The cross wire projection welding of wires (Al 5182, = 4 mm) performed using the conventional (i.e. pneumatic) electrode force system was subjected to thorough numerical analysis. Calculations were performed until one of adopted boundary conditions, i.e., maximum welding time, maximum penetration of wires, the occurrence of expulsion or the exceeding of the temperature limit in the contact between the electrode and the welded material was obtained. It was observed that the ring weld was formed within the entire range of welding parameters. The process of welding was subjected to optimisation through the application of a new electromechanical electrode force system and the use of a special hybrid algorithm of electrode force and/or displacement control. Comparative numerical calculations were performed (using SORPAS software) for both electrode force systems. Technological welding tests were performed using inverter welding machines (1 kHz) provided with various electrode force systems. The research also involved the performance of metallographic and strength (peeling) tests as well as measurements of welding process characteristic parameters (welding current and voltage).
The welding process optimisation involving the use of the electromechanical force system and the application of the hybrid algorithm of force control resulted in i) more favourable space distribution of welding power, ii) energy concentration in the central zone of the weld, iii) favourable (desired) melting of the material within the entire weld transcrystallisation zone and iv) obtainment of a full weld nugget.
BiVO4 was hydrothermally synthesized under different preparing conditions and characterized by XRD, SEM, Raman spectrum and BET specific surface area. The influence of different pH value and annealing temperature and hydrothermal time on the morphologies and structures of the BiVO4 samples was investigated systematically. It can be found that annealing would eliminate the effects caused by the pH of precursor, heating temperature and heating time, but preparing conditions still influenced the size and specific surface area of samples. Furthermore, the photocatalytic activities of the fabricated BiVO4 were also evaluated by the degradation of methyl blue in aqueous solution under UV and visible light irradiation.
The market demand for uniformity and productivity of commercial carrot roots has prioritized hybrid materials over open-pollinated varieties. In this sense, the objective of this work was to estimate the combining ability of carrot genitors for root productivity and resistance to leaf scorch. The experiments were conducted in Gama, DF, in the agricultural years 2012/13 and 2013/14. We evaluated 33 carrot hybrids, originated from crosses between three male-sterile populations, with 11 male-fertile S2 lines, all the genitors being of tropical origin. At 90 days after sowing, the severity of the leaf blight disease was estimated in the plots. At 100 days after sowing, harvesting was performed and root yield characters were evaluated. Analysis of variance and partial diallel analysis were performed for each year and jointly for both years. It was found that additive and non-additive genes are important in the manifestation of root yield and leaf blight resistance traits in carrot hybrids. The male-sterile parents with higher overall combining ability for root productivity are strains LM-649 and LM-650 and, among the male-fertile, strain LM-555-2-2. The best hybrids for root yield and leaf blight resistance are LM-649 × LM-555-11-1, LM-650 × LM-555-7-1 and LM-650 × LM-554-8-1.
Nothofagus pumilio forests constitute the most economically important forest stand in southern Argentina and Chile. Total volume stocking and volumetric yield vary according to site quality, degree of occupation, growth stage and forest history of the stand. The objective of this work was to evaluate the stocking and the productive potential in quantity and quality of products for the sawmilling industry, using three harvesting systems (short logs, long logs and complete shafts) in the protection cut of a N. pumilio forest of site quality III in Tierra del Fuego (Argentina). The trials were conducted in an irregular mature forest with two strata and abundant regeneration (3.0 ha; RDI 93.8–113.4%). Total volumes varied between 726.5 and 850.3 m3∙ha-1, with a volume/basal area ratio of 11.8 to 12.1 m3∙m-2. The harvesting rates obtained were: 45.5% for complete logs, 21.3% for long logs and 22.4% for short logs. A model was used to estimate the timber volume for each system, where full shafts resulted in a significant increase in timber volume. Considering new alternatives in the planning of harvesting in forest management for N. pumilio forests, such as the system of complete shafts, allows obtaining higher harvesting rates, increasing the benefits for the forestry company and minimizing the damage to the forest, due to the shorter distance of the machinery in the forest harvesting.
Using a newly-developed data set for Portugal, we analyze the industry-level effects of infrastructure investment. Focusing on the divide between traded and non-traded industries, we find that infrastructure investments have a non-traded bias, as these shift the industry mix towards private and public services. We also find that the industries that benefit the most in relative terms are all non-traded: construction, trade, and real estate, among the private services, and education and health, among the public services. Similarly, emerging trading sectors, such as hospitality and professional services, stand to gain. The positive impacts on traded industries are too small to make a difference. These results highlight that infrastructure-based strategies are not neutral in terms of the industry mix. Moreover, with most of the benefits accruing to non-traded industries, such a development model that is heavily based on domestic demand may be unsustainable in light of Portugal’s current foreign account position.
While there has been much discussion about the large infrastructure needs in Asia and the Pacific, less attention has been paid to public expenditure efficiency in infrastructure services delivery. New constructions are not the only solution, especially when governments have limited capital to invest. Globally, new infrastructure projects face delays and cost overruns, leading to an inefficient use of public resources. The root causes include the lack of transparency in project selection, the lack of project preparation, the silo approach by public entities in assessing feasibility studies, and the lack of public sector capacity to fully develop a bankable pipeline of projects. To tackle these issues, governments need a smarter investment approach and to do so, enhancing public service efficiency is very crucial. The paper suggests a “whole life cycle” (WLC) approach as the main strategic solution for the discussed issues and challenges. We expand the definition of WLC to include the entire life cycle of the infrastructure asset from need identification to its disposal. The stages comprise planning, preparation, procurement, design, construction, operation and maintenance, and disposal. This is because we believe any efficient or inefficient decision throughout such a wide life cycle influences the quality of public services. Hence, in this holistic approach, infrastructure life cycle consists of four phases: planning, preparation, procurement, and implementation. Governments could enhance public efficiency and thus improve access to finance throughout the WLC by several solutions. These are (i) preparing infrastructure master plan and pipelines and long-term budgeting during the planning phase; (ii) establishing framework and guidelines and improving governance during preparation phase; (iii) promoting standardization, transparency, open government, and contractual consistency during the procurement phase; and finally (iv) continued role of government and total asset management during the implementation phase. In addition to these phase-specific means, key WLC solutions include proper use of technology, capacity building, and private participation in general and public-private partnership (PPP) in particular.
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