Energy–water–food nexus in the Spanish greenhouse tomato production

The nexus energy–water–food of the tomato greenhouse production in the Almeria region (Spain) has been studied following a Process Systems Analysis Method connecting the ecosystem services to the market demands with a holistic view based on Life Cycle Assessment. The management of the agri-food subsystem, the industrial subsystem and the urban subsystem plays an important role in the nexus of the E–W–F system, where transport and information technologies connect the three subsystems to the global markets. The local case study of the tomato production in Almeria (Spain) has been developed as an example of the food production under cropland restrictions, semiarid land. After study of the economic and social sustainability in time, the evolution of the ecosystem services supply is the main restriction of the system, where after the land use change in the region, water and energy supply play the mean role with a trade-off between the water quality degradation and the economic cost of the energy for water desalination. Water footprint, Carbon footprint and Chemicals footprint are useful indicators to the environmental sustainability assessment of local alternatives in the E–W–F system under study. As it is shown in the conclusions, the holistic view based on the process analysis method and the life cycle assessment methodology and indicators is an useful tool for decision support.     

Optimizing residential density based on water–energy–carbon nexus using UTilités Additives (UTA) method

High-density housing is primarily constructed to decrease per capita civil infrastructure and land resource. Multi-family residences are preferred to single-family residences for neighbourhood densification changing per capita landscaping, affecting residential water and energy demand. These alterations also affect energy-associated carbon emissions and landscaping-associated carbon sequestration, revealing the existence of the water–energy–carbon (WEC) nexus. This study has developed a holistic framework for optimal residential density based on WEC nexus. The conflicting criteria water footprint, energy use, net carbon emissions, life cycle cost, aesthetic value, and government priority, associated with the WEC nexus in various densities, were evaluated using the UTilités Additives method. The developed framework was applied to a planned neighbourhood in the Okanagan Valley (British Columbia, Canada) by preparing 11 alternative designs with different residential densities. Neighbourhood scenarios with different criteria weights were studied. Results show that per capita water footprint, energy use, net carbon emissions, and life cycle cost have a power relationship with net residential density despite a linear relationship between population and net residential density. The estimated optimal net residential density is approximately 260 persons/ha for most of the scenarios. The findings present the benefits of building medium- to high-density housing to achieve an optimal WEC nexus.     

Enhanced water resistance and energy performance of core–shell aluminum nanoparticles via in situ grafting of energetic glycidyl azide polymer

The application of aluminum nanoparticle is limited due to its passivation Al₂O₃ layer even though it owns extreme specific surface and high reaction activity. In this work, the aluminum nanoparticles were modified via in situ grafting onto energetic glycidyl azide polymer (GAP) to improve the stability and energy-releasing performance. The results showed that GAP was grafted on the nano-aluminum surface with chemical bonds of –O–(CO–NH)– formed, and the thickness of shell layer of GAP could be tuned by changing the relative ratio of reactants. Furthermore, modified nanoparticles show hydrophobicity with static water contact angle changing from 20.2° to 142.4°. Significant increasing stability of aluminum nanoparticles is obtained in hot water, which is evidenced by that around 10 wt% of modified aluminum is reacted after 210 min. Based on the core–shell configurations, (Al@GAP)/fluorine composites were prepared. The violent combustion phenomenon and high release rate profiles revealed high energy-releasing performance with the assistance of GAP. This synthetic strategy may provide an effective approach to prepare other metal nanoparticles, and possess potential application value in the fields of metallized explosives and high-energy structure with energy release.     

Optimization of composition and heat treatment design of Mg–Sn–Zn alloys via the CALPHAD method

This work is focused on the application of the calculation of phase diagrams method for alloy and heat treatment design. We analyzed the influence of Zn content on the precipitation of Mg₂Sn in Mg–Sn–Zn alloys. A comparison with previous studies in the Mg–Sn–Zn system was made according to the published results and computational thermochemistry simulations. The phase evolution in the Mg–Sn–Zn system was evaluated for the different compositions, and the simulations were used for precise alloy and heat treatment design. The composition of the ternary alloy was set as Mg–8wt%Sn–1.25wt%Zn. The Sn and Zn content was designed and confirmed to be within the α-Mg solubility limit at the solution treatment temperature. The addition of Zn and the heat treatment applied resulted in the enhancement and refinement of the Mg₂Sn precipitation. Three Vickers micro-hardness maxima were detected: precipitation of metastable Mg–Zn phases, heterogeneous precipitation of Mg₂Sn on the Mg–Zn precipitates, and Mg₂Sn precipitation in the α-Mg matrix. The CT simulations were found to be a valuable alloy design tool.     

Total energy framework, finite elements, and discretization via Hamilton’s law of varying action

Within the total energy framework which we introduce here for the first time (in contrast to Lagrangian or Hamiltonian mechanics framework), we provide an alternative and have developed in this paper a general numerical discretization for continuum-elastodynamics directly stemming from Hamilton’s law of varying action (HLVA) involving a measurable built-in scalar function, namely, Total Energy ${[{\mathcal{E}}\left({{\boldsymbol{q}},\dot{{\boldsymbol{q}}}}\right): TQ\rightarrow {\mathbb{R}}]}$ . The Total Energy we use herein for enabling the space discretization is defined as the kinetic energy plus the potential energy for N-body systems, and the kinetic energy plus the total potential energy for continuum-body systems. It thereby provides a direct measure and sound physical interpretation naturally, while enabling this framework to permit general numerical discretizations such as with finite elements. In the variational formulation proposed here, we place particular emphasis upon the notion that the scalar function which represents the autonomous total energy of the continuum/N-body dynamical systems can be a crucial mathematical function and physical quantity which is a constant of motion in conservative systems. In addition, we prove that the autonomous total energy possesses the three invariant properties and can be viewed as the so-called total energy version of Noether’s theorem; therefore, the autonomous total energy has time/translational/rotational symmetries for the continuum/N-body dynamical systems. The proposed concepts directly emanating from HLVA inherently involving the scalar function, namely, total energy: (i) can be shown to yield the same governing mathematical model equations of motion that are continuous in space and time together with the natural boundary conditions just as Hamilton’s principle (HP) is routinely used to derive such equations, but without obvious inconsistency via such a principle as explained in the paper; (ii) explain naturally the Bubnov–Galerkin weighted-residual form that is customarily employed for discretization for both space and time, and alternately, (iii) circumvent relying on traditional practices of conducting numerical discretizations starting either from the balance of linear momentum (Newton’s second law) involving Cauchy’s equations of motion (governing equations) arising from continuum mechanics or via (i) and (ii) above if one chooses this option, and instead provides new avenues of discretization for continuum-dynamical systems. The present developments naturally embody the weak form in space and time that can be described by a discrete Total Energy Differential Operator (TEDO). Thereby, a novel yet simple, space-discrete Total Energy formulation proposed here only needs to employ the discrete TEDO which provides new avenues and directly yields the semi-discrete ordinary differential equations in time which can be readily shown to preserve the same physical attributes as the continuous systems for continuum-dynamical applications unlike traditional practices. The modeling of complicated structural dynamical systems such as Euler-Bernoulli beams and Reissner–Mindlin plates is particularly shown here for illustration.     

Electrochemical determination of levofloxacin with a Cu–metal–organic framework derivative electrode

Journal of Materials Science: Materials in Electronics - Levofloxacin (LEV) is used in pharmaceuticals to treat bacterial infections, but is rarely metabolized by the human body, and hence, largely...     

A simulation–optimization framework for short-term underground mine production scheduling

Optimization and Engineering - Mine operations are supported by a short-term production schedule, which defines where and when mining activities are performed. However, deviations can be observed...     

Optimization of the working fluid for a sorption-based Joule–Thomson cooler

Sorption-based Joule–Thomson coolers operate vibration-free, have a potentially long life time, and cause no electromagnetic interference. Therefore, they are appealing to a wide variety of applications, such as cooling of low-noise amplifiers, superconducting electronics, and optical detectors. The required cooling temperature depends on the device to be cooled and extends into the cryogenic range well below 80 K. This paper presents a generalized methodology for optimization in a sorption-based JT cooler. The analysis is based on the inherent properties of the fluids and the adsorbent. By using this method, the working fluid of a JT cooler driven by a single-stage sorption compressor is optimized for two ranges of cold-tip operating temperatures: 65–160 K and 16–38 K. The optimization method is also extended to two-stage compression and specifically nitrogen and carbon monoxide are considered.     

