A Monte Carlo simulation approach for effective assessment of flyrock based on intelligent system of neural network

One of the undesirable phenomena in the surface mines, which results in various hazards for human and facilities, is flyrock. It seems that the careful study of the subject and its effects on the environment can affect the control of flyrock hazards in the studied area. Therefore, the use of intelligent models and methods which are capable of predicting and simulating the risk of flyrock can be considered as an appropriate solution in this regard. The current research was conducted using nonlinear models and Monte Carlo (MC) simulation. The data used in this study consist of 260 samples of rock thrown from a mine in Malaysia. The parameters used in these models include hole’s diameter (D), hole’s depth (HD), burden to spacing (BS), stemming (ST), maximum charge per delay (MC), and powder factor (PF). At first, multiple regression analysis (MRA) and artificial neural network (ANN) models were used in order to develop a non-linear relationship between dependent and independent parameters. The ANN model was an appropriate predictor of flyrock in the mine. Then using the best implemented model of ANN, the flyrock environmental phenomenon was simulated using MC technique. MC simulation showed a proper level of accuracy of flyrock ranges in the mine. Using this simulation, it can be concluded with 90% accuracy that the Flyrock phenomenon does not exceed 331 m. Under these conditions, this simulation can be used for various areas requiring risk assessment. Finally, a sensitive analysis was carried out on data. This analysis showed MC has the greatest effect on flyrock.     

Fingerprinting Based Indoor Localization Considering the Dynamic Nature of Wi-Fi Signals

Current localization techniques in outdoors cannot work well in indoors. Wi-Fi fingerprinting technique is an emerging localization technique for indoor environments. However in this technique, the dynamic nature of WiFi signals affects the accuracy of the measurements. In this paper, we use affinity propagation clustering method to decrease the computation complexity in location estimation. Then, we use the least variance of Received Signal Strength (RSS) measured among Access Points (APs) in each cluster. Also we assign lower weights to altering APs for each point in a cluster, to represent the level of similarity to Test Point (TP) by considering the dynamic nature of signals in indoor environments. A method for updating the radio map and improving the results is then proposed to decrease the cost of constructing the radio map. Simulation results show that the proposed method has 22.5% improvement in average in localization results, considering one altering AP in the layout, compared to the case when only RSS subset sampling is considered for localization because of altering APs.

     

Studies with inorganic precipitate membrane: evolution of thermodynamically effective fixed charge density and test of the most recently developed theory of membrane potential based on the principles of non-equilibrium thermodynamics

Electrical potentials developed across nickel, manganese chromate and cupric iodide membranes using various 1:1 electrolytes are reported. Thermodynamically effective fixed charge density, which is an important parameter governing the membrane phenomena, has been evaluated by the recently developed theory of Nagasawa et al. Most recently developed theories of Toyoshima and Nozaki based on the principles of the irreversible thermodynamics has been examined to predict the bi-ionic potentials developed across the membranes. Theoretical predictions were borne out quite satisfactorily by our experimental results.     

基于非线性静态分析和软件的公路桥抗震评估

受地震扰动时,可以通过一系列方法对桥的响应进行评估。传统的方法是采用线性静态或动态分析结合适当的修正来说明非弹性响应,而现行的实践着重强调非线性静态分析方法。本研究采用线性动态分析程序,对两跨公路桥的初步地震响应进行分析以确定潜在的非弹性响应。按照两个非线性静态分析方法对桥进行分析,评估了两种方法所预测的全部响应的差别以及采用各种软件进行非线性静态分析的效率。结果显示:所采用的两种不同非线性响应预测的非线性静态分析方法,由于存在大量的简化,都不能获得正确的结果。此外,研究还揭示在综合分析和提供破坏过程图方面,一些软件更适合进行非线性静态分析(如塑性铰的性能)。     

Microfabricated Biomaterials for Engineering 3D Tissues

Mimicking natural tissue structure is crucial for engineered tissues with intended applications ranging from regenerative medicine to biorobotics. Native tissues are highly organized at the microscale, thus making these natural characteristics an integral part of creating effective biomimetic tissue structures. There exists a growing appreciation that the incorporation of similar highly organized microscale structures in tissue engineering may yield a remedy for problems ranging from vascularization to cell function control/determination. In this review, we highlight the recent progress in the field of microscale tissue engineering and discuss the use of various biomaterials for generating engineered tissue structures with microscale features. In particular, we will discuss the use of microscale approaches to engineer the architecture of scaffolds, generate artificial vasculature, and control cellular orientation and differentiation. In addition, the emergence of microfabricated tissue units and the modular assembly to emulate hierarchical tissues will be discussed.     

