Agroecology and the conversion of lárge‐scale conventional systems to sustainable management

This paper describes the agroecological principles necessary to guide the conversion of high‐input conventional systems to a low‐input management based on crop diversification and livestook integration schemes which break the monoculture nature of conventional systems. The new crop‐crop and crop‐animal combinations result in a series of synergisms and complementarities among farming system components which lead to optimal recycling of organic matter and nutrients, and to balanced pest‐natural enemy populations. Thus, agroecological design goes beyond “input‐substitution” by establishing systems capable of sponsoring their own soil fertility, crop protection and yield constancy. These new agroecosystems provide a sustainable level of productivity with minimal need for external (conventional or organic) resources. Biological structuring sponsors the functioning of the system.     

Evaluating the deterioration of electrodes when increasing the number of pulses in the welding time using galvanised IF and HSLA steels and assigning mechanical properties in the spot welds

ABSTRACT

Resistance spot welding is the most important method in the industry of self-supporting or monocoque body joinery because of its automation, its speed, the flexibility of welding parts with a complicated shape, and it is economical because it does not require a filler metal, and it is also possible to apply pre-heating and post-heating pulses to improve the weldability of the spot weld, which is defined as the ability of the structure to adequately protect passengers against injuries in the event of a collision, and this mainly depends on the integrity and mechanical performance of the weld button. In order to extend the lifetime of vehicles, galvanized steels are produced. However, zinc coatings have increased the difficulty of weldability, with higher currents being required in the process, since there is less resistance at the weld interface due to improved electrical conductivity. This work investigates the effect of galvanizing on the reduction of the lifetime of the electrodes, for this reason, it follows that there is a loss in the mechanical properties in the weld buttons as the number of spot welds increases. The main aim of this study is to correlate the electrode wear with the mechanical properties of the weld buttons. The experiment procedure consists of making 1,000 spot welds; and every twenty-fifth spot weld after the first was examined by means of stereoscopy, hardness tests, unbuttoning tests and shear stress tests. In terms of electrode wear, the face was evaluated using impressions on carbon paper, optical microscopy and X-ray spectroscopy.     

Formation of Colloidal Shells on Acidic Droplets Undergoing Neutralization in Marine Diesel Engine Cylinder Oils

In this study, a novel colloidal shell formation phenomenon was observed when sulfuric acid droplets underwent neutralization in marine cylinder lubricant at 115 ± 5 °C using heating microcapillary videomicroscopy. Immediately upon injection, shells formed, wrapping the acidic droplets and detached slowly afterward. Shells were optically transparent, about 2 μm thick, and strongly cohesive and rigid since they could deform the contained acid droplet into a non-spherical shape. Shell surface is most likely hydrophobic since the acid droplets did not wet it. It is thought that these shells were made of hydrated calcium sulfate nanoparticles embedded within an organic matrix. This material was presumably formed when oil additives reacted with sulfuric acid right upon exposure. The discovery of this shell formation, which has not been previously reported in the literature, could be important since these shells could be precursors in the formation of well-known deposits found in diesel engine cylinder liners such as “liner lacquer” or “bore glaze,” which impact negatively the performance of marine diesel engines.     

Assessment of data-driven modeling strategies for water delivery canals

The aim of this paper is to develop models for experimental open-channel water delivery systems and assess the use of three data-driven modeling tools toward that end. Water delivery canals are nonlinear dynamical systems and thus should be modeled to meet given operational requirements while capturing all relevant dynamics, including transport delays. Typically, the derivation of first principle models for open-channel systems is based on the use of Saint–Venant equations for shallow water, which is a time-consuming task and demands for specific expertise. The present paper proposes and assesses the use of three data-driven modeling tools: artificial neural networks, composite local linear models and fuzzy systems. The canal from Hydraulics and Canal Control Nucleus (Évora University, Portugal) will be used as a benchmark: The models are identified using data collected from the experimental facility, and then their performances are assessed based on suitable validation criterion. The performance of all models is compared among each other and against the experimental data to show the effectiveness of such tools to capture all significant dynamics within the canal system and, therefore, provide accurate nonlinear models that can be used for simulation or control. The models are available upon request to the authors.     

