约束条件,结合过盈配合及设计要求,利用响应面法对缩套式超高压缸体进行优化设计。结果表明,缸体的过盈量从优化前的0.30 mm减小到优化后的0.2662 mm,降低了内外缸安装套合时的工作难度;内缸内壁到外缸内壁的等效应力的变化率从优化前的0.787 MPa/mm降为0.0568 MPa/mm,缸体的应力分布不均匀性较优化前有了较大的改观。

基于ANSYS Workbench的结构应力分析的子模型法

提出了在ANSYS Workbench中使用子模型的一种新方法。首先创建一个包含远端区,过渡区和子模型区的几何模型;然后对此几何模型进行分析得到粗糙模型的结果,并把过渡区的节点位移导出;整理导出结果形成ANSYS APDL命令;最后基于过渡区和子模型区得到子模型,在子模型中加载命令流从而形成新的边界条件,通过对子模型区的反复细化从而得到问题的收敛解。使用ANSYS中的一个算例进行考察,并与经典方法进行比较,结果表明:该方法具有很高的精度,计算结果正确,且操作简易,适合在复杂零件仿真中使用。

露天矿富水裂隙岩体台阶爆破的殉爆机理和防殉爆研究

殉爆现象会影响露天矿台阶爆破作业安全、边坡稳定性和爆破效果。在炸药冲击起爆机理基础上,并结合露天矿实际富水裂隙岩体台阶爆破振动监测结果,通过对比爆破振动信号波动差异来判别殉爆现象。为研究殉爆产生的机理和防殉爆方法,采用数值模拟和现场试验分析主发药量、裂隙宽度及药包之间的距离等参数对被发药包孔壁压力的影响。结果表明:孔壁冲击压力随着装药耦合系数的减小、炮孔间裂隙宽度(0.25~1.00 cm)的增大以及炮孔间距离的减小而提高。在裂隙位置装药使用阻波管、充填岩粉或设置空气间隔器,能显著降低通过富水裂隙传递到被发炮孔的冲击压力,并使其低于乳化炸药的起爆压力临界值。当炮孔内只有单条裂隙时,选择填充岩粉是便捷且有效防殉爆方法;当炮孔内有多条裂隙时,该试验条件下,炮孔内放置厚度为2.6 mm的阻波管是最佳防殉爆方法,并能保证爆破效果。

Electronics Workbench——“计算机里的电子实验室”

文章介绍了EWB充当电子实验室虚拟试验平台所具有的重要意义,并通过其在电工、数字电子技术、模拟电子技术实验中的相关应用,举例对上述观点加以验证。

Sizing of rock fragmentation modeling due to bench blasting using adaptive neuro-fuzzy inference system(ANFIS)

One of the most important characters of blasting,a basic step of surface mining,is rock fragmentation because it directly effects on the costs of drilling and economics of the subsequent operations of loading,hauling and crushing in mines.Adaptive neuro-fuzzy inference system(ANFIS)and radial basis function(RBF)show potentials for modeling the behavior of complex nonlinear processes such as those involved in fragmentation due to blasting of rocks.We developed ANFIS and RBF methods for modeling of sizing of rock fragmentation due to bench blasting by estimation of 80%passing size(K_(80))of Golgohar iron mine of Sirjan.Iran.Comparing the results of ANFIS and RBF models shows that although the statistical parameters RBF model is acceptable but ANFIS proposed model is superior and also simpler because ANFIS model is constructed using only two input parameters while seven input parameters used for construction of RBF model.

High precision slope deformation monitoring model based on the GPS/Pseudolites technology in open-pit mine

As the number and geometric intensity of visual satellites are susceptible to large slopes in open-pit mines, we propose integration of GPS/Pseudolites (PLs) positioning technology which can increase the number of visible satellites, strengthen the geometric intensity of satellites and provide a precision solution for slope deformation monitoring. However, the un-modeled systematic errors are still the main limiting factors for high precision baseline solution. In order to eliminate the un-modeled systematic error, the Empirical Mode Decomposition (EMD) theory is employed. The multi-scale decomposition and reconstruction architecture are defined here on the basis of the EMD theory and the systematic error mitigation model is demonstrated as well. A standard of the scale selection for the systematic error elimination is given in terms of the mean of the accumulated standardized modes. Thereafter, the scheme of the GPS/PLs baseline solution based on the EMD is suggested. The simulation and experiment results show that the precision factors (DOP) are reduced greatly when PLs is located suitably. The proposed scheme dramatically improves the reliability of ambiguity resolution and the precision of baseline vector after systematic error being eliminated, and provides an effective model for high precision slope deformation monitoring in open-pit mine.

Inertia Matching During Dynamic Simulation of Vehicle Drive System on Test Bench

Framework and basic parameters of a test bench for motor drive system of electric vehicle (EV) are illuminated. Two kinds of electric drive models, one was for the electric vehicle drived on real road, the other was for that on test bench, are put forward. Then, dynamic analysis of these models is made in detail. Inertia matching method of the test bench is researched and some useful formulas and graphs are brought forward. The experiment of an electric bus is introduced in order to explain the usage of this inertia matching method.

Dynamic phase-mining optimization in open-pit metal mines

Three important aspects of phase-mining must be optimized:the number of phases,the geometry and location of each phase-pit(including the ultimate pit),and the ore and waste quantities to be mined in each phase.A model is presented,in which a sequence of geologically optimum pits is first generated and then dynamically evaluated to simultaneously optimize the above three aspects,with the objective of maximizing the overall net present value.In this model,the dynamic nature of the problem is fully taken into account with respect to both time and space,and is robust in accommodating different pit wall slopes and different bench heights.The model is applied to a large deposit consisting of 2044 224 blocks and proved to be both efficient and practical.

Low-Load Bench Press Training to Fatigue Results in Muscle Hypertrophy Similar to High-Load Bench Press Training

The purpose of this study was to determine whether the training responses observed with low-load resistance exercise to volitional fatigue translates into significant muscle hypertrophy, and compare that response to high-load resistance training. Nine previously untrained men (aged 25 [SD 3] years at the beginning of the study, standing height 1.73 [SD 0.07] m, body mass 68.9 [SD 8.1] kg) completed 6-week of high load-resistance training (HL-RT) (75% of one repeti-tion maximal [1RM], 3-sets, 3x/wk) followed by 12 months of detraining. Following this, subjects completed 6 weeks of low load-resistance training (LL-RT) to volitional fatigue (30% 1 RM, 4 sets, 3x/wk). Increases (p 0.05) in magnetic resonance imaging-measured triceps brachii and pectorals major muscle cross-sectional areas were similar for both HL-RT (11.9% and 17.6%, respectively) and LL-RT (9.8% and 21.1%, respectively). In addition, both groups increased (p 0.05) 1RM and maximal elbow extension strength following training;however, the percent increases in 1RM (8.6% vs. 21.0%) and elbow extension strength (6.5% vs. 13.9%) were significantly (p 0.05) lower with LL-RT. Both protocols elicited similar increases in muscle cross-sectional area, however differences were observed in strength. An explanation of the smaller relative increases in strength may be due to the fact that detraining after HL-RT did not cause strength values to return to baseline levels thereby producing smaller changes in strength. In addition, the results may also suggest that the consistent practice of lifting a heavy load is necessary to maximize gains in muscular strength of the trained movement. These results demonstrate that significant muscle hypertrophy can occur without high-load resistance training and suggests that the focus on percentage of external load as the important deciding factor on muscle hypertrophy is too simplistic and inappropriate.