Sefficiency (sustainable efficiency) of water–energy–food entangled systems

Water–energy–food (WEF) entanglement is intensifying and technology is being presented as a crucial solution. But time and again the implemented alternative manifests results contrary to the objectives of design or management. To advance water security, transparent and complete input–output methodologies are needed. Here, a Sefficiency (sustainable efficiency) framework is used to reason through systemic analyses of options for WEF schemes by using water quantity within a comprehensive water balance, and quality and benefits in a multilevel water-use system. An energy regime (cost and normalized functions) and Sefficiency compute performance of four cases that show flaws both conceptually and practically in current policy and scientific tendencies.     

Effective efficiency in water resources management using efficiency elasticity index

Effective efficiency (EE) is a water use performance indicator of a system, integrating net evapotranspiration, volumes of water in and out of the system (including reused water) and their qualities. In order to analyse the nature of management and its options in promoting efficiencies, an efficiency elasticity index (EEI) is developed using EE. The maximum value of EEI for a given net evapotranspiration sets a threshold value for EE under which the management of the system should be improved. This makes it possible to evaluate how good the management of a system is and allows the decision makers to analyse efficiency targets using a graphical approach (assuming that interventions have the same costs). Hypothetical examples and real irrigation cases from United States and Egypt show the practical utility of EE and the methodology developed through the use of EEI. It is also shown that classical efficiency should be used with caution.     

Performances of chaos-coded modulation concatenated with Alamouti’s space–time block code

Recently, some works have shown that it was possible to obtain quite good bit error rate performances over an additive white Gaussian noise channels with chaotic systems. In this research field, this paper proposes new insights for the chaos-coded modulation (CCM) schemes originally proposed by Kozic et al. (2003; IEEE Trans Circuits Syst Regul Pap 53:2048–2059, 2006). A detailed study of the distance spectrum of such schemes is proposed and an approximation of its distribution by means of Gaussian or Rayleigh mixtures is given. Furthermore, using these approximate distributions, a complete study of the performances of these CCM schemes when they are concatenated with a space–time block code is proposed. Accurate bounds are obtained even in the case of time-selective channels.     

Sustainability assessment tool for the decision making in selection of energy system—Bosnian case

In this paper the multi-criteria sustainability assessment of various options of the energy power system of the JP Elektroprivreda of Bosnia and Herzegovina is performed. The rehabilitation of a 110 MW Thermal Power Unit is compared with other options, such as: a thermal power unit with a coal-fueled boiler with combustion in fluidized bed; combined cycle gas turbine plants; hydropower plant, power plants based on solar energy (photovoltaic [PV] systems); wind turbines; and biomass power plants. The assessment methodology comprise a system of stochastic models of uncertainty, enabling decision makers to perform the assessment of various systems, as well as to obtain normalization indexes by using non-numeric (ordinal), non-exact (interval) and non-complete information (NNN-information). Through the analysis of multi-criteria assessment of potential options, the decision-makers are able to evaluate options and select the optimal new power plant capacity.     

Sustainability Assessment of Aluminum Heat Sink Design

The present effort addresses the application of sustainability criteria to the design of "heat sinks" used to cool advanced microelectronic components. The sustainability assessment is based on several criteria, including the use of natural resources, the environment, social welfare, and economic impact. The development of forced convection heat sinks, which are compatible with sustainable development, involves a subtle balance between the achieved thermal performance and the investment of material and energy in the fabrication and operation of the heat sink. It is shown that sustainability criteria can be used to select the environmentally optimal configuration among the most promising heat sink designs, including the lowest pumping power, the least mass of material, and the lowest total (fabrication and operation) energy for a specified application. Of the options considered for cooling a 100 W microprocessor with an aluminum heat sink operating at an excess temperature of 25 K, the heat sink design with the lowest total energy consumption was found to display the highest Sustainability Index.     

Acid‐Based Surfactant‐Aided Dispersion of Multi‐Walled Carbon Nanotubes in Epoxy‐Based Nanocomposites

In this study, the dispersion of multi‐walled carbon nanotubes (MWCNTs) in epoxy was facilitated by an anionic surfactant, linear alkyl benzene sulfonic acid. Different types of composites were prepared using a fixed amount of MWCNTs (0.5 wt%), in absence of solvent/surfactant, in presence of solvent and solvent/surfactant. The composites were characterized using Fourier transform infrared spectrophotometer, thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), universal testing machine, pendulum impact system, X‐ray diffraction, and scanning electron microscope. The epoxy/MWCNTs nanocomposite exhibited significantly higher mechanical properties due to the better dispersion in the presence of the surfactant. The tensile strength and flexural strength were increased by 75% and 108%, respectively. The thermal, structural, and morphological analyses were also excellent as a result of the better dispersion. In addition, the solvent‐surfactant behavior was hypothesized for the epoxy/MWCNTs system. POLYM. ENG. SCI., 59:E80–E87, 2019. © 2018 Society of Plastics Engineers     

Dynamic analysis and design of a semiconductor supply chain: a control engineering approach

The combined make-to-stock and make-to-order (MTS-MTO) supply chain is well-recognised in the semiconductor industry in order to find a competitive balance between agility, including customer responsiveness and minimum reasonable inventory, to achieve cost efficiency while maintaining customer service levels. Such a hybrid MTS-MTO supply chain may suffer from the bullwhip effect, but few researchers have attempted to understand the dynamic properties of such a hybrid system. We utilise a model of the Intel supply chain to analytically explore the underlying mechanisms of bullwhip generation and compare its dynamic performance to the well-known Inventory and Order-Based Production Control System (IOBPCS) archetype. Adopting a control engineering approach, we find that the feedforward forecasting compensation in the MTO element plays a major role in the degree of bullwhip and the Customer Order Decoupling Point (CODP) profoundly impacts both the bullwhip effect and the inventory variance in the MTS part. Thus, managers should carefully tune the CODP inventory correction and balance the benefit between CODP inventory and bullwhip costs in hybrid MTS-MTO supply chains.