Prediction of a maximum pull-out load of anchor bolts using an optimal combination model

The mixed model of improved exponential and power function and unequal interval gray GM(1,1)model have poor accuracy in predicting the maximum pull-out load of anchor bolts.An optimal combination model was derived using the optimally weighted combination theory and the minimum sum of logarithmic squared errors as the objective function.Two typical anchor bolt pull-out engineering cases were selected to compare the performance of the proposed model with those of existing ones.Results showed that the optimal combination model was suitable not only for the slow P-s curve but also for the steep P-s curve.Its accuracy and stable reliability,as well as its prediction capability classification,were better than those of the other prediction models.Therefore,the optimal combination model is an effective processing method for predicting the maximum pull-out load of anchor bolts according to measured data.

Effects of different pull-out loading rates on mechanical behaviors and acoustic emission responses of fully grouted bolts

Due to the influence of mining disturbance stress,it is of great significance to better understand the bearing characteristics of fully grouted bolts under different pull-out loading rates.For this purpose,a series of laboratory pull-out tests were conducted to comprehensively investigate the effects of different pull-out loading rates on the mechanical performance and failure characteristics of fully grouted bolts.The results show that the mechanical performance of the anchored specimen presents obvious loading rate dependence and shear enhancement characteristics.With the increase of the pull-out loading rates,the maximum pull-out load increases,the displacement and time corresponding to the maximum pull-out load decrease.The accumulated acoustic emission(AE)counts,AE energy and AE events all decrease with the increase of the pull-out loading rates.The AE peak frequency has obvious divisional distribution characteristics and the amplitude is mainly distributed between 50-80 dB.With the increase of the pull-out loading rates,the local strain of the anchoring interface increases and the failure of the anchoring interface transfers to the interior of the resin grout.The accumulated AE counts are used to evaluate the damage parameter of the anchoring interface during the whole pull-out process.The analytical results are in good agreement with the experimental results.The research results may provide guidance for the support design and performance monitoring of fully grouted bolts.

Estimation of the Maximum Annual Loads Modeling for Kingdom of Bahrain

The present paper proposes the impact of the air temperature on electricity demand as expected. It is clear that the annual maximum load is recorded versus the years starting by the year 2009 up to 2012. At present, the graph fitting technique is applied with some mathematical and computational tools based on the actual values of the years 2009 up to 2012 considering the lower values, the higher values and the average values of the annual maximum loads for Kingdom of Bahrain. For the three scenarios, the models are obtained by curve fitting technique. As well, the model of actual loads is obtained finally which has mostly the closest values obtained.

Variable Parameter Nonlinear Control for Maximum Power Point Tracking Considering Mitigation of Drive-train Load

Since mechanical loads exert a significant influence on the life span of wind turbines, the reduction of transient load on drive-train shaft has received more attention when implementing a maximum power point tracking U+0028 MPPT U+0029 controller. Moreover, a trade-off between the efficiency of wind energy extraction and the load level of drive-train shaft becomes a key issue. However, for the existing control strategies based on nonlinear model of wind turbines, the MPPT efficiencies are improved at the cost of the intensive fluctuation of generator torque and significant increase of transient load on drive train shaft. Hence, in this paper, a nonlinear controller with variable parameter is proposed for improving MPPT efficiency and mitigating transient load on drive-train simultaneously. Then, simulations on FAST U+0028 Fatigue, Aerodynamics, Structures, and Turbulence U+0029 code and experiments on the wind turbine simulator U+0028 WTS U+0029 based test bench are presented to verify the efficiency improvement of the proposed control strategy with less cost of drive-train load. © 2017 Chinese Association of Automation.

