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Analysis of Waste-Rock Transportation Process Performance in an Open-Pit Mine Based on Statistical Analysis of Cycle Times Data

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Engineering（科研） 2017年第7期9卷 649-679页

作者： Samwel Victor Manyele Department of Chemical and Mining Engineering College of Engineering and Technology University of Dar es Salaam Dar es Salaam Tanzania

In this paper, the performance of a waste rock transportation process in an open pit mine was assessed by using cycle time data. A computerized truck-excavator dispatch system was used to record the cycle times. The process was broken into seven steps (or components of the total cycle), durations of which were recorded for a period of 1 month, leading to N = 60,690 data points or dispatches. The open pit mine studied consisted of 12 waste types loaded by 14 excavators and hauled by 49 trucks (at a trucks-to-excavator ratio of 3.5:1) in 75 changing locations. The string-type data was coded using integers to allow a FORTRAN code to extract process performance parameters using statistical analysis. The study established a wide range of parameters including: the waste material generation rate (about 1.73 million t/month, 81% comprising waste rock), truck fill factor, f, total cycle time (Tct), production capacity, theoretical cycle time, non-productive cycle time Tnp, and cycle time performance ratio (CTPR), denoted as Tpr. The factors affecting the process performance include: truck model, excavator model, location (haul distance and road conditions) and material type. For a fixed material type and tonnage, the PDFs of the cycle time components were logarithmic in nature, capable of differentiating performance variations under different factors. It was concluded that the performance of the waste material transportation system in this mine was determined to be acceptable due to mean value of Tpr = 2.432 being closer to unity. Reduction measures were suggested to minimize the cycle time for the process bottlenecks determined from Pareto analysis (that is, full haul, empty haul and loading processes).

关键词： Potentially Acid-Forming (PAF) Rock Non-Acid Forming (NAF) Rock Truck Utilization Truck fill-factor Queuing Time Loading Cycle Time Full and Empty Haul Total Cycle Time Theoretical Cycle Time Non-Productive Cycle Time Cycle Time Performance Ratio

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Investigation of Excavator Performance factors in an Open-Pit Mine Using Loading Cycle Time

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Engineering（科研） 2017年第7期9卷 599-624页

作者： Samwel Victor Manyele Department of Chemical and Mining Engineering College of Engineering and Technology University of Dar es Salaam Dar es Salaam Tanzania

This study presents the effect of excavator model, loading operation location, shift availability and truck-shovel combination on loading cycle time and productivity of an open-pit mine. The loading cycle time was used to assess the material loading system performance which is one of the key components of the total cycle time for material transportation in an open-pit mine. Loading is among the components of cycle time during which material is being handled. The data analyzed?was?collected from a computerized dispatch system at GGM from which 62,000 loading dispatches per month involving several shifts, 14 excavators and 49 trucks were loaded. About 4465 dispatches per excavator and 1276 dispatches per truck were assessed using loading cycle time data for each dispatch for a period of four months (between August and December). Under fixed tonnage loaded and waste type (33 t of non-acid forming waste rock),?it was observed that loading cycle time depends on excavator model, location and truck being loaded. Average cycle times, PDFS?and CDFS of loading cycle time series were used to identify differences in performance under different situations. It was concluded that shift availability for excavators, loading location, excavator model and truck-shovel combinations strongly affect the productivity during loading process in an open-pit mine.

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An Approach to Equivalent Circuit Modelling of Inverted Organic Solar Cells

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Circuits and Systems 2016年第8期7卷 1297-1306页

作者： Nazmul Hossain Sayantan Das Terry L. Alford Department of Electrical Engineering Arizona State University Tempe Arizona USA School of Engineering of Matter Transport and Energy Arizona State University Tempe Arizona USA School of Engineering of Matter Transport and Energy and Department of Electrical Engineering Arizona State University Tempe Arizona USA

A low temperature sol-gel process was used to fabricate zinc-oxide and yttrium-doped zinc oxide layers. These zinc-oxide and yttrium-doped ZnO films were used as electron transport layers in conjunction with P3HT and PC16BM type solar cells. It was demonstrated that annealing and doping of electron transport layer influenced the overall organic solar cells performance. Anneals of ~ 150?C provided the highest device performance. Compared to the undoped zinc oxide, the device with yttrium doped zinc oxide layers showed improved efficiency by about 30%. Furthermore an equivalent circuit was proposed to understand the connection between the electrical and optical characteristics of the device. Comparisons between the simulated and experimental current-voltage(I-V) curves displayed only a 1.2% variation between the curves. Clearly, our experimental and simulated studies provide new insight on the equivalent circuit models for inverted organic solar cells and further improvement on photovoltaic efficiency.

关键词： Inverted Organic Solar Cell Equivalent Circuit fill-factor P3HT/PCBM ETL Yttrium-Doped ZnO

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Retraction:Modeling Electrical Characteristics of a pn-Junction Silicon Solar Cell Using PSpice

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Smart Grid and Renewable Energy 2012年第2期3卷 133-138页

作者： Mohammad Ziaur Rahman Shahidul Islam Khan De- partment of Electrical and Electronic Engineering Bangladesh University of Engineering and Technology Dhaka Bangladesh. Department of Electrical and Electronic Engineering Ahsanullah University of Science and Technology Dhaka Bangladesh

Short Retraction Notice The article has been retracted due to the investigation of complaints received against it. The substantial portions of the text came from Luis Casta?er and Santigo Silvestre, " Modelling photovoltaic systems using PSpice".The scientific community takes a very strong view on this matter and we treat all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No.2 133-138, 2012, has been removed from this site.

关键词： Solar Cell PSpice Short Circuit Current Quantum Efficiency Open Circuit Voltage fill-factor Efficiency

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Equivalent Circuit Modification for Organic Solar Cells

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Circuits and Systems 2015年第6期6卷 153-160页

作者： Nazmul Hossain Sayantan Das Terry L. Alford Department of Electrical Engineering Arizona State University Tempe AZ USA School of Engineering of Matter Transport and Energy Arizona State University Tempe AZ USA

In this work, a newly fabricated organic solar cell based on a composite of fullerene derivative [6,6]-phenyl-C61 butyric acid methyl ester (PCBM) and regioregular poly (3-hexylthiophene) (P3HT) with an added interfacial layer of AgOx in between the PEDOT:PSS layer and the ITO layer is investigated and an equivalent circuit model is proposed for the device. Incorporation of the AgOx interfacial layer shows an increase in fill factor (by 33%) and power conversion efficiency (by 28%). Moreover, proper correlation has been achieved between the experimental and simulated I-V plots. The simulation shows that device characteristics can be explained with accuracy by the proposed model.

关键词： Equivalent Circuit fill-factor Interfacial Layer Organic Solar Cells P3HT/PCBM

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