Blockchain Papers

Chrıstophe Schınckus

No abstract is available for this record.

Mengjun Chen, Oladele A. Ogunseitan

No abstract is available for this record.

Massimo Pizzol, Romain Sacchi, Susanne Köhler, Annika Anderson Erjavec

Given a fixed product system model, with the current computational framework of Life Cycle Assessment (LCA) the potential environmental impacts associated to demanding one thousand units of a product will be one thousand times larger than what results from demanding 1 unit only – a linear relationship. However, due to economies of scale, industrial synergies, efficiency gains, and system design, activities at different scales will perform differently in terms of life cycle impact – in a non-linear way. This study addresses the issue of using the linear framework of LCA to study scalable and emerging technologies, by looking at different examples where technology scale up reflects non-linearly on the impact of a product. First, a computer simulation applied to an entire database is used to quantitatively estimate the effect of assuming activities in a product system are subject to improvements in efficiency. This provides a theoretical but indicative idea of how much uncertainty can be introduced by non-linear relationships between input values and results at the database level. Then the non-linear relations between the environmental burden per tkm of transport on one end, and the cargo mass and range autonomy on the other end is highlighted using a parametrized LCA model for heavy goods vehicles combined with learning scenarios that reflect different load factors and improvement in battery technology. Finally, a last example explores the case of activities related to the mining of the cryptocurrency Bitcoin, an emerging technology, and how the impact of scaling the Bitcoin mining production is affected non-linearly by factors such as increase in mining efficiency and geographical distribution of miners. The paper concludes by discussing the relation between non-linearity and uncertainty and by providing recommendations for accounting for non-linearity in prospective LCA studies.

Chao Liu, Kok Keong Chai, Xiaoshuai Zhang, Yue Chen

The emergence of blockchain technology brings opportunities for the transactional energy to minimize the time gap and cost in the trading process. This paper proposes a public power exchange service network for Electric Vehicles (EV) to charge and discharge from the power grid. An enhanced novel consensus mechanism Proof-of-Benefit (ePoB) is proposed to improve the protocol security and performance of the electricity exchange system. Furthermore, the benefit number generation algorithm for choosing the leader in the network guarantees the overall power grid network performance by minimizing the load variance. Through theoretical and experimental analysis, the public power exchange system with ePoB consensus protocol achieves higher scalability than Proof- of-Work (PoW) and Paxo-based or BFT-based consensus protocols. Also, it demonstrates that the consensus protocol is capable of withstanding the Sybil attack while achieving lower power load fluctuation level compared with the benchmark.

Yoshinori Hashimoto, Shunya Noda

No abstract is available for this record.

Usman W. Chohan

No abstract is available for this record.

Arda Işıldar

The well-being of the society depends on a number of metals, including base metals, precious metals and increasingly rare earth elements (REE). The usage of these metals increased in numerous applications, including electrical and electronic equipment (EEE), and their interrupted supply is at stake. There is an increasing interest in the secondary sources of these metals, particularly waste electrical and electronic equipment (WEEE) in order to compensate their potential supply deficit. This PhD thesis demonstrates the advantages and bottlenecks of biological and chemical approaches, as well as the advances and perspectives in the development of sustainable processes for metal recovery from WEEE. Furthermore, a novel process for the recovery of metals from WEEE is described, and a techno-economic assessment is given.\nDiscarded printed circuit boards (PCB) from personal computers (PC), laptops, mobile phones and telecom servers were studied. Following an extensive literature review, a novel characterization and total metal assay method was introduced and applied to waste board materials. Discarded PCB contained metals in the range of (%, by weight): copper (Cu) 17.6 - 39.0, iron (Fe) 0.7 - 7.5, aluminum (Al) 1.0 - 5.5, nickel (Ni) 0.2 - 1.1, zinc (Zn) 0.3 - 1.2, as well as gold (Au) (in ppm) 21 - 320. In addition, multi-criteria analysis (MCA) using the analytical hierarchical process (AHP) methodology was applied for selection of the best-suited technology. A proof-of-concept for a two-step bioleaching extraction is given, in which 98.4% and 44.0% of the Cu and Au, respectively, were extracted. The two-step extraction procedure was applied to the chemical leaching of metals from PCB. Cu leaching was carried in an acidic oxidative mixture of H2SO4 and H2O2, whereas Au was leached by S2O32− in a NH4+medium, catalyzed by CuSO4. Under the optimized conditions, 99.2% and 92.2% of Cu and Au, respectively, were extracted from the board material. Selective recovery of Cu from the bioleaching leachate using sulfidic precipitation and electrowinning is studied. Cu was selectively recovered on the cathode electrode at a 50 mA current density in 50 minutes, with a 97.8% efficiency and 65.0% purity. The techno-economic analysis and environmental sustainability assessment of the new technology at an early stage of development was investigated.

Takichi Mitsui

Among the greatest obstacles in the postwar recovery of steel industry in Japan were. counted the shortage of coal, the removal of subvention to the iron and steelprices and -decentralization of large steel firms. A tragic atmosphere thus clouded was pushed away by the breakout of the Korean Incident (June 1950). Again the prices became enhanced. The export was extended and the production increased. Thence came a chance of modernization of iron and steel industry in Japan. The scheme of this plan that had been plotted by the Rationalization Council in the first half of 1951 was encouraged in the second half by establishment of Japan Development Bank, institution of special overeas credit by the Bank of Japan and the favorable development in Capital market.Capital development and production increase of steel firms in Japan was suceessively realized -during the year of 1951. However, towards 1952 the period of reaction began so that an intensification of the sales competition gradually invited a drop in the steel prices, notwith-standing a temporary short boom due to a steel strike in the United States.In April 1952, the industrial control of the Occupation Forces ended and Japan was again allowed to enter an international economic circles.At this moment, owing to establishment of the European Coal and Steel Community, progress of modernization progress in several countries and recovery of the West-Germany iron and steel industry, the steel industry of Japan too was obliged to be entangled with the international contest.In 1953, the steel market again tended to a slight boom due to domestic investment and consumption but at the end of the same year decrease in bath munition demands and steel export again occurred. Without finding domestic demands, the steel products of Japan began to flow out overseas. At this time happily owing to a shortage of steel export from Europe Japanese products filled the markets of South America and India and enjoyed higher prices. It was also evident at the end of 1954 that the iron and steel industry in rapan again inclined to an expansive production.After such historical introduction, the author described in detail (1) the process of rationalization and financing concerned; (2) trends in the situations of raw materials for iron and steel; (3) domestic market and export; (4) some tendencies in special steels; and (5) future prospects.