As agroindústrias familiar rural surgem a partir de sonhos empreendedores ou como forma de agregar valor para melhorar a renda. Esta pesquisa teve como objetivo analisar a viabilidade econômica e o ...custo de produção de um empreendimento agroindustrial familiar da região Central de Rondônia. Para tal, elaborou-se um instrumental, tendo como base o princípio da ferramenta FOFA, fez-se oficinas participativas e análise de materiais secundários. O custo da construção representou 36,9%. Já aquisição dos equipamentos e veículo utilitário representou 49,9% dos investimentos. Já o principal item do custo variável é o leite, principal matéria prima com 22,7%. Neste sentido, para produzir um litro de leite pasteurizado, o custo fixo de R$ 0,41, o variável de R$ 2,67 totalizando R$ 3,08 que gera um prejuízo de 6,5%, pois é comercializando à R$ 2,88. Já o iogurte, tem custo fixo de R$ 0,44, o variável de R$ 4,30 totalizando R$ 4,74 que gera um lucro de 43,5%, pois é comercializando à R$ 6,80. Conclui-se que a agroindústria é de pequeno porte, com pequena escala de produção, atendendo o mercado local, com parâmetros rígidos de controle sanitário, de acordo com o PROVE/RO e a produção se dá com uso de tecnologias. Quanto à gestão, encontram-se dificuldades em controlar os custos de produção. Diante disso, fica evidente que a produção agroindustrial necessita de gestão profissionalizada, ou seja, os produtores devem buscar formação para melhor controle de sua atividade, otimizando os recursos de modo a garantir a sustentabilidade do empreendimento.
The existing literature on the construction costs of nuclear power reactors has focused almost exclusively on trends in construction costs in only two countries, the United States and France, and ...during two decades, the 1970s and 1980s. These analyses, Koomey and Hultman (2007); Grubler (2010), and Escobar-Rangel and Lévêque (2015), study only 26% of reactors built globally between 1960 and 2010, providing an incomplete picture of the economic evolution of nuclear power construction. This study curates historical reactor-specific overnight construction cost (OCC) data that broaden the scope of study substantially, covering the full cost history for 349 reactors in the US, France, Canada, West Germany, Japan, India, and South Korea, encompassing 58% of all reactors built globally. We find that trends in costs have varied significantly in magnitude and in structure by era, country, and experience. In contrast to the rapid cost escalation that characterized nuclear construction in the United States, we find evidence of much milder cost escalation in many countries, including absolute cost declines in some countries and specific eras. Our new findings suggest that there is no inherent cost escalation trend associated with nuclear technology.
•Comprehensive analysis of nuclear power construction cost experience.•Coverage for early and recent reactors in seven countries.•International comparisons and re-evaluation of learning.•Cost trends vary by country and era; some experience cost stability or decline.
A vision is presented on 3D printing with concrete, considering technical, economic and environmental aspects. Although several showcases of 3D printed concrete structures are available worldwide, ...many challenges remain at the technical and processing level. Currently available high-performance cement-based materials cannot be directly 3D printed, because of inadequate rheological and stiffening properties. Active rheology control (ARC) and active stiffening control (ASC) will provide new ways of extending the material palette for 3D printing applications. From an economic point of view, digitally manufactured concrete (DFC) will induce changes in the stakeholders as well as in the cost structure. Although it is currently too ambitious to quantitatively present the cost structure, DFC presents many potential opportunities to increase cost-effectiveness of construction processes. The environmental impact of 3D printing with concrete has to be seen in relation to the shape complexity of the structure. Implementing structural optimization as well as functional hybridization as design strategies allows the use of material only where is structurally or functionally needed. This design optimization increases shape complexity, but also reduces material use in DFC. As a result, it is expected that for structures with the same functionality, DFC will environmentally perform better over the entire service life in comparison with conventionally produced concrete structures.
The problem of providing privacy, in the private information retrieval (PIR) sense, to users requesting data from a distributed storage system (DSS), is considered. The DSS is coded by an ...<inline-formula> <tex-math notation="LaTeX">(n,k,d) </tex-math></inline-formula> maximum distance separable code to store the data reliably on unreliable storage nodes. Some of these nodes can be spies which report to a third party, such as an oppressive regime, which data is being requested by the user. An information theoretic PIR scheme ensures that a user can satisfy its request while revealing no information on which data is being requested to the nodes. A user can trivially achieve PIR by downloading all the data in the DSS. However, this is not a feasible solution due to its high communication cost. We construct PIR schemes with low download communication cost. When there is <inline-formula> <tex-math notation="LaTeX">b=1 </tex-math></inline-formula> spy node in the DSS, in other words, no collusion between the nodes, we construct PIR schemes with download cost <inline-formula> <tex-math notation="LaTeX">\frac {1}{1-R} </tex-math></inline-formula> per unit of requested data (<inline-formula> <tex-math notation="LaTeX">R=k/n </tex-math></inline-formula> is the code rate), achieving the information theoretic limit for linear schemes. The proposed schemes are universal since they depend on the code rate, but not on the generator matrix of the code. Also, if <inline-formula> <tex-math notation="LaTeX">b\leq n-\delta k </tex-math></inline-formula> nodes collude, with <inline-formula> <tex-math notation="LaTeX">\delta =\lfloor {\frac {n-b}{k}}\rfloor </tex-math></inline-formula>, we construct linear PIR schemes with download cost <inline-formula> <tex-math notation="LaTeX">\frac {b+\delta k}{\delta } </tex-math></inline-formula>.
