On the mobile‐to‐mobile linear time‐variant shallow‐water acoustic channel response

We expose some concepts concerning the channel impulse response (CIR) of linear time‐varying (LTV) channels to give a proper characterization of the mobile‐to‐mobile underwater channel. We find different connections between the linear time‐invariant (LTI) CIR of the static channel and 2 definitions of LTV CIRs of the dynamic mobile‐to‐mobile channel. These connections are useful to design a dynamic channel simulator from the static channel models available in the literature. Such feature is particularly interesting for overspread channels, which are hard to characterize by a measuring campaign. Specifically, the shallow water acoustic (SWA) channel is potentially overspread because of the signal low velocity of propagation, which prompts long delay spread responses and great Doppler effect. Furthermore, from these connections between the LTI static CIRs and the LTV dynamic CIRs, we find that the SWA mobile‐to‐mobile CIR does not only depend on the relative speed between transceivers, but also on the absolute speed of each of them referred to the velocity of propagation. Nevertheless, publications about this topic do not consider it and formulate their equations in terms of the relative speed between transceivers. We illustrate our find using 2 couples of examples where, even though the relative speed between the mobiles is the same, their CIRs are not.     

PyDTNN: A user-friendly and extensible framework for distributed deep learning

The Journal of Supercomputing - We introduce a framework for training deep neural networks on clusters of computers with the following appealing properties: (1) It is developed in Python, exposing...     

A Modelling Approach to Forecast the Effect of Climate Change on the Tagus-Segura Interbasin Water Transfer

This study was conducted in the upper Tagus River basin (UTRB), whose available water resources are partially transferred from the Entrepeñas and Buendía reservoirs after local needs satisfaction to the Segura River basin using the Tagus-Segura water transfer (TSWT), the largest hydraulic infrastructure in Spain. This study evaluates the climate change impact on the TSWT by considering future evaporation rates and bathymetric changes in the Entrepeñas and Buendía reservoirs. The findings of this study indicate a consistent decline in precipitation and an increase in temperature and evaporation under all climate impact scenarios. Consequently, inflows to the reservoirs will decline by 19% (RCP 4.5) and 53% (RCP 8.5) for 2070–2099, which could reduce water volumes that could be transferred to the Segura basin by more than 60%. The simulation of the TSWT operation rules, taking into account the impact of future evaporation and bathymetric changes, demonstrates an additional increase in reductions of water transfer of around 4%, which reveals the need to consider these effects in hydrological planning.

     

Oxidative Stability and Characterization of Quinoa Oil Extracted from Wholemeal and Germ Flours

Quinoa seeds are a source of lipids of great quality, and they highlight the content and composition of fatty acids and the presence of antioxidants such as tocopherols. Solvent extraction of quinoa oils was carried out from two matrices (wholemeal and germ flours), and in both cases, the extraction performance, physical–chemical characteristics, and oxidative stability were determined. Oxidative stability of the oil was assessed using an accelerated aging experiment under storage conditions at 60 °C for 12 days, in which the following parameters were measured: peroxide value, acid value, conjugated dienes and trienes, and scavenging radical capacity. Germ flour showed greater extraction yields (27.30 ± 0.15 g/100 g) compared to wholemeal (5.88 ± 0.02 g/100 g). Both oils presented similar physicochemical parameters, although the tocopherol content was higher in the oil extracted from germ flour (1354 vs. 735 mg/kg oil). At the same time, wholemeal oil showed a superior oxidative stability; hence, the wet milled process produces a minor impact on the compounds responsible for protection against lipid oxidation.     

Influential Factors in the Synthesis of Polymethylhydrogenosiloxane Obtained via Cationic Ring-Opening Polymerization Using Synthetic Silica-Aluminates as Catalysts

In the ambit of the synthesis of silicon polymers and elastomers, there are a lot of variables that affect the final properties of the material, and consequently, their applications. In this work, we synthetized polymethylhydrogensiloxane using the ring opening polymerization (ROP) with 2,4,6,8-tetramethylcyclotetrasiloxane as monomer (D₄^H), a synthetic aluminosilicate like catalytic species and hexamethyldisiloxane as chain blocker. We made a set of experiments, in order to find the effect on the reaction yield, the absence of crosslinking, crosslinking degree and the mechanical properties of the final polymers. We found that the factor “chain blocker addition time” is significant for yield reaction and crosslinking degree of the elastomers, obtaining a greater crosslinking degree and reaction yield when is added at the beginning of the reaction. Also, using DSC measurements, we found an endothermal signal in 553 K corresponding to the elastomer’s chains rearrangement to dissipate the heat supplied. We obtained PMHS chains up to 24,270 g/mol indicating the ability of this kind of catalysts to achieve relatively high molecular weight chains.