Model for boiling explosion during rapid liquid heating

The process of rapid liquid heating with a linearly increasing boundary temperature condition has been simulated by applying the analytical solution of 1D semi-infinite heat conduction in association with the molecular theory of homogeneous nucleation boiling. A control volume having the size of a characteristic critical cluster at the liquid boundary is considered, and the corresponding energy balance equation is obtained by considering two parallel competing processes that take place inside the control volume, namely, transient external energy deposition and internal energy consumption due to bubble nucleation and subsequent growth. Depending on the instantaneous rate of external energy deposition and boiling heat consumption within the control volume, a particular state is defined as the boiling explosion condition in which bubble generation and growth cause the liquid sensible energy to decrease. The obtained results are presented in terms of the average liquid temperature rise within the control volume, maximum attainable liquid temperature before boiling explosion and the time required to achieve the condition of boiling explosion. The model is applied for the case of water heating at atmospheric pressure with initial and boundary conditions identical to those reported in the literature. Model predictions concerning boiling explosion are found to be in good agreement with the experimental observations. The boiling explosion condition as predicted by the present model is verified by comparing the heat flux across the liquid–vapor interface with the corresponding limit of maximum possible heat flux, q_max,max, at the time of boiling explosion. A comparative study between the actual heat flux and the limit of maximum heat flux, q_max,max, at the time of boiling explosion for different rates of boundary heating indicates that, with much higher boundary heating rates, it is possible to heat the liquid to a much higher temperature before theoretical instantaneous boiling explosion occurs.     

CWIPL II,a mechanism for improving throughput and lead time in unbalanced flow line

Critical WIP loops II (CWIPL II) is a proposed material flow control mechanism for an unbalanced flow line environment. CWIPL II is based on CWIPL and it determines critical loops in unbalanced lines. The WIP of critical loops identifies the time of releasing raw material to the line. CWIPL II proposed a new classification for unbalanced flow line which is ‘near unbalanced flow line’ and ‘perfect unbalanced flow line’. In near unbalanced line, there is one bottleneck and a raw material release to the line if ‘WIP of the bottleneck’ or ‘WIP upstream the bottleneck’ is less than defined level. In perfect unbalanced line there are multiple bottleneck and a raw material release to the line if ‘WIP upstream the slowest machine’ or ‘WIP between two primary bottleneck’ is less than defined level. Like CWIPL, the necessary condition for releasing the raw material is ‘idleness of the first machine’. CWIPL II is compared with CONWIP and TOC by simulation. Different scenarios are employed in the comparison analysis. The scenarios address variables such as number of machines, processing time distribution, WIP target level. Location of slowest machine and location of two primary bottlenecks are considered in examples. Simulation results and statistical tests of 141 numerical examples show that CWIPL II improves lead time in near unbalanced line and throughput in perfect unbalanced line compared with TOC. Because of the trade off between line throughput and lead time, the mechanism that improves one of them while maintaining the other at previous level is valuable. It is shown that CWIPL II has improved TOC in the cases that TOC hasn’t improved CONWIP.     

The effect of natural antioxidants extracted from plant and animal resources on the oxidative stability of soybean oil

The objective of this study was to evaluate and compare the antioxidant activity of protein hydrolyzates isolate (PHI) from Crucian carp (Carassius carassius) fish and cow's intestine along with microwave-assisted olive leaf extract (OLE) encapsulated by Arabic gum and maltodextrin, in soybean oil. The antioxidant activity of PHIs at three concentrations of 200, 500 and 1000 mg/kg and OLE samples containing 70 mg/kg total phenolics during 20 days storage was evaluated by peroxide value, TBA value, p-anisidine value and Rancimat stability test. The fish PHI at concentration of 1000 mg/kg, cow's intestine PHI at 500 and 1000 mg/kg and OLE encapsulated with Arabic gum showed best oxidative protection activity (more than BHT at 100 and 200 mg/kg). OLE had a suitable antioxidant activity in soybean oil and encapsulation improved the thermal stability of phenolic compounds, but on the other hand, it decreased the antioxidant efficiency of OLE.     

Influence of different metal over-layers on the electrical behaviour of the MIS Schottky diodes

We have employed technology computer-aided design – a Synopsys® tool to carry out a comparative study of the electrical behaviour of the metal–insulator–semiconductor Schottky diodes with different metal contacts (Ag, Au, Pt and Cr), on n-Si(100). We employed physics models to determine the Shockley–Read–Hall (SRH) and Auger recombination rates as a function of electric field profile in the depletion region. An insight was obtained as variation in the electric field at the metal–semiconductor interface due to work function variation affected the current mechanisms and recombination rates. The results were compared with the existing models. On the basis of analysis, merits and demerits of Schottky junctions formed due to these metals are discussed. The ideality factor of Au and Pt was found to be just around 2.0, while it was higher for Cr and Ag. However, the barrier height in the case of Cr was small, thus making it another possible metal layer for the Schottky contact. Similarly, SRH recombination rates were almost negligible for Au and Pt metal layer and became appreciable for Cr and much higher in Ag, making it not a good choice for the Schottky contact.