Hybrid Deep Learning Architecture to Forecast Maximum Load Duration Using Time-of-Use Pricing Plans

Load forecasting has received crucial research attention to reduce peak load and contribute to the stability of power grid using machine learning or deep learning models.Especially,we need the adequate model to forecast the maximum load duration based on time-of-use,which is the electricity usage fare policy in order to achieve the goals such as peak load reduction in a power grid.However,the existing single machine learning or deep learning forecasting cannot easily avoid overfitting.Moreover,a majority of the ensemble or hybrid models do not achieve optimal results for forecasting the maximum load duration based on time-of-use.To overcome these limitations,we propose a hybrid deep learning architecture to forecast maximum load duration based on time-of-use.Experimental results indicate that this architecture could achieve the highest average of recall and accuracy(83.43%)compared to benchmark models.To verify the effectiveness of the architecture,another experimental result shows that energy storage system(ESS)scheme in accordance with the forecast results of the proposed model(LSTM-MATO)in the architecture could provide peak load cost savings of 17,535,700 KRW each year comparing with original peak load costs without the method.Therefore,the proposed architecture could be utilized for practical applications such as peak load reduction in the grid.

Total Maximum Allocated Loads on Stoichiometry of Nitrogen and Identification of Critical Form in Jiaozhou Bay, China

Total pollutant load control management for total dissolved nitrogen(TDN) is an urgent task required to gain a good water quality status in Jiaozhou Bay(JZB), China. In this paper, the stoichiometry of multiform TDN on land-ocean interactions associated with marine biogeochemical reaction(LOIMBR) was studied by modeling the load-response relationship based on a three-dimensional water quality model of nitrogen in JZB. The results showed that the stoichiometry on LOIMBR of dissolved organic nitrogen(DON), NO3-N and NH4-N was 3:1:1, with one-third of the contribution on the concentration of dissolved inorganic nitrogen(DIN) in JZB for the land-based DON loads to DIN loads. Based on the stoichiometric relationship of nitrogen forms, the total maximum allocated load(TMAL) of equivalent TDN(ETDN) was approximately 5300 t a^-1 in JZB, equivalent to the TMAL of 5700, 5800 and 15600 t a^-1 for NH4-N, NO3-N and DON, respectively. According to the loads of ETDN, there were four outfalls overloaded in JZB in 2015, which lie in the head of the bay. In the four overloaded outfalls, besides NO3-N, NH4-N was the critical nitrogen control form for Moshui River, while DON for Dagu River and Haibo River. The results of numerical experiments further showed that JZB will achieve good water quality after 7 years by implementation of the 'different emission reduction' based on TMAL of ETDN, which is significantly better than 'equal percent removal'.

Annual Maximum Loads Estimation Modeling for Kingdom of Bahrain

The present paper proposes the impact of the air temperature on electricity demand as expected. The annual maximum load is recorded versus the years starting by the year 2009. At present, the graph fitting was applied with some mathematical and computational tools considering the lower values, the higher values and the average values of the annual maximum loads of Kingdom of Bahrain. For the three scenarios, the models are obtained by curve fitting technique. As well, the model of actual loads is obtained finally which has mostly the closest values obtained.

Maximum Force of Inclined Pullout of A Torpedo Anchor in Cohesive Beds

Torpedo anchors have been used in mooring systems for deep-water oil and gas projects owing to their prominent advantages, such as low cost and easy installation. The maximum force of torpedo anchors is crucial not only to the safety and stability of vessels and other marine facilities, but also for an economical design. It is necessary to develop reliable formula for fast predicting their maximum inclined force of a torpedo anchor in cohesive beds. In this study, the maximum inclined force of a torpedo anchor vertically embedded in cohesive beds was extensively investigated. 316 sets of inclined pullout laboratory tests were carried out for 9 differently shaped torpedo anchors which were vertically embedded in different cohesive beds. The loading curves were automatically acquisitioned and their characteristics were analyzed. The load angle relative to the horizontal varied from 20° to 90°. A new formula for fast calculating the maximum inclined force of the torpedo anchor vertically embedded in cohesive beds was obtained based on force analysis and a nonlinear regression on the data from the present and other studies. Effect aspects on the tests are discussed and further studies are highlighted.

