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This paper presents a new analytical design method of passive harmonic filter for industrial process application using a transfer function approach and provides a graphical formulation so that a visualised insight into an interaction between individual filter and system response can be attained. Harmonic impedance, voltage division and current division transfer function are used as a design tool, which makes calculated filter parameters to satisfy IEEE-519 requirements. A simple six-step design procedure is introduced in the filter design and the procedure includes measurement analysis on system, selection of filter location (PCC), calculation of filter specification, decision of tuning order, filter design for system and fit filter to system. Principle of the design procedure is based on a numerical/graphical iterative solution as well as trial and error with visualisation feed-back using 'algebra on the graph'. Finally, performance of the designed passive harmonic filter is evaluated in experiment and the result shows that 5th, 7th, 11th and 13th harmonics are decreased within IEEE-519 requirements, respectively.

Soil is a fundamental part of successful agriculture, and its quality has to be improved to maximize crop yield and soil fertility. To increase crop productivity and soil fertility, biochar can be applied to the soil. Biochar is a solid carbon-rich product produced from biomass of agricultural crop residues, wastes, and wood, through pyrolysis in an oxygen-deficient condition. Carbon sequestration through biochar is important because of its potential applications in recycling wastes, retaining nutrients in the soil and lowering greenhouse gas emissions. In this review, we explore the various applications of biochar to ensure the safe and sustainable improvement of soil fertility. This review provides an overview of biochar properties, production technology, and its employment in the agriculture. This review would be a useful resource for researchers, farmers, and academics who are interested in the utilization of biochar.

As environmental and energy issues continue to emerge as global concerns, Leadership in Energy and Environmental Design (LEED) certification is becoming highly valued. However, since additional costs for LEED certification cannot be estimated before proceeding with certification projects, financial losses are often incurred. Additional construction costs are the most significant issue faced by enterprises aiming for LEED certification. Rough estimates of the range of additional construction costs are available, but it is difficult to identify factors that increase or decrease the price of a building. Thus, there is a need for a program that provides average data for LEED certification costs and suggests the easiest way to attain credits for a building. Considering that LEED certification is a rating system, this study develops an optimization algorithm that aims to derive the minimum score for a desired LEED level at minimal cost. Credits are studied and classified by their difficulty and the required cost, allowing for an algorithm that can suggest a customized approach to acquire the minimal required score. The practical, data-driven program developed herein helps shorten the consulting process and increases the accessibility of LEED certification.

Cloud data center’s total operating cost is conquered by electricity cost and carbon tax incurred due to energy consumption from the grid and its associated carbon emission. In this work, we consider geo-distributed sustainable datacenter’s with varying on-site green energy generation, electricity prices, carbon intensity and carbon tax. The objective function is devised to reduce the operating cost including electricity cost and carbon cost incurred on the power consumption of servers and cooling devices. We propose renewable-aware algorithms to schedule the workload to the data centers with an aim to maximize the green energy usage. Due to the uncertainty and time variant nature of renewable energy availability, an investigation is performed to identify the impact of carbon footprint, carbon tax and electricity cost in data center selection on total operating cost reduction. In addition, on-demand dynamic optimal frequency-based load distribution within the cluster nodes is performed to eliminate hot spots due to high processor utilization. The work suggests optimal virtual machine placement decision to maximize green energy usage with reduced operating cost and carbon emission.

The use of social media, such as social networking sites and instant messaging, in everyday life continues to spread, along with social media use in the workplace. This study examined how using social media like Facebook (social networking sites) and KakaoTalk (instant messaging) at work affects individual job performance. It also analyzed whether social media use has different effects on individual job performance depending on the characteristics of the given task. The results demonstrated that both Facebook and KakaoTalk had linearly positive effects on individual job performance. Moreover, task equivocality had a positive moderating effect on the relationship between KakaoTalk use and job performance. The results may have significant implications for firms reviewing their policies on employees’ social media use. Since using social media such as Facebook and KakaoTalk in the workplace improves job performance, firms may consider encouraging employees toward this practice. In particular, they may consider supporting those employees who perform tasks with high task equivocality in making use of instant messaging platforms.

AbstractThe defect evolution in graphene produced by ion beam bombardment is investigated by changing the ion species, irradiation energy and dose. Raman spectroscopy is performed to examine the defect yield produced under various ion beam bombardment conditions. The defect yields of the vacancy-type defect are well described by the linear energy transfer (L) and dose (d). By increasing Ld, the defect yields exhibit similar behaviours for all ion species. As a consequence, all the defect yields can be collapsed into a single curve by multiplying them by a single parameter, suggesting that the defect evolution under various ion beam bombardment conditions can be described in a simple formula.

Abstract Combustion control strategies to minimize the pollutants emission from municipal solid waste (MSW) incinerators are formulated based on the improved mixing of air with the products of incomplete combustion and the subsequent increase in oxidative destruction. Secondary air injection into the combustion chamber plays the key role in this mixing process. However, design variables of the air jet into the combustion gas stream are not clearly identified, and the performance of mixing and reaction is not fully understood. Three-dimensional flow simulation was performed to study the mixing performance of a full-scale incinerator combustion chamber according to the secondary air nozzle configuration. A detailed flow was analyzed and the degree of mixing was quantitatively evaluated by introducing a statistical parameter based on the chemical species distribution. The gas residence time distribution was analyzed using the particle trajectory. The overall flow field was strongly influenced by the nozzle c...

The number of mega data centers is steadily expanding as the cloud business expands. The data center consumes heavy electrical power because of their structural and equipment characteristics (e.g., workstations and cooling equipment). The mega data center becomes a microgrid (e.g., islanding operation). So, a lot of researchers have proposed the architecture design of a green energy data center to solve the heavy energy consumption problem and to reduce the emission release. For example, the goal of a green energy data center is to maximize energy efficiency while reducing environmental impacts (e.g., the reduction of greenhouse gases). So, the goal of this study is to design the most effective power system for a stand-alone hybrid green data center at the aspects of energy savings and the reliable operation. The ideal architecture of a stand-alone data center powered by renewable energy is initially designed by the HOMER program. Then, the steady-state and transient responses of a data center that functions as an island microgrid using DIgSILENT© Power Factory are examined.