Optimization of the working fluid in a Joule–Thomson cold stage

Vibration-free miniature Joule–Thomson (JT) coolers are of interest for cooling a wide variety of devices, including low-noise amplifiers, semiconducting and superconducting electronics, and small optical detectors used in space applications. For cooling such devices, coolers are needed which have operating temperatures within a wide temperature range of 2–250 K. In this paper, the optimization of the working fluid in JT cold stages is described that operate at different temperatures within that range. For each temperature, the most suitable working fluid is selected on the basis of the coefficient of performance of the cold stage, which is defined as the ratio of the gross cooling power to the change in Gibbs free energy of the fluid during compression. In addition, a figure of merit of the heat exchange in the counter-flow heat exchanger is evaluated that depends only on the properties of the working fluid.     

Optimization of a headspace solid-phase microextraction-gas chromatography–mass spectrometry procedure for odor compounds from polyolefin resin used in plastic food packaging

This research investigated the best headspace solid-phase microextraction (HS-SPME) extraction conditions and used the response surface Box–Behnken trial design to optimize the parameters for the analysis of volatile compounds in polyolefin resin, which is made from powdered polyolefin resin and additives by heating processing. The results showed that when the extraction temperature was 64°C, the extraction time was 34 min, the sample weight was 2.0 g, the testing matrix was air, and the fiber type was 50/30 μm DVB/CAR on PDMS, and the number of volatile compounds in the resin pellets was the highest. The performance characteristics of the optimized method were also determined, and they showed excellent linear ranges, recovery, repeatability, detection, and quantification limits. In the resin pellets and powdered polyolefin resin, the alkane content was the highest, at 585.346 and 581.789 mg/kg, respectively. In the additives, the benzene content was the highest at 39.495 mg/kg. Compounds with odor activity values (OAVs, ratio of concentration to odor threshold) above 1.0 are considered key aroma-active compounds. In total, 135 volatile compounds were identified, and 19 of them had an OAV above 1.0, and 4-methyl-octane and o-xylene were identified as the key odorants in the resin pellets. Only one odorant, 4-methyl-octane, was detected in the powdered polyolefin resin. In the additives, 18 volatile compounds were identified as key aroma-active compounds, such as octanal, nonanal, hexanol, octanol, heptanol, and decanol. The significance of this research was to furnish data to support the further study of odor abatement from food packaging materials.     

Empowering production workers with digitally facilitated knowledge processes – a conceptual framework

Recent digital advancements, including social software, mobile technologies and augmented reality, offer promising opportunities to empower knowledge workers in their production environment by leveraging their knowledge processes, decision-making skills and social interaction practices. This paper proposes a conceptual framework for empowering workers in industrial production environments with digitally facilitated knowledge management processes. The framework explores four concrete facets of digital advancements that apply to a wide range of knowledge processes and production strategies in manufacturing companies. Each of these advancements are capable of supporting one specific facet of the individual knowledge management processes of workers; knowledge transfer, discovery, acquisition and sharing. The study contributes to the production research community by aligning emerging digital technologies and current trends in advanced manufacturing environments to benefit workers and improve job satisfaction, efficiency and productivity. The paper also contains suggestions about developing innovative solutions for production environments that support workers with digital technologies for flexible production.     

Sustainable hydrogen production system with sulfur–water–organic materials by hydrothermal reaction

Engineered process for hydrogen generation from hydrogen sulfide ions in aqueous solution using solar energy with photocatalysis has been established. In order to design a complete closed loop of hydrogen production system, reacted sulfide ions have to be reduced to photocatalysis-active hydrogen sulfide ion. We focused on hydrothermal reaction of sulfur for reducing the reacted sulfide ions. But the oxidized sulfur species are occurred inevitably by the reaction. Thus alternative reducers are required to sulfur hydrothermal reaction for a complete closed loop of hydrogen production system. We studied sulfur–water–organic materials interaction, and particularly on the effective utilization of waste elemental sulfur. In this study, hydrothermal experiments of sulfur, water urea, and/or alcohols were carried out under atmospheric constituent condition and hypoxic condition at 200 °C. Experimental results show that maintaining solution in weak alkaline condition is important and alcohol compounds had a great role for reduction of sulfur. Elemental sulfur was completely reduced to hydrogen sulfide by the hydrothermal reaction of sulfur with urea and propanol under hypoxic condition. Those results indicate that it is possible to create sustainable sulfur cycle for hydrogen production system using hydrothermal reaction with organic compounds.     

