Shaligram Pokharel

Global reverse supply chain design for solid waste recycling under uncertainties and carbon emission constraint

The emergence of concerns over environmental protection, resource conservation as well as the development of logistics operations and manufacturing technology has led several countries to implement formal collection and recycling systems of solid waste. Such recycling system has the benefits of reducing environmental pollution, boosting the economy by creating new jobs, and generating income from trading the recyclable materials. This leads to the formation of a global reverse supply chain (GRSC) of solid waste. In this paper, we investigate the design of such a GRSC with a special emphasis on three aspects; (1) uncertainty of waste collection levels, (2) associated carbon emissions, and (3) challenges posed by the supply chains global aspect, particularly the maritime transportation costs and currency exchange rates. To the best of our knowledge, this paper is the first attempt to integrate the three above-mentioned important aspects in the design of a GRSC. We have used mixed integer-linear programming method along with robust optimization to develop the model which is validated using a sample case study of e-waste management. Our results show that using a robust model by taking the complex interactions characterizing global reverse supply chain networks into account, we can create a better GRSC. The effect of uncertainties and carbon constraints on decisions to reduce costs and emissions are also shown.

An integrated resource allocation and distribution model for pre-disaster planning

We model a disaster preparedness problem for the supply of a commodity.We consider an integrated pre- and post-disaster preparedness planning model.The use of multiple supply points reduces supply deprivations at the demand points.Deprivation cost structure significantly affect the proportion of pre- and post-disaster allocations. In this paper, a three-echelon network model is proposed for integrated emergency preparedness and response planning for the distribution of emergency supplies. The model minimizes the social cost to identify a set of potential supply points (SPs) at the highest echelon, where supply items are consolidated and sent to the prepositioning facilities. The sum of logistics and deprivation costs incurred by the population due to the lack of access to goods or services, is considered as the social cost in this model. The deprivation cost is assumed to increase exponentially with the deprivation time. The model also considers pre-disaster and post-disaster purchasing decisions at the SPs, and allows direct shipments from SPs and prepositioned facilities to the demand points. Numerical analysis shows that multiple supply sources can ensure efficient distribution of the supplies and reduce the deprivation costs. The results also indicate that partial prepositioning and post-disaster purchasing can reduce the shortage in emergency supplies.

Skills of engineers in knowledge based economies: A comprehensive literature review, and model development

Recent studies emphasize the needs of a wider set of skills engineers require than ever thought. In this paper, authors report on a systematic literature review on this issue. Findings of the review are spanned over two main folds: 1- A conceptual ontological framework of engineering skills in the context of generic- and employability- skills of KBS and KBEs citizens and workforce, and 2- A global set of 24 mutual common skills, but different in topology, between engineering and generic competencies. The work outlined in this paper is probably one of the most comprehensive and wide scan of literature on the required talent and skills of current and future engineers.

A comprehensive annual delivery program for upstream liquefied natural gas supply chain

Developing a cost-effective annual delivery program (ADP) is a challenging task for liquefied natural gas (LNG) suppliers, especially for LNG supply chains with large number of vessels and customers. Given significant operational costs in LNG delivery operations, cost-effective ADPs can yield substantial savings, adding up to millions. Providing an extensive account of supply chain operations and contractual terms, this paper aims to consider a realistic ADP problem faced by large LNG suppliers; suggest alternative delivery options, such as split-delivery; and propose an efficient heuristic solution which outperforms commercial optimizers. The comprehensive numerical study in this research demonstrates that contrary to the common belief in practice, split-delivery may generate substantial cost reductions in LNG supply chains.

Building thermal energy modeling with loss minimization

Abstract The thermal losses in buildings are significant energy sinks. The Energy Semantic Network (ESN) is a new method for finding these losses at the design stage, as well as for the existing structures. The research purpose of ESN is to take into consideration the governing factors of building thermal performance (i.e. the insulation materials, the dimensions, the loads, and the schedules of people interactions), associate these factors with any building of choice, and to subject the model to range of dynamical changes, that will help to make the decisions for improving the building thermal performance. The current work is only an early stage on ESN, the end goal of ESN is to evaluate the thermal energy conservation technologies with respect to the dynamical thermal changes, and track the dominant sinks resulting from these changes. Currently, the energy conservation technologies present an opportunity for reducing the utility use, and, thereby, the savings in capital for long term performance. The thermal energy conservation problems are unique to every building, due to the storage and the supply of the energy in response to the seasonal demands, structure, and the nature of the building utilization (the involvement of people). With the current simulation software, such as Energy Plus, there exists a convenient way of simulating the annual building performance, without the tediousness of monitoring the physical building. However, in that case, any particular spontaneous effects may not be completely accounted. The ESN structure is intended to make up for the spontaneous effects, and be accountable for possible spikes in the energy use that may occur throughout the year. Such spikes in energy consumption do not have to be singular, because it is possible to assign an array of situations where energy losses occur and track them to the specific location. The use of ESN for tracking the energy losses can lead to a solution for preventing similar spikes in the future by isolating the most significant sink. The enclosed research on the ESN method includes the foundations of ESN, the case study of a hypothetical hotel located in Ontario, and a detailed Simulink representation of ESN.

Key performance indicators (KPIs) for evaluation of energy conservation in buildings

The main objectives of this paper are to: identify key performance indicators (KPIs) related to intelligent buildings (economical, environmental, reliability, and quality), and; propose a simulation framework for evaluation of these KPIs. Energy simulation of a building is a key to study the energy efficiency in the building. This paper presents an integrated framework based on Google™ SketchUp, OpenStudio, ResultViewer, and EnergyPlus software for energy simulation of a large hotel building with different types of energy zones, loads schedules, and set-points. The aim of this paper is to calculate some important KPIs in a building environment to access the overall efficiency of the building.

Impact of competitive conditions on supplier evaluation: a construction supply chain case study

Abstract This research proposes a multi-criteria decision-making (MCDM) framework and demonstrates the impact of competitive conditions on supplier evaluation process for construction supply chains. The paper focuses on the supply chain of a large-scale housing project in order to illustrate the role of competitive capability and suppliers’ profile and its influence on supplier evaluation based on prevailing supply/market conditions. Various scenarios are investigated to demonstrate the impact of competition on supplier evaluation. The contribution of the study lies in highlighting the impact of supply/market conditions on MCDM decisions causing supplier evaluation ‘imbalance’ and MCDM usage. It is expected that the study will be useful for project management, construction, supply chain management, sourcing professionals. The findings of the study are generalisable to projects-based situations such as petroleum refinery and ship building where bill of materials typically consists of thousands of items and a large number of suppliers are involved.

Integrated Optimization for Stock Levels and Cross-Training Schemes with Simulation-Based Genetic Algorithm

A spare part supply system for repairable spares in a repair shop is modeled as a set of heterogeneous parallel servers that have the ability to repair only certain types of repairables. The proposed model minimizes the total cost of holding inventory for spare parts, cost for backorder arising from downtime of the system due to the lack of spare parts and the cost of crosstraining for servers. Simulation-based Genetic Algorithm (GA) is proposed to optimize inventory levels and to determine the best skill assignments to servers, i.e., cross-training schemes. When methodologys performance is compared with total enumeration, tight optimality gaps are obtained.

Systemic framework of competencies of 21st century technical and engineering human resource: A development case for a knowledge based Economy in Qatar

The required talent of 21st century engineering and technology human resource is significantly different and more complex than what has been needed ever before. Numerous relevant studies have been conducted during the last decade or two. The studies generally follow a needs based approach rather than a systemic study. In a systemic study for understanding the requirements, architectural framework needs to be developed first by decomposing the problem in to various sub requirements and then finally integrating them to provide a holistic view of the requirements. The paper provides, probably, the first systemic framework for investigation of needed engineering and technology competencies in a national context. The other contribution of the paper is a decomposition of different terms and definition related to skills, attributes, and competencies development into a systemic dynamic model.

Simulation based particle swarm optimization of cross-training policies in spare parts supply systems

We study a single location supply system for repairable spare parts. The system consists of a multi-server repair shop and inventory with ready-to-use spare parts. When a failed part is received, a new (or as-good-as-new) replacement part is sent back, and the failed part is forwarded to the repairshop. In the case of unavailability of spare parts, failed requests are backordered and fulfilled when a ready-for-use part of the same type is received from the repairshop. The repair shop has several multi-skilled parallel servers (technicians) that are capable of handling certain types of spares. In this paper, we propose a Particle Swarm Optimization heuristic combined with Discrete-Event Simulation for optimizing the cross-training policy (skill assignment scheme) while minimizing the total system cost (consisting of inventory costs, backorder penalty cost, server cost and skill cost).