Distilling the salient features of natural systems: Commentary on “On the mapping of genotype to phenotype in evolutionary algorithms” by Whigham,Dick and Maclaurin

Here we comment on the article, “On the mapping of genotype to phenotype in evolutionary algorithms”, by Peter A. Whigham, Grant Dick, and James Maclaurin. The authors present a critical view on the use of genotype to phenotype mapping in Evolutionary Algorithms, and how the use of this analogy can be detrimental for problem solving. They examine a grammar-based approach to Genetic Programming (GP), Grammatical Evolution (GE), and highlight properties of GE which are detrimental to effective evolutionary search. Rather than use loose analogies and methaphors, we suggest that a focus should be (and has been in GE and other approaches to GP) on addressing one of the most significant open issues in our field, i.e., What are the sufficient set of features in natural, genetic, evolutionary and developmental systems, which can translate into the most effective computational approaches for program synthesis?     

Emergence of modern scientific discourse in the American continent: knowledge claims in the discovery of Erythronium/Vanadium in Mexico (1802–1832)

In the present paper, we study the discovery of the chemical element number 23, Erythronium/Vanadium (E/V), as an early example of the modern process of validating knowledge claims in México. We examined the published work between 1802 and 1832 of Andrés Manuel del Río (AMR) in the Royal Mining Seminar of México and contrasted the styles of argument and forms of certification between his teaching and experimental writings concerning his claim to the paternity of E/V discovery. We also analyze the respective papers of European authors that replicated, rediscovered and certified AMR’s finding. We use a combination of bibliometric, sociotechnical network and literary critical analysis in order to show that the certification of E/V spawned an emerging mode for producing and validating new knowledge in the American continent and particularly in México. In turn, this approach supports AMR’s claim to the discovery of E/V from the production process of the lead brown ore in Zimapán, México.

     

A comparison of different approaches for depth profiling of films and coatings by confocal Raman microscopy

We compare and analyze different approaches to perform depth profiling of polymer films and coatings by confocal Raman microscopy (CRM). Data were generated using three methodologies: conventional metallurgical objectives, oil-immersion optics and numerical post processing of the as-measured intensity profiles, via an optimized deconvolution technique adapted to CRM. A series of bi- and multi-layered polymeric films were used as test systems. Strengths and weaknesses of each methodology are evaluated in terms of delivered depth resolution, signal throughput and flexibility. It is shown that the application of regularized deconvolution on data obtained from dry objectives yielded intensity profiles with a quality comparable, in some cases superior, to those obtained with immersion objectives, with the advantage of being totally non-invasive.     

Neoformation of antioxidants in glycation model systems treated under subcritical water extraction conditions

In this work, the possibility of finding newly formed Maillard reaction products produced as a result of the subcritical water extraction (SWE) conditions is explored. Simplified powdered glycation model systems were prepared mixing amino acid (Lys, Arg or Ala) and glucose in a molar ratio 1:4. Samples constituted by glucose or amino acids alone were also prepared as controls. SWE was carried out at room temperature, 100 °C and 200 °C and 100 bar of pressure for 20 min. Different assays were performed in order to determine the extent of glycation by analyzing the decrease of free amino groups and/or the formation of Maillard reaction products (early, advanced and end products). Namely, formation of early colorless Maillard reaction products, Amadori compounds, was detected by ESI-MS; advanced glycation end products (AGEs) were detected by measuring the fluorescence intensity (λ_ex = 360 nm, λ_em = 460 nm) while end brown products were detected by reading the absorbance at 360 and 420 nm. Besides, the antioxidant capacity of the aqueous extracts was determined by using ABTS and ORAC_FL assays. Results obtained indicated the occurrence of the Maillard reaction under our specific extraction conditions. Early, advanced and end products were detected in the samples. Caramelization of sugar also occurred. As expected, the extent of the non-enzymatic browning depended on the intensity of the thermal treatment. Additionally, data on antioxidant activity suggested the formation of neoantioxidants. These compounds were predominantly formed at 200 °C. In conclusion, this report demonstrates the formation of antioxidant compounds in simplified glycation model systems under SWE conditions.     

碎裂的城市塞维利亚 对1992年世博后的思考

位于欧洲南部中等规模的城市塞维利亚曾分别在1929年与1992年举办过两次重要的国际性博览会,博览会不仅塑造了当下的城市形状,且通过加强通信设施与基础建设转变了城市与整个区域的关系。作为城市发展的捷径,这些大事件能加快发展并有机会通过连贯统一的提案重塑城市,避免长期通用的总体规划带来一系列问题。塞维利亚面对一条需要恢复水体环境的河流,并将成为新的城市节点。然而经过20年,世博会场址仍然与城市其他部分相隔离。该区域城市功能的设置缺失居住和商业,使其置于深度破碎的境地;被包裹的簇团必然将城市区域撕裂开来。这里是碎裂的城市。