Production of a positron beam in the energy range 1–10 MeV

The setup and characteristics of a low energy positron beam at the Giessen linac are desribed. The beam energy can be varied between 1.1 and some MeV. The measured mean positron currents are in the order of some pA within a momentum bin of 0.5%.     

Improving the phase sensitivity of a Mach–Zehnder interferometer via a nonlinear phase shifter

We propose a scheme to improve the phase sensitivity of a Mach–Zehnder interferometer. In this scheme, a Kerr nonlinear phase shifter is used to replace the traditional linear phase shifter. We consider two detection approaches: the direct homodyne detection (DHD) and the indirect homodyne detection (IHD). We find that the Kerr nonlinear phase shifter can improve the phase sensitivity of the interferometer, and the DHD is better than the IHD. In addition, we also find that the phase sensitivity of the Kerr nonlinear interferometer is robust against photon losses.     

Fabrication of nano-macroporous glass–ceramic bioscaffold with a water soluble pore former

Recently, several methods have been reported for fabricating tailored amorphous multi porosity bioscaffolds for bone regeneration and tissue engineering. In particular, the melt-quench-heat-etch method appears attractive for making large and/or complex shape structures or fibers for flexible products. However, often the macropore size has been limited to <100 μm. In this paper we report an improved method for fabricating nano-macroporous soda lime phosphosilicate glass using sucrose as a macropore former. The composite compact consisting of soda lime phosphosilicate glass and sucrose powders is pressed in a die at room temperature. 3D interconnected macroporous structure is formed first by dissolving the sucrose part in water at room temperature, and then sintering the compact at temperatures above the glass transition temperature. Thus, interconnected macropores with controlled size (≥100 microns) are formed readily. The sintering heat-treatment also induces nanoscale phase separation, which is then exploited for introducing nanoscale porosity. For the latter goal, the sample is leached in HCl under optimized conditions to yield desired nano-macroporous glass for bone scaffold or other applications.     

A systems-integration approach to the optimization of macroscopic water desalination and distribution networks: a general framework applied to Qatar’s water resources

The objective of this article is to introduce an optimization-based approach for the integrated design and operation of macroscopic water networks. A structural representation approach is developed to embed all potential configurations of interest. This representation accounts for water resources, desalination plants, water users, wastewater treatment facilities, and storage. Water recycle/reuse is enhanced via the use of treated water. Water utilization is improved by minimizing the losses of discharged water resulting from the linkage of power plants and thermal desalination plants and the lack of integration between water production and consumption. Excess water is saved in storage systems or injected in aquifers for strategic (long-term) storage. The developed approach also accounts for the economic values of water uses and storage and for the cost of water production and allocation. An optimization formulation is developed and solved to determine the optimal operation of the infrastructure. The solution also determines the optimal monthly allocation and storage of water resources. A case study is solved for managing the water resources in the State of Qatar while accounting for desalination, distribution, and storage. The solution indicates that storage in tanks reaches its maximum capacity in less than a month while storage in aquifers continues throughout the year as a strategic step towards water security. The solution also illustrates the need to treat wastewater in addition to using desalination of seawater. The output water streams with different qualities are assigned to proper destinations.     

Facile fabrication of ibuprofen–LDH nanohybrids via a delamination/reassembling process

In this paper, a delamination/reassembling method for the facile fabrication of ibuprofen (IBU), a non-steroidal anti-inflammatory drug, intercalated layered double hydroxide (LDH) nanohybrid was presented. In this method, LDH particles were first delaminated to well dispersed 2D nanosheets in formamide, and then the LDH nanosheets and IBU molecules coassembled into the IBU–LDH nanohybrid. The characteristics of the so-synthesized nanohybrid were the same as that of the IBU–LDH nanohybrids synthesized by the conventional methods including ion exchange, co-precipitation, reconstruction and hydrothermal methods. However, the delamination/reassembling method displayed various remarkable advantages, such as simple procedure, short reaction time, mild condition and high drug loading, compared with the conventional methods.     

Modeling and Optimization of Properties of Domestic Mullite–Corundum Composites

High Temperature - Mathematical modeling of spectral-kinetic, thermal, and electrophysical characteristics, which are difficult to determine experimentally, has been carried out based on the...