     

Integrated decision support framework for distribution network design

In the current business environment of competition shifting from company-to-company to supply chain against supply chain, there is an increasing need for logistics providers (LSP) to gain cost effectiveness with no compromise on service levels. One key initiative that LSP can undertake is to allocate and utilise their storage and transportation assets optimally. The current work is an attempt in that direction and provides a hands-on decision support framework that integrates MCDM, network optimisation, and discrete event simulation to address distribution network design and transport optimisation. The use case of PT Pos Indonesia in the metropolitan area of Greater Surabaya highlights the benefits of combining ICT tools with well-established best practices in supply chain management. Findings of this work highlight that the number of distribution facilities for the case at hand should be reduced from nine to four. Compared to the existing, the identified network configuration unlocks potential cost saving in transportation and warehousing of 18%–22%, reduces CO₂ emissions by nearly 30%, with no deterioration in service level. Managerial implications about transportation policies are highlighted in the conclusive part of this paper.     

Studies on the effect of long-chain and head groups of nonionic surfactants synthesized from palm and coconut oil on the formation of silver nanoparticles

Four fatty amides were synthesized using coconut and palm oil sources. The chemical structure of the as-prepared fatty acids was confirmed using Fourier Transform Infrared (FT-IR) and ¹H, ¹³C NMR spectroscopy. The effect of different chain lengths and head groups of these compounds on Ag nanoparticles (NPs) synthesis was investigated. Ultraviolet–visible spectroscopic studies showed characteristic absorbance peaks (λ_max ≈ 410 nm). FT-IR results indicated that the surfactant functionalities are responsible for the Ag NPs stability. The effect of fatty amides on the morphology and size distribution of the Ag NPs was investigated using transmission electron microscope (TEM). The TEM micrographs showed the formation of fine spherical morphology due to surfactant-mediated self-assembly with an average particle size of 1–3 nm. Dynamic light scattering (DLS) analysis showed the micellar self-assembly of Ag NPs-fatty amides. The effect of surfactant on the solution behavior was analyzed using surface tension measurements. Cocamide and palm DEA showed relatively low free energy (∆G_mic) values, resulting in smaller particles with good distribution. Finally, the Ag NPs showed outstanding antimicrobial activity against Pseudomonas putida bacteria.     

Invited review: Effect of antihypertensive fermented milks on gut microbiota

Hypertension is a risk factor for the development of other cardiovascular diseases and remains one of the leading causes of death worldwide. Although genetic and environmental factors are associated with the development of hypertension, it has been recently recognized that gut microbiota (GM) may also have an effect on human health. In this sense, gut dysbiosis (a marked decrease in richness and diversity of GM) has been linked to different metabolic diseases, such as hypertension. Therefore, different studies have been pursued to reduce gut dysbiosis and diminish hypertension. Different strategies to maintain a balanced GM, particularly through diet and the use of probiotics, are being evaluated. Most recently, the effect of antihypertensive fermented milks on GM has been addressed. New evidence suggests that antihypertensive fermented milks may modulate GM. Thus, the aim of this review is to present available information related to the effect of antihypertensive fermented milks on gut microbiota.     

The semiotics of landscape design communication: towards a critical visual research approach in landscape architecture

In landscape architecture, visual representations are the primary means of communication between stakeholders in design processes. Despite the reliance on visual representations, little critical research has been undertaken by landscape architects on how visual communication forms work or their socio-political implications. In this theoretical paper, we argue that such research is of great importance. We explain how concepts of visual and critical social theory such as visual semiotics, simulacra and simulation, and power/knowledge can be used to critically reflect on landscape architectural representations. We further propose to study these representations at different stages of meaning-making by using visual methodologies such as visual discourse analysis, iconographical content analysis and social semiotic analysis. We conclude that these research approaches have the potential to explain issues such as dominant power structures, miscommunication between participants, and visual path-dependencies during landscape design processes.