Earth orbiting satellites come in a wide range of shapes and sizes to meet a diverse variety of uses and applications. Large satellites with masses over 1000 kg support high-resolution remote sensing ...of the Earth, high bandwidth communications services, and world-class scientific studies but take lengthy developments and are costly to build and launch. The advent of commercially available, high-volume, and hence low-cost microelectronics has enabled a different approach through miniaturization. This results in physically far smaller satellites that dramatically reduce timescales and costs and that are able to provide operational and commercially viable services. This paper charts the evolution and rise of small satellites from being an early curiosity with limited utility through to the present where small satellites are a key element of modern space capabilities.
We show how to build a multiscale entanglement renormalization ansatz (MERA) representation of the ground state of a many-body Hamiltonian H by applying the recently proposed tensor network ...renormalization G. Evenbly and G. Vidal, Phys. Rev. Lett. 115, 180405 (2015) to the Euclidean time evolution operator e(-βH) for infinite β. This approach bypasses the costly energy minimization of previous MERA algorithms and, when applied to finite inverse temperature β, produces a MERA representation of a thermal Gibbs state. Our construction endows tensor network renormalization with a renormalization group flow in the space of wave functions and Hamiltonians (and not merely in the more abstract space of tensors) and extends the MERA formalism to classical statistical systems.
Hydrogen (H2) is a promising alternative energy carrier because of its environmental benefits, high energy density, and abundance. However, development of a practical storage system to enable the ...“Hydrogen Economy” remains a huge challenge. Metal–organic frameworks (MOFs) are an important class of crystalline coordination polymers constructed by bridging metal centers with organic linkers. MOFs show promise for H2 storage owing to their high surface area and tuneable properties. In this Account, we summarize our research on novel porous materials with enhanced H2 storage properties and describe frameworks derived from 3,5-substituted dicarboxylates (isophthalates) that serve as versatile molecular building blocks for the construction of a range of interesting coordination polymers with Cu(II) ions. We synthesized a series of materials by connecting linear tetracarboxylate linkers to {Cu(II)2} paddlewheel moieties. These materials exhibit high structural stability and permanent porosity. Varying the organic linker modulates the pore size, geometry, and functionality to control the overall H2 adsorption. Our top-performing material in this series has a H2 storage capacity of 77.8 mg g–1 at 77 K, 60 bar. H2 adsorption at low, medium, and high pressures correlates with the isosteric heat of adsorption, surface area, and pore volume, respectively. Another series, using tribranched C 3-symmetric hexacarboxylate ligands with Cu(II), gives highly porous (3,24)-connected frameworks incorporating {Cu(II)2} paddlewheels. Increasing the length of the hexacarboxylate struts directly tunes the porosity of the resultant material from micro- to mesoporosity. These materials show exceptionally high H2 uptakes owing to their high surface area and pore volume. The first member of this family reported adsorbs 111 mg g–1 of H2, or 55.9 g L–1, at 77 K, 77 bar, while at 77 K, 1 bar, the material adsorbs 2.3 wt % H2. We and others have since achieved enhanced H2 adsorption in these frameworks using combinations of polyphenyl groups linked by alkynes. The maximum storage achieved for one of the enhanced materials is 164 mg g–1 at 77 K, 70 bar, but because of its low density, its volumetric capacity is only 45.7 g L–1. We attribute the significant adsorption of H2 at low pressures to the arrangement of the {Cu24(isophthalate)24} cuboctahedral cages within the polyhedral structure. Free metal coordination positions are the first binding sites for D2, and these frameworks have two types of Cu(II) centers, one with its vacant site pointing into the cuboctahedral cage and another pointing externally. D2 molecules bind first at the former position and then at the external open metal sites. Design of ligands and complexes is key for enhancing and maximizing H2 storage, and although current materials operate at 77 K, research continues to explore routes to high capacity H2 storage materials that can function at higher temperatures.
Not surprisingly, with the increased awareness of environmental issues, construction with raw (crude, unbaked) earth (subsoil) is gaining renewed interest. However, it suffers from a poor image and ...from the difficulty to meet modern productivity standards and to pass some durability tests designed for industrial materials. The recent trend is to overcome these drawbacks by “stabilizing” the material most often with Portland cement (PC). Here we show that stabilization with PC is in general neither technically nor environmentally advisable. It brings only moderate mechanical improvement at a high environmental cost. Rather than massively transforming crude earth into a low quality concrete, it would be more appropriate to adapt the architectural practice and/or to look for milder ways to improve properties. In this respect, the recent successful attempts to improve the workability and the strength of raw earth by controlling the dispersion of its fine fraction seem to be particularly promising.
The cost-effective construction of self-designed conductive graphene patterns on desired substrates is crucial to the fabrication of graphene-based electrochemical devices. Here, we report a new ...approach for the scalable construction of laser-induced graphene (LIG) patterns on diverse substrates by using phenolic resin (PR) as the precursor. The PR-based LIG, which was produced with smart and inexpensive 405 nm semiconductor lasers under ambient conditions, possesses several interesting properties, e.g., 3D porous structures, low resistance (∼44 Ω/sq), good mechanical property and a wide range of applicable substrates, e.g., polymer films, glass slides, metal foils, ceramic plates and plant leaves. The efficient absorption of laser light by PR coatings themselves or dopants such as metal salts and organic dyes is demonstrated critical to the formation of PR-based LIG by visible light lasers. Based on this technique, self-designed and highly conductive graphene arrays can be easily constructed on various substrates to fabricate all-carbon supercapacitors and electrochemical glucose biosensors. The unique properties of PR materials, including easy synthesis, tunable structure and composition, excellent film-formation ability and extremely low cost, thus foresee the promising applications of PR-based LIG in electrochemical fields.
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