A hardening load transfer function for rock bolts and its calibration using distributed fiber optic sensing

Confinement of rock bolts by the surrounding rock formation has long been recognized as a positive contributor to the pull-out behavior,yet only a few experimental works and analytical models have been reported,most of which are based on the global rock bolt response evaluated in pull-out tests.This paper presents a laboratory experimental setup aiming to capture the rock formation effect,while using distributed fiber optic sensing to quantify the effect of the confinement and the reinforcement pull-out behavior on a more local level.It is shown that the behavior along the sample itself varies,with certain points exhibiting stress drops with crack formation.Some edge effects related to the kinematic freedom of the grout to dilate are also observed.Regardless,it was found that the mid-level response is quite similar to the average response along the sample.The ability to characterize the variation of the response along the sample is one of the many advantages high-resolution fiber optic sensing allows in such investigations.The paper also offers a plasticity-based hardening load transfer function,representing a"slice"of the anchor.The paper describes in detail the development of the model and the calibration/determination of its parameters.The suggested model captures well the coupled behavior in which the pull-out process leads to an increase in the confining stress due to dilative behavior.

Maximum tolerated volume in drinking tests with water and a nutritional beverage for the diagnosis of functional dyspepsia

AIM: Recently, drinking load tests with water or nutritional beverages have been proposed as diagnostic tools for functional dyspepsia (FD), therefore we sought to reproduce if these tests can discriminate between FD patients and controls in a Mexican population. METHODS: Twenty FD-Rome Ⅱ patients were matched by age and gender with 20 healthy controls. All underwent both drinking tests at a 15 mL/min rate, randomly, 7 d apart. Every 5 min within each test, four symptoms were evaluated (satiety, bloating, nausea and pain) by Likert scales. Maximum tolerated volume (MTV) was defined as the ingested volume when a score of 5 was reached for any symptom or when the test had to be stopped because the patients could not tolerate more volume. Sensitivity and specificity were analyzed. RESULTS: FD patients had higher symptom scores for both tests compared to controls (water: t= 4.1, P= 0.001 ＜0.01; Nutren(R): t= 5.2, P= 0.001＜0.01). The MTV forwater and Nutren(R) were significantly lower in FD (water: 1014±288 vs 1749±275 mL; t = 7.9, P = 0.001＜0.01;Nutren(R): 652±168 vs 1278±286 mL; t= 6.7, P = 0.001＜0.01). With the volume tolerated by the controls, the percentile 10 was determined as the lower limit fortolerance. Sensitivity and specificity were 0.90, 0.95 for water and 0.95, 0.95 for Nutren(R) tests.CONCLUSION: A drinking test with water or a nutritional beverage can discriminate between FD patients and healthy subjects in Mexico, with high sensitivity and specificity. These tests could be used as objective, noninvasive, and safe diagnostic approaches for FD patients.

Experimental and numerical evaluation on debonding of fully grouted rockbolt under pull‑out loading

The axial loading in rockbolts changes due to stress redistribution and rheology in the country rock mass.Such a change may lead to debonding at rockbolt to grout interface or rupture of the rockbolt.In this study,based on laboratory experiments,ultrasonic guided wave propagation in fully grouted rockbolt under different pull-out loads was investigated in order to examine the resultant debonding of rockbolt.The signals obtained from the ultrasonic monitoring during the pull-out test were processed using wavelet multi-scale analysis and frequency spectrum analysis,the signal amplitude and the amplitude ratio(Q)of low frequency to high frequency were defined to quantify the debonding of rockbolt.In addition to the laboratory test,numerical simulation on the effect of the embedment lengths on ultrasonic guided wave propagation in rockbolt was conducted by using a damage-based model,and the debonding between rockbolt and cement mortar was numerically examined.It was confirmed that the ultrasonic guided wave propagation in rockbolt was very sensitive to the debonding because of pull-out load,therefore,the critical bond length could be calculated based on the propagation of guided wave in the grouted rockbolt.In time domain,the signal amplitude in rockbolt increased with pull-out load from 0 to 100 kN until the completely debonding,thus quantifying the debonding under the different pull-out loads.In the frequency domain,as the Q value increased,the debonding length of rockbolt decreased exponentially.The numerical results confirmed that the guided wave propagation in the fully grouted rockbolt was effective in detecting and quantifying the debonding of rockbolt under pull-out load.

Peak Load Modeling for Kingdom of Bahrain

Deriving some models to estimate the electrical demand for future for the Kingdom of Bahrain is carried out in the present study. The ambient temperature is taken into the account as well as the time factor (Year). The model was developed in away describing the electric power demand during a summer period. The estimated values of the maximum electrical load is obtained and evaluated on actual peak load data of the Kingdom of Bahrain.

Environmental Impacts of Grid Connected High Concentrated Photovoltaic Systems Adapted for Peak Load Minimization in Hot Climate

High concentrated PV multi-junction solar cells (HCPV) likely present a favorable alternative to achieve low cost of energy. However, multi-junction solar cell has different characteristics which should be settled before they can be adapted for large scale energy generation. Peak energy consumption in Kuwait usually occurs in periods of utilizing air conditioning systems which are essentially used in almost all year around in harsh climate like Kuwait. Power consumed at peak times is more costly than power needed to satisfy loads at regular consumption times. The main goal of the present research is to increase HCPV solar cells’ efficiency, to decrease maximum power cost in Kuwait. Multi-junction solar cells performance in weather conditions of Kuwait is investigated employing a single diode equivalent circuit model. The model developed considers the impacts of concentration ratio as well as temperature. Most research in literature review usually neglects shunt resistance of the diode, however this resistance is taken into consideration in current developed theoretical model. To calibrate the present model, current predictions are compared with corresponding measured data provided by multi-junction solar cell manufacturer. The total root mean square errors in the present model predictions are about 1.8%. This means that current developed model of single diode model which takes into account shunt resistance impacts gives precise and reliable data. HCP electrical efficiency is noticed to rise as concentration increases but to a certain concentration value, then it begins to decrease. In addition, utilizing HCPV linked to grid satisfies great decrease in maximum load. Power produced from HCPV modules is utilized to provide energy needs to a family in normal Kuwaiti family home to evaluate HCPV environmental effects. HCPV modules slopes and areas are changed to accomplish peak energy production all over the year. Present results reveal that optimum power production corresponds to HCPV modules directed to south and having latitude of 25°. In addition, employing HCPV modules can avoid approximately 1.55 ton of emitted CO2 per year. In conclusion, current work reveals the advantage impacts of grid connected HCPV in Kuwait weather.

Virtual strain loading method for low temperature cohesive failure of asphalt binder

Cohesive failure is one of the primary reasons for low-temperature cracking in asphalt pavements.Understanding the micro-level mechanism is crucial for comprehending cohesive failure behavior.However,previous literature has not fully reported on this aspect.Moreover,there has been insufficient attention given to the correlation between macroscopic and microscopic failures.To address these issues,this study employed molecular dynamics simulation to investigate the low-temperature tensile behavior of asphalt binder.By applying virtual strain,the separation work during asphalt binder tensile failure was calculated.Additionally,a correlation between macroscopic and microscopic tensile behaviors was established.Specifically,a quadrilateral asphalt binder model was generated based on SARA fractions.By applying various combinations of virtual strain loading,the separation work at tensile failure was determined.Furthermore,the impact of strain loading combinations on separation work was analyzed.Normalization was employed to establish the correlation between macroscopic and microscopic tensile behaviors.The results indicated that thermodynamic and classical mechanical indicators validated the reliability of the tetragonal asphalt binder model.The strain loading combination consists of strain rate and loading number.All strain loading combinations exhibited the similar tensile failure characteristic.The critical separation strain was hardly influenced by strain loading combination.However,increasing strain rate significantly enhanced both the maximum traction stress and separation work of the asphalt binder.An increment in the loading number led to a decrease in separation work.The virtual strain combination of 0.5%-80 provided a more accurate representation of the actual asphalt's tensile behavior trend.

垭口微地形下档内线路不均匀覆冰研究

明确垭口地形因子对垭口输电线路覆冰的影响规律,对山区输电线路的差异化防冰非常关键。该文基于水文分析中反地形理论提出山腰垭口,建立垭口风场数值模型,并通过风洞实验验证该模型。依据垭口风场分布,选定3类垭口线路的架设路径,得出垭口线路的风速区间。将初始状态下导线单次覆冰冰层厚度不得超过线径的7%作为覆冰步长取值依据,循环计算流场、粒子传输模型、热力学方程得出线路风速区间内导线的覆冰情况,进而得出垭口线路的冰荷载曲线,山腰、山脉、双山垭口线路冰荷载曲线在弧垂区分别出现了弯折、下行、下凹的走势。通过野外垭口线路自然覆冰实验,验证了覆冰计算的有效性,证实横跨垭口线路的不均匀覆冰性,不均匀覆冰规律与计算冰荷载曲线类似。计算不同地形因子组合下3类垭口的冰荷载曲线,并提出最大应力比概念,作为评判覆冰所引起线路事故可能性的标准,量化了不同垭口地形因子与线路最大应力比之间的关系。

考虑风载因素的玻璃幕墙清洁机器人设计

围绕高楼玻璃幕墙机器人自动清洁中的风载问题,设计了一款考虑风载因素的真空吸盘吸附的框架式爬壁机器人。针对玻璃幕墙清洁机器人的框架式结构进行步态规划。基于空间力学理论建立了玻璃幕墙清洁机器人在风载下的力学平衡模型,得到了风载大小与机器人吸盘吸附力之间的力平衡方程。在Workbench中对风载作用下的清洗机器人本体进行了有限元分析,得到了机器人模型的应力云图与变形云图。实验测试结果表明:在极限风载作用下,机器人的最大应力点位于吸盘支架,最大变形点位于主架板中心。在真实风载下对机器人进行攀爬运动仿真分析,机器人可以在极限风载下稳定地工作,不会发生滑移和倾覆,验证了力学模型和设计模型的正确性。

基于S变换双阈值法的汽车零部件载荷谱加速编辑

针对S变换编辑法加速编辑效果不佳的问题,提出了一种基于S变换双阈值编辑方法。该方法先对载荷谱进行S变换以获取最大幅值谱,在以双阈值识别并保留的幅值谱片段为依据保留对应的载荷谱片段后,再将其拼接成加速后的载荷谱,最后对比分析S变换双阈值编辑法与S变换编辑法编辑的加速谱的统计参数、功率谱密度、穿级计数和疲劳仿真结果。研究结果表明,S变换双阈值编辑法可明显压缩原始载荷时间,且其压缩效率高于S变换编辑法,转向节的疲劳损伤和寿命分析误差更小,适用于汽车零部件载荷谱加速编辑研究。

基于多端口网络理论的多负载WPT系统效率最大化研究

针对多负载无线电能传输系统效率的最大化问题,采用多端口网络理论分析并将系统效率最大化下的最优负载值问题转为求解广义特征值问题。首先,搭建单输入多输出多负载无线电能传输系统模型,结合端口网络理论和广义瑞利商深入研究系统最佳负载和最大效率之间的关系。在系统参数确定的前提下,通过对系统负载值进行设计,可以实现系统达到最高效率运行的状态,并应用对偶原理将理论成果推广至多负载电容式无线电能传输系统中;其次,采用遗传算法对多负载无线电能传输系统效率进行寻优,确定最佳负载值的正确性和可行性;最后,搭建了基于S-S拓扑的电感式无线电能传输系统实验平台,将单输入两输出、单输入三输出、单输入两不同、单输入三不同输出负载系统作为样本,仿真和实验数据对比验证了所提方法的正确性及最佳负载的可行性。

江西省用电量的时空演变特征及影响因素分析

为方便电能供应者提前规划和优化供电配置,采用空间自相关Moran指数和经济计量方法对江西省用电量的空间相关性及其驱动因素进行了实证分析。研究结果表明,各市用电量存在明显空间差异,高值和低值相互环绕。通过对最大信息系数筛选出的驱动因素进行定量分析,发现除出生率外,发电量、GDP、人口总数、劳动力和工业用电量对用电量的增加具有正向促进作用,工业用电量和GDP是决定电力消费的关键因素。

电机学中的一些“反常”现象及其成因分析

描述了电机学中的一些“反常”现象,分析了这些现象的成因,并用简明的语言进行归纳,为相关领域的研究人员提供一定参考。