Integrated shale gas supply chain design and water management under uncertainty

The development of shale gas resources is subject to technical challenges and markedly affected by volatile markets that can undermine the development of new projects. Consequently, stakeholders can greatly benefit from decision-making support tools that integrate the complexity of the system along with the uncertainties inherent to the problem. Accordingly, a general methodology is proposed in this work for the evaluation of integrated shale gas and water supply chains under uncertainty. First, key parametric uncertainties are identified from a candidate pool via a global sensitivity analysis based on a deterministic optimization model. Then, a two-stage stochastic model is developed considering only the key uncertain parameters in the problem. Moreover, the merits of modeling uncertainty and implementing the stochastic solution approach are evaluated using the expected value of perfect information and the value of the stochastic solution metrics. Furthermore, the conditional value-at-risk approach was implemented to evaluate different risk-aversion levels and the corresponding impacts on the shale gas development plan. The proposed methodology is illustrated through two real-world case studies involving six and eight potential well-pad locations and two options of well-pad layouts. © 2018 American Institute of Chemical Engineers AIChE J, 65: 924–936, 2019     

A Bayesian Approach to Batch Process Scheduling

The problem of decision timing in the context of batch scheduling is addressed in this paper. The representation of time in any scheduling model affects the number of integer variables and the convexity of the model. The usual procedure in batch process scheduling is to divide the scheduling horizon into equal size intervals to achieve the required accuracy. This construction generates a formulation with a potentially large number of binary variables. In this paper, the time events arising in the schedule are modeled directly, and thus the use of binary variables over periods during which no changes in system state occur is avoided. The problem is formulated as a mixed integer nonlinear program (MINLP). The Bayesian heuristic (BH) approach is used to implement a global optimization algorithm which effectively solves the resulting model. Computational comparisons using two text examples are made against a UDM (uniform discretization model) formulation. The results suggest that the BH approach combined with the nonuniform time discretization formulation shows promise for the solution of batch scheduling problems.     

Comparison of energy and material recovery of household waste management from the environmental point of view – Case Kaunas,Lithuania

The results of life cycle assessment of five different energy recovery-based waste management system options are presented. The system options were designed for the city of Kaunas, Lithuania. The Kaunas model was formed according to the Simple Integrated System Management concept developed at Lappeenranta University of Technology. CML2001 was selected as the method according to which the life cycle impact assessment profiles were compiled and analyzed.The results suggest that energy recovery from biowaste, paper and cardboard derived from households could be a more recommendable waste management option than material recovery of the fractions (composting of biowaste and recycling of paper and cardboard). The calculations were carried out with limited process information, and cannot thus be generalized in all parts.     

Ontological informatics infrastructure for pharmaceutical product development and manufacturing

Informatics infrastructure plays a crucial role in supporting different decision making activities related to pharmaceutical product development, pilot plant and commercial scale manufacturing by streamlining information gathering, data integration, model development and managing all these for easy and timely access and reuse. The foundation of such an infrastructure is the explicitly and formally modeled information. This foundation enables knowledge in different forms, and best manufacturing practices, to be modeled and captured into tools to support the product lifecycle management. This paper discusses the development of ontologies, Semantic Web infrastructure and Web related technologies that make such an infrastructure development possible. While many of the issues addressed in this paper are applicable to a wide spectrum of molecular-based products, we focus our work on the development of pharmaceutical informatics to support Active Pharmaceutical Ingredient (API) as well as drug product development as case studies to illustrate the various aspects of this infrastructure.     

Streaming plasma instability of photoexcited electrons in semiconductors

It is shown that in semiconductors, in crossed steady electric and magnetic fields, at low lattice temperatures, the streaming plasma instability of photoelectrons is possible. The instability is studied in linear and nonlinear regimes. The electric field and electron mean velocity oscillations with frequency proportional to recombination rate are obtained.     

Optimal design of multiperiod batch‐storage network including transportation processes

An optimally designed of batch‐storage network that uses a periodic square wave model provides analytical lot‐sizing equations for a complex supply chain network characterized as a multisupplier, multiproduct, multi‐stage, nonserial, multicustomer, cyclic system, with recycling or remanufacturing. The network structure includes multiple currency flows and material flows. The processes involve multiple feedstock and product materials with fixed compositions that are highly suitable for production processes. Transportation processes that carry multiple materials of unknown composition are included in this study, and the time frame is varied from a single infinite period to multiple finite periods to accommodate nonperiodic parameter variations. The objective function in the optimization is chosen to minimize the difference between the opportunity costs of currency/material inventories and stockholder benefits given in the numeraire currency. Expressions for the Kuhn‐Tucker conditions for the optimization problem are reduced to a multiperiod subproblem describing the average flow rates and the analytical lot‐sizing equations. The multiperiod lot‐sizing equations are shown to differ from their single‐period counterparts. The multiperiod subproblem yields a multiperiod planning model that has many advantages over existing planning models. For example, it contains terms that represent operation frequency dependent costs. Realistically sized numerical examples that deal with multinational corporations are formulated and tested. The effects of corporate income taxes, interest rates, and exchange rates are presented. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Identification of electrode surface blocking by means of thin-layer cell: 1. The model

A new method for the identification of electrode surface blocking, based on the measured differences of the diffusion limiting current densities in a thin-layer cell and in a cell with rotating-disk electrode is presented. An equation describing the diffusion limiting current density dependence on the inter-electrode distance in a thin-layer cell was derived. Experimental results were obtained from measurements with model electrodes to demonstrate the possibilities for unambiguous identification of surface blocking phenomena. A model electrode, covered with a partially conductive blocking layer was also discussed and the appearance of two diffusion limiting current density levels on the voltammograms was experimentally verified.