Machine learning using magnetic stochastic synapses

Nonvolatile data storage in today's computers is based on magnetic materials. Hard disk drives (HDD) feature ferromagnetic thin films for recording bits as regions with different magnetizations in the film. At present, the efforts of decreasing HDD size while increasing storage capacity, however, face fundamental limits, namely, the so-called superparamagnetic effect. Research into new generations of magnetic data-storage devices, amongst others, considers as its basic working principle current-induced magnetic domain-wall motion (CIDWM) in magnetic nanowires. In this paper, we present simulation studies of external magnetic field-induced magnetization reversal and domain-wall motion in nanowires of various sizes and shapes. Our results contribute to the basic design principles applied to magnetic structures used in CIDWM experiments. Parameters, such as wire thickness and wire-pad geometries are investigated, and important threshold magnetic field values are presented. In addition, we introduce a novel method of domain-wall trapping in a magnetic wire using the fringe fields of close-by magnets.

Energy retrofitting the existing building stock is crucial to reduce thermal discomfort, energy consumption, and carbon emissions. However, insulating and enhancing the thermal mass of an existing building wall using traditional methods is a very challenging and expensive task. There is a need to develop a material that can be applied easily in an existing occupied building without much interruption to occupants’ daily life while also having high thermal resistance and heat storage capacity. This study aimed to investigate a potential building wall retrofit strategy combining aerogel render and Phase change materials (PCM) because aerogel render is highly resistive to heat and PCM has high thermal mass. While a number of studies investigated the thermal and energy-saving performances of aerogel render and PCM separately, no study has been done on the thermal and energy-saving performance of the combination of PCM and aerogel render. In this study, the performance of 12 different retrofit strategies, including aerogel and PCM, were evaluated numerically in terms of heat stress, energy savings, peak cooling, emission, and lifecycle cost using a typical single-story Australian house. The results showed that applying aerogel render and PCM on the outer side of the external walls and PCM and insulation in ceilings is the best option considering all performance indicators and ease of application. Compared to the baseline, this strategy reduced severe discomfort hours by 82% in a free-running building. In an air-conditioned building, it also decreased energy use, peak cooling demand, CO2 emission, and operational energy cost by 40%, 65%, 64%, and 35%, respectively. Although the lifecycle cost savings for this strategy were lower than the “insulated ceiling and rendered wall without PCM” case, the former one was considered the best option for its superior energy, emission, and comfort performance. Parametric analysis showed that 0.025 m is the optimum thickness for both PCM and aerogel render, and the 25 °C melting point PCM was optimum to achieve the best results amongst all performance indicators for a typical Australian house in Melbourne climate.

Designing waterfront redevelopment generally focuses on attractiveness, leisure, and beauty, resulting in various types of building and block shapes with limited considerations on environmental aspects. However, increasing climate change impacts necessitate these buildings to be sustainable, resilient, and zero CO2 emissions. By producing five scenarios (plus existing buildings) with constant floor areas, we investigated how buildings and district forms with building integrated photovoltaics (BIPV) affect energy consumption and production, self-sufficiency, CO2 emission, and energy costs in the context of waterfront redevelopment in Tokyo. From estimated hourly electricity demands of the buildings, techno-economic analyses were conducted for rooftop PV systems for 2018 and 2030 with declining costs of rooftop PV systems. We found that environmental building designs with rooftop PV system are increasingly economical in Tokyo with CO2 emission reduction of 2–9% that depends on rooftop sizes. Payback periods drop from 14 years in 2018 to 6 years in 2030. Toward net-zero CO2 emissions by 2050, immediate actions are necessary to install rooftop PVs on existing and new buildings with energy efficiency improvements by construction industry and building owners. To facilitate such actions, national and local governments need to adopt appropriate policies.

Logistics activity is both a major energy consumption user and an important CO₂ emission source. As logistics service activity rises in the city, it is crucial to improve the efficiency of fuel usage, as well as decrease the CO₂ emission of unit shipment using vehicle routing optimization. Based on the analysis of the characteristics of energy consumption and emission factors of CO₂ in the vehicle routing problem with multiple vehicles, this paper investigates the problem of fleet size and mixed vehicle routing problem considering CO₂ emissions cost (Green Fleet Size and Mixed Vehicle Routing Problem, G-FSMVRP ). A heuristic algorithm based on a genetic algorithm is given. Finally, a numerical simulation example is given to illustrate the optimization model and its algorithm. The findings show that: (1) the shortest route does not necessarily produce the least energy consumption; (2) compared with the traditional vehicle routing (based on shortest path), vehicle routing considering CO₂ emissions has a lower total cost, but longer distance travelled; and, (3) the genetic algorithm is an effective algorithm to solve the green vehicle routing problem.

Cost of energy and environmental policy in Portuguese CO2 abatement—scenario analysis to 2020

Energy-saving has become one of the basic strategies for developing countries like Turkey that need energy imports. One of these strategies is energy-efficient building designs. The energy-efficient building envelope, which is one of the most important components of energy-efficient building designs, is of great importance in terms of insulation, indoor comfort, and environmental effects. In addition, the climatic and seismic characteristics of the regions where the buildings will be built are a matter of curiosity for building designers. It is an important problem to determine the effect of climate and earthquake zones on the building envelope. In this study, the effects of climate and earthquake zones on the costs of the building life cycle, together with the building envelope properties, are investigated. Life-cycle cost assessment (LCA) analysis is applied by considering the parameters of building envelope material cost, heating energy consumption cost, cooling energy consumption cost, CO2 emission cost, embodied carbon cost, and earthquake-based repair cost. A total of fourteen different decision variables are taken into account, including exterior plaster, wall, and roof insulation material, wall, interior plaster, the thickness of these materials, window type, and window/wall ratio. Significance levels of decision variables for heating energy consumption, cooling energy consumption, and CO2 emission are calculated. It is determined that five decision variables for heating energy consumption, four for cooling energy consumption, and seven for CO2 emission are more important. It is an interesting pattern that earthquake zones have 28, 46, and 13% importance for heating energy consumption, cooling energy consumption, and CO2 emission. It has been observed that the EnergyPlus based ANN approach proposed for LCA analysis provides over 95% accuracy on the sample data set.

This chapter contains a brief survey of the remarkable magnetic properties of low-dimensional magnetic objects such as nanodisks , nanorings , nanotubes , and nanowires . These nanoscale systems have been intensely studied in the last years, not only because of these properties, but also for their enormous potential for high-density information storage and other applications. Nanodisks and nanorings are promising as elements of bit-patterned magnetic recording systems, nanotubes and nanowires , among other applications, can store and process information through the motion of magnetic domain walls

The aim of this study was to evaluate the energy usage and total operation cost of the tractor grabber. The data was collected at FELCRA BERHAD Kawasan Titi Gantong, Bota, Perak. The total cost included all the operation in loading system and evacuation process of fresh fruit bunch (FFB). This study evaluated the energy usage of tractor grabber for three consecutive months using a newly purchased Mini Tractor Grabber Kubota L4400. This study was conducted based on the energy input-output methodology. Mathematical equations are used to determine the field capacity and examine energy usage. The result found that 153.38 MJha⁻¹ of input energy was required to produce 328.43 metric ton per month of FFB in June. The energy was dominated by fuel consumption, machinery and followed by labour. The total operating cost is based on the field capacity of the machine. This study was conducted and obtained the result, assumed that the total cost for a year is RM 47,444.24 and the cost per metric ton is RM 9.76 with energy consumption of 174.23 MJ. Conclusively, it means that the energy usage and cost of operation is efficiently and effectively used in oil palm productivity in FELCRA BERHAD Kawasan Titi Gantong.

Integration of energy aspects into the economic lot scheduling problem

As the demand for electricity increases day by day, the integration of battery energy storage systems (BESS) has become highly influential when considering power systems. Battery energy storage systems have the advantage of improving the economy of power with environmental benefits. For the successful integration of battery energy storage systems, the optimal placement and economic dispatching of energy is required to avoid problems. A BESS will provide power whenever the DGs are unable to provide power to the system. In the case of solar power, the sun cannot provide light to solar panels all day and wind turbines encounter variations in wind supply. This research proposes optimal placement within a BESS and a reduction in the cost of energy usage from conventional sources by considering BESSs with active power capability via an IEEE-33 bus system using an algorithm called mixed-integer second-order cone programming (MI-SOCP), modeled in MATLAB using MOSEK solver to reduce the cost of energy as an objective function. The MI aspect of the algorithm is used to find out the optimal placement of the BESS and the SOCP part is used to reformulate the economic dispatch problem in an AC-distributed BESS.

The paper's goal is to unify practical and theoretical aspects of internalisation of external costs, in line with the “polluter pays” and “user pays” principles. Due to the impossibility of applying an ideal economic solution for internalisation of external costs, alternative solutions have to be developed and implemented. One of the possible solutions for internalisation of external costs of CO2 and pollutant emissions from passenger cars is presented in this paper. It is a new methodology for calculating annual circulation taxes on passenger cars. This methodology, besides CO2, also takes into account the pollutants whose emissions are regulated by the Euro standards (CO, HC, NOx and PM), as well as the vehicle age and kilometres driven. The proposed methodology has been tested on some of the best-selling passenger cars in Europe. The results of analysis show significant differences between our methodology and the methodologies that are used in five European countries (Ireland, the United Kingdom, Malta, Luxembourg and Sweden), which use the CO2 emissions as a reference value for their calculation. Also, we have proved that the annual circulation tax, calculated using our methodology, provide better internalisation of external costs compared to the fuel tax.

The ebullated bed residual oil hydrocracking is a well-established technology wherein the vacuum residue (VR) of crude oil is converted into light valuable oils. This research work targeted to optimize the hydrocracking process by integrating the pump-free ebullated bed reactor (PF-EBR) with a membrane-based gas synthetic recovery system. A PF-EBR hydrocracking unit with a feed capacity of 3 × 106 t/a (ton per annum) of vacuum residues was modeled by the axial dispersion model; the 5-lump axial dispersion model and the finite difference model for PF-EBR and membrane unit were developed and packaged as self-defined extensions in Aspen HYSYS, allowing the integrated process to be evaluated in high efficiency and accuracy; the proposed model was further validated by the experimental data of the pilot and 5 × 104 t/a industrial unit. The results of process optimizations showed that the membrane-aided separation system demonstrated better performance than the conventional condensation system in separating hydrogen and hydrocarbons from bulk refinery gas. The recovery of hydrogen from the reactor effluent resulted in 30.0% drop in reactor fresh makeup hydrogen cost; the membrane-based system separated the light hydrocarbons from refinery flash gases, which boosted the net profit of hydrocarbon recovery by 80%, leading to $122.3 × 106/a increase in the total product sale (about 7% of the hydrocracker total sale). This study bridged the gap between theoretical models and industrial PF-EBR processes and provided a designing framework for the integrate process of PF-EBR VR hydrocracking and gas synthetic recovery system. The described improvements implied significant reductions in energy cost, carbon footprint, and operational cost; the estimated reduction in CO2 emissions is around 2.6 × 104 t/a; all are attributed to the thorough gas recovery.

Unsupervised learning requiring only raw data is not only a fundamental function of the cerebral cortex, but also a foundation for a next generation of artificial neural networks. However, a unified theoretical framework to treat sensory inputs, synapses, and neural activity together is still lacking. The computational obstacle originates from the discrete nature of synapses, and complex interactions among these three essential elements of learning. Here, we propose a variational mean-field theory in which the distribution of synaptic weights is considered. The unsupervised learning can then be decomposed into two intertwined steps: A maximization step is carried out as a gradient ascent of the lower bound on the data log-likelihood, in which the synaptic weight distribution is determined by updating variational parameters, and an expectation step is carried out as a message passing procedure on an equivalent or dual neural network whose parameter is specified by the variational parameters of the weight distribution. Therefore, our framework provides insights on how data (or sensory inputs), synapses, and neural activities interact with each other to achieve the goal of extracting statistical regularities in sensory inputs. This variational framework is verified in restricted Boltzmann machines with planted synaptic weights and handwritten-digits learning.

Optimal energy management of a grid-connected dual-tracking photovoltaic system with battery storage: Case of a microbrewery under demand response

The use of differing materials for distribution and transmission pipelines with equivalent outside diameters within water and waste water systems is many times deemed by the owners as an “apples to apples” comparison when evaluating the initial construction cost. The scope of this paper will focus upon the significant energy costs that are saved (or expended) over the life of the system as a result of the decisions made during the design and specifications stage of a project in determination of the pipeline material to be utilized. It will be shown that use of pipeline materials with larger inside diameters can save a utility virtually millions of dollars in energy costs over the life cycle of the pipe. Serving as a former lead executive for the nation’s largest investor owned water utility, I am intimately aware of the scrutiny of customers when it comes to supporting escalating operating costs of a utility. Construction projects are easier to identify and substantiate. This paper will find through use of Present Worth Analysis that utilities are considering, or in many cases disregarding, the sustainability of energy operating costs within their utility by taking into account (or not) the inside diameter of pipeline materials utilized within their system. The decision by utility system owners to utilize the least expensive pipeline materials in construction projects may overtime create very significant energy operating costs which can ultimately affect the sustainability components of the system. These escalating costs when not identified at the outset of project design will assimilate the Boiled Frog Theory, incrementally rising each year unnoticed until potentially millions of dollars are being expended in energy costs over the years as a result of smaller inside diameter