Feature signature prediction of a boring process using neural network modeling with confidence bounds

Prediction of machine tool failure has been very important in modern metal cutting operations in order to meet the growing demand for product quality and cost reduction. This paper presents the study of building a neural network model for predicting the behavior of a boring process during its full life cycle. This prediction is achieved by the fusion of the predictions of three principal components extracted as features from the joint time–frequency distributions of energy of the spindle loads observed during the boring process. Furthermore, prediction uncertainty is assessed using nonlinear regression in order to quantify the errors associated with the prediction. The results show that the implemented Elman recurrent neural network is a viable method for the prediction of the feature behavior of the boring process, and that the constructed confidence bounds provide information crucial for subsequent maintenance decision making based on the predicted cutting tool degradation.NSF Industry/University Cooperative Research Center (NSF I/UCRC) forIntelligent Maintenance Systems(IMS).     

Interactive mobile equipment safety task-training in surface mining

Improving the quality of equipment training for the Heavy Equipment Operators (HEO) is a critical task in improving safety and eliminating equipment-related injuries in mining. One of major responsibilities for the HEOs is proper machine inspection. Traditional miner safety training includes the use of hardcopy documents and video instructions. However, modern mobile and computer technology offers tremendous potential to improve the training process. In this study, we apply a 360-degree camera, open-source platform WordPress™, and the software Unity3D in order to create materials and tools for the HEOs safety training to help trainees better understand the pre-shift safety machine inspection. The computer-based safety task training developed in this research is tested and implemented at a surface mine in the southern United States.     

Examination of Trace Metals and Their Potential Transplacental Transfer in Pregnancy

With the ever-growing concern for human health and wellbeing, the prenatal period of development requires special attention since fetuses can be exposed to various metals through the mother. Therefore, this study explored the status of selected toxic (Pb, Cd, Ni, As, Pt, Ce, Rb, Sr, U) and essential trace metals (Mn, Co, Cu, Zn, Se) in the umbilical cord (UC) sera, maternal sera, and placental tissue samples of 92 healthy women with normal pregnancies. A further aim focuses on the potential transplacental transfer of these trace metals. Based on the obtained levels of investigated elements in clinical samples, it was observed that all of the trace metals cross the placental barrier and reach the fetus. Furthermore, statistical analysis revealed significant differences in levels of toxic Ni, As, Cd, U, Sr, Rb, and essential Mn, Cu, and Zn between all three types of analyzed clinical samples. Correlation analysis highlighted As to be an element with levels that differed significantly between all tested samples. Principal component analysis (PCA) was used to enhance these findings. PCA demonstrated that Cd, Mn, Zn, Rb, Ce, U, and Sr were the most influential trace metals in distinguishing placenta from maternal and UC serum samples. As, Co, and Cu were responsible for the clustering of maternal serum samples, and PCA demonstrated that the Pt level in UC sera was responsible for the clustering of these samples. Overall, the findings of this study could contribute to a better understanding of transplacental transfer of these trace metals, and shed a light on overall levels of metal exposure in the population of healthy pregnant women and their fetuses.     

Asymptotic H∞ control of singularly perturbedsystems with parametric uncertainties

This paper deals with the problem of control of singularly perturbed linear continuous-time systems. The authors' attention is focused on the design of a composite linear controller based on the slow and fast problems such that both stability and a prescribed H_∞ performance for the full-order system are achieved. The asymptotic behavior of the composite controller is studied, which is independent of the singular perturbation ϵ when ϵ is sufficiently small. Furthermore, the problem of robust control for the above system with parameter uncertainty is also investigated     

Optimization of geometry of horizontal roof overhangs during a summer season

This paper presents the simultaneous optimization of the depths of the horizontal roof overhangs for the design of a residential summer house for house operation during summer season in Belgrade, Serbia. The overhangs facing south, east, and west are made by using reinforced concrete. The two objective functions are used such as (1) minimizing the sum of the primary operative energy consumption during the overhang life cycle and the embodied energy in the roof overhangs and (2) maximizing the ratio of the annual primary operating energy saving and the annualized embodied energy of the applied roof overhangs. For the optimization, the Hooke-Jeeves method is used, and the EnergyPlus software is used to simulate energy behavior of the house. The research showed that two different optimizations gave different results. However, if the house is not used during the same time for which the overhangs are optimized, there is a slight increase in primary energy consumption, although the operative energy consumption may be lower.     

A new approach for kinetic modeling and optimization of rubber molding

Although extensive research has been carried out on the understanding of the complex vulcanization process, the influence of reversion through exposure time and temperature on the vulcanization degree remains unclear. Therefore, the main aim of this study was a novel optimization approach that can help the industrial practitioners to select the optimal operating parameters, exposure time, and molding temperature, to achieve desired vulcanization degree of selected product. Spheres of four different diameters (2.5, 5, 10, and 20 cm) were selected as test geometry for simulation and optimization of rubber molding. Obtained vulcanization rheometer data for commercially available rubber blend (NR/SBR) were fitted by a new modeling approach, dividing vulcanization curve into two fitting sets: curing and reversion. The heat transfer equations for chosen geometry were coupled with proposed kinetic model. A new temperature-dependent kinetic parameter x, as the maximal reversion degree, was introduced, enabling determination of the lowest operating molding temperature (T_min = 132.36 °C), preventing high reversion and overheating of the rubber product. The final optimization goal was assessment of the optimal temperature and vulcanization time dependence on the rubber products dimensions. Proposed models have precise prediction with R² values greater than 0.8328 and MAPE less than 2.3099%.     

On emulated nonlinear reduced-order observers for networked control systems

We consider a general class of nonlinear reduced-order observers and show that the global asymptotic convergence of the observation error in the absence of network-induced constraints is maintained for the emulated observer semiglobally and practically (with respect to the maximum allowable transmission interval) when system measurements are sent through a communication channel. Networks governed by a Lyapunov uniformly globally asymptotically stable protocol are investigated. Our results can be used to synthesize various observers for networked control systems for a range of network configurations, as we illustrate it by considering classes of immersion and invariance observers which include the circle-criterion observers.     

Self-assembled polyaniline 12-tungstophosphate micro/nanostructures

Polyaniline (PANI) micro/nanostructures were synthesized by the external-template-free oxidative polymerization of aniline in aqueous solution of 12-tungstophosphoric acid (WPA), using ammonium peroxydisulfate (APS) as an oxidant and starting the oxidation of aniline from slightly acidic media (pH 5.4–5.9). The effect of the initial weight ratio of WPA to aniline on molecular structure, morphology, and physicochemical properties of polyaniline 12-tungstophosphate (PANI-WPA) was investigated by FTIR, Raman and inductively coupled plasma optical emission (ICP-OES) spectroscopies, elemental analysis, X-ray powder diffraction (XRPD), scanning and transmission electron microscopies (SEM and TEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and conductivity measurements. The morphological change of polymerization products during a single polymerization process, from non-conducting submicro-/microspherical oligoaniline intermediates to semiconducting PANI-WPA consisted of self-assembled nanotubes and/or nanorods co-existing with submicro-/microspheres, has been revealed by SEM and TEM. The average diameter of nanorods in PANI-WPA samples decreased with increasing the initial WPA/aniline weight ratio. The incorporation of 12-tungstophosphate counter-ions into PANI matrix has been proved by FTIR, Raman and ICP-OES spectroscopies, TGA and DTA analysis. Electrical conductivity of PANI-WPA increased in the range (2.5–5.3) × 10^?3 S cm^?1 with the increase of the initial WPA/aniline weight ratio. The presence of branched structures and phenazine units besides the ordinary paramagnetic and diamagnetic emeraldine salt structural features in PANI-WPA was proved by FTIR and Raman spectroscopies.     

Calculated and experimental analysis of cause of the appearance of cracks in the running bogie frame of diesel multiple units of Serbian railways

In this paper an analysis of possible causes of crack occurrence on reconstructed diesel multiple units (DMU) exploited on sideline in Serbia was performed. Analyzed DMU were designed in the sixties of the last century in accordance with standards and UIC regulations of that time. During exploitation cracks appeared on the frame of the running bogie and they were locally repaired. With the purpose of eliminating this negative occurrence that has been reducing the availability of DMU, reconstruction of primary suspension and reconstruction of the DMU running bogie frame was performed. The new construction solution of primary suspension is with rubber springs. In the designing of the new running bogie frame fatigue loads were taken into account. After approximately two and a half years of exploitation, cracks appeared again on frames of the running bogie of DMU and they are the subject of this work. This work gives an analysis of the cause of crack occurrence and investigates links between specific exploitation conditions on tracks of Serbian railways and calculations/investigations performed using currently valid UIC regulations. The analysis also includes other influential factors such as welding quality, track quality, DMU and track maintenance quality.     

Nitric oxide-releasing porous silicon nanoparticles

In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment.