Energy-efficient Mode Research Articles

Energy-Efficient Mode Switching Mechanism With Flexible Functional Splitting in Energy Harvesting Cloud Radio Access Networks

In energy harvesting cloud radio access networks, the sleep mode switching of small radio remote head (SRRH) and the functional splitting between SRRH and baseband unit are two important challenges for improving energy efficiency and throughput. In this paper, we propose an energy-efficient mode switching mechanism (E2MSM) with flexible functional splitting in which a controller determines the modes of SRRHs and functional splitting level by considering the renewable energy levels and populations of SRRHs. To optimize the performance of E2MSM, a constraint Markov decision process problem is formulated and a joint optimal policy on the sleep scheduling and the functional splitting level is obtained by a linear programming. Evaluation results demonstrate that E2MSM with the optimal policy can achieve comparable throughput to the throughput-oriented scheme while consuming no non-renewable energy.

Integration of OMNI channels and machine learning with smart technologies

Fast evolution of the Internet, mobile technologies and energy efficient communication protocols has given a new momentum to e-businesses and world become a global village. Due to increase in the usage of internet and number of mobile users, many companies use these channels to make their products and brands visible to their customers all over the world. Although, some progress has been made towards this direction but further exploration is required, particularly it is still a challenge to enhance in-flight passengers’ shopping experience through efficient and reliable communication protocols. In this paper, we proposed a framework for omni-channel which is based on cognitive radio and machine learning. The proposed cognitive radio communication protocols provide seamless connectivity to in-flight passengers through energy efficient mode like machine learning (ML). Here, machine learning helps to develop user profile, based on relevance feedback that address the problem of catalogue and information overload. In this paper, we also discuss various challenges and opportunities associated with the proposed omni-channel business model. Moreover, the role and impact of emerging technologies such as cognitive radio and 5G in realizing omni-channel businesses is discussed in this paper. Our results explain the seamless communication between aircraft users and merchandise, through reliable and efficient connectivity when the aircraft passes over different geographic areas i.e. urban/rural land or sea at different altitudes and geographic locations. Here, backup data channel is introduced which further enhance the reliability of connection especially when primary users turns ON during the communication. Furthermore, the proposed model helps to reduce communication time and consume less energy to transmit with high throughput as compared to the benchmark cognitive radio protocols.

Implementation of Stockholm´s First Pedestrian Plan ( breakout presentation )

Stockholm is a walking city. Around one third of all journeys are made on foot. The Urban Mobility Strategy places clear emphasis on prioritising space for high capacity, energy efficient modes with the least climate and environmental impact. However, investment in walking has been lacking, with cycling and public transport receiving dedicated investment spending. In 2016 the City Council approved Stockholm’s first pedestrian plan. The plan describes current conditions for walking, sets challenging targets for enhancing pedestrian friendliness and encouraging more people to walk, and has a clear and costed action plan for meeting these targets, prioritised in the City´s budget. Implementation is very much a work in progress. Cross-departmental working groups have been established to implement the plan. To date work has focussed on the following: Investments in pedestrian corridors; The pedestrian plan identifies strategic corridors that are or have the potential to become even more important in the future. "Walkshops" with representatives from a range of disciplines have been carried out in order to identify strengths and weaknesses and a package of improvement measures developed for the short and long term. Improvements focus on the pedestrian: more space to move freely alone or with company, pedestrian friendly lighting and junctions, seating to rest or take in the view, and waymarking as well as better maintenance. A recreational corridor has also been identified for improvements using a citizen led approach. "Living Stockholm" is the City's platform for testing innovative measures that promote use of the city on a human scale, involving local businesses and citizens as well as city planners. Car free streets during the summer and parks or outdoor seating instead of car parking contribute to a more vibrant city. The pedestrian plan is very much a testbed for maintaining and improving pedestrian friendliness in Stockholm. Key to its success is not only evaluating the outcome of the measures, but also the methods used to investigate and communicate the problem, as well as identifying potential conflicts. These areas are the focus of current work.

Linking energy and transport models to support policy making

Energy is an essential input to the transport system and transport energy use is a major component of the overall energy demand. Transport currently accounts for nearly half of global oil consumption and is the only field to be almost exclusively based upon a sole primary energy source. A possible evolution might be based on more oil-independent vehicles, on a higher use of energy efficient transport modes, on the integration of them through Intelligent Transport Systems (ITS). The answer to this partially global problem can be found both in transport and energy planning as well as in the adoption of new industrial and ICT technologies.Both energy strategy makers and transport planners need supporting tools for a better assessment of the impact of possible alternative policies and to set realistic targets for the transport sector.The present paper presents a conceptual link between two families of models - energy and transport - and provides some preliminary results of integrated modelling exercises for the Italian case, which show the importance of accurate ICT based data exchange between the models and the relevance of the comparison of present and future policy implementations.

Analysis of energy costs for catalytic ozone membrane filtration

Abstract Membrane fouling can be reduced through shear stress generated by cross-flow at the membrane surface. Previous work has shown that presence of ozone can reduce membrane fouling. In this work, the effect of ozonation and cross-flow on both membrane fouling on ceramic membranes and the energy cost for the process was studied. The effect of ozone dosage on membrane fouling was studied in both cross-flow and dead-end configurations. The performance of a manganese oxide coated membrane was compared with that of uncoated titanium oxide membrane. Membrane fouling decreased with increasing ozone dosages in the manganese oxide coated catalytic membrane, although increasing the dosage beyond 10–15 μg/s yielded limited improvement. The most energy-efficient mode of operation was found to be dead-end filtration using a manganese oxide coated membrane and a 10 μg/s ozone injection rate.

Energy-efficient operation modes of a frequency converter with a series-parallel resonant circuit under power stabilization at a variable load

An analysis of the power characteristics for a frequency converter is performed for matching with a varying load by means of a series-parallel resonant circuit. It is shown that a change in the active component of the load does not always lead to a proportional change in the input resistance of the resonance circuit, with at certain frequencies the resonant circuit even exhibiting a constant input resistance under a change in the load within a considerable range; that is, it has the properties of parametric output-power stabilization. At these frequencies, a large reactive component appears in the input impedance of the circuit, which does not allow one to obtain an operation mode close to a resonance one or achieve an acceptable energy-conversion efficiency. The frequency characteristics of the circuit have been studied under conditions of an extreme approach of its resonant frequencies. It is found that, in this case, owing to the distortions of the phase-frequency characteristic, one can obtain a quasi-resonant operation mode of the converter over the entire range of the load resistance. It is shown that the proposed method for the tuning of resonance circuit allows one, under a twofold change in the load, to achieve parametric stabilization of the output power with energy parameters of cosϕ > 0.94 at extreme points of the range of resistance variation. The obtained results are confirmed by simulation and physical experiment.

QoS Improved Energy Efficient Cooperative Relaying in Heterogeneous Networks Using Heterogeneous Relays

Cooperative communication is a crucial technology to sustain QoS of mobile user with increased energy efficiency. To improve QoS of cell edge users, energy efficiency and network utilization, cooperative communication can be used in heterogeneous networks. Source, destination and relays are multiple radio access nodes in heterogeneous networks hence source can communicate to relay and destination using one radio mode and relay can select some other efficient radio mode to retransmit message to destination. In this paper, QoS improved energy efficient radio mode and optimal relay(Q-EERR) selection algorithm with heterogeneous relays is proposed, in which each relay node considers dynamic variation of individual radio networks and efficiently select radio mode using Boltzmann–Gibb’s learning algorithm to retransmit message with required QoS and optimized energy. A novel heterogeneous relays introduced in proposed work act as store carry and forward relay (SCFR) for non real time services and decode and forward relay (DFR) for real time services. The proposed Q-EERR algorithm with heterogeneous relays is verified for real time services (voice and video conferencing), elastic service (FTP) and performances are compared with existing energy efficient relay and radio mode (EERR) selection algorithm with DFR and SCFR. It increases QoS of different services, network performance and reduces average transmit power compared with existing algorithm.

Investigation of peculiarities of decomposition of traction electric drives of mobile electrotechnical complexes

The object of this research is traction electric drive systems of mobile electrotechnical systems based on various types of motors. As a result of the system analysis of the object of research, it is established that it is possible to solve the problem of increasing the energy potential of an electromechanical system only in a complex manner. It is revealed that it is necessary to consider the established mode of operation of the entire system as a whole, taking into account the conditions for the rational operation of its individual components, provided that the interconnection between them is taken into account. It is shown that a practical situation is quite frequent where the rational operating mode of individual elements of an electromechanical system and optimal control of them does not lead to the operation of the entire system on the economic characteristics. This, as a consequence, increases the consumption level of diesel fuel. Conversely, the artificial compulsion of diesel operation on the economic characteristics leads to the operation of these electrical elements of the whole electromechanical system with significant power losses. To achieve the tasks of controlling the electromechanical system, the potential method is used. According to it, it is shown that the potential of not every individual element of the electric drive is important, but the potential of their aggregate in the interaction. With a successful combination of interaction and operating modes of each element and the whole structure in general, the total energy saving potential of the whole is greater than the sum of the energy saving potentials of individual elements of the electric drive. As a result, a synergy effect is obtained. It is also shown that the task of the control algorithm is to optimize the interaction of resources to obtain a positive synergy effect, the effect of reducing the level of losses in the system. As research result, a method of increasing energy efficiency for static and dynamic characteristics is proposed. The advantages of this method are the use of the synergetic properties of the system, the integrated provision of an energy-efficient operating mode. This leads to the achievement of the most rational specific level of fuel consumption and efficiency maximization of the electromechanical system.

Energy‐efficient power allocation and mode selection in hybrid multi‐cell architecture with limited backhaul capacity

This study addresses the problem of power allocation and mode selection in a hybrid coordinated multi-cell transmission system with limited backhaul capacity. The power consumption is considered as the extra expense due to data exchange via backhaul links. A novel hybrid multi-cell scheme is presented, in which each mobile station (MS) can dynamically select either interference channel or multi-cell multi-input and multi-output cooperation mode. To maximise energy efficiency (EE), the optimal power allocation scheme with low complexity is proposed. Moreover, the authors propose an energy-efficient mode selection metric for each MS, which reflects both benefits and extra expense brought by the selected cooperation mode. Based on the proposed metric, the optimal mode selection strategy maximising EE is obtained. Numerical results show that the hybrid multi-cell scheme outperforms the traditional single cooperation mode scheme in terms of EE.

Energy efficient process of nitrification and denitrification in activated sludge system with low organic load

The article summarizes the results of the second phase of a comprehensive study of energy efficient wastewater treatment processes in oxidation ditches. Dependence of the efficiency of simultaneous nitrification and denitrification at the change of oxygen regime have been determined at the second phase of the study. Results of the phase confirm the fundamental possibility of the withdrawal of biomass in energy-efficient mode with high quality of wastewater treatment.

Technical Diagnostics of Ventilation Units for Energy Efficiency and Safety of Operation

The article considers the questions of application of technical diagnostics fan installations methods for providing safe operation, the system of the technical maintenance improvement and repair. Due to the feet that one of the most important aspects in fan operation in mining is energy efficiency and energy saving, the lack of the data in the control of the level in vibration of stationary sensors is shown. The necessity of taking into account the geometric parameters of the intake channel has been shown, and also the necessity of creation of the reference masks for the assessment of technical condition and energy efficiency when operating fan installations in mining. The results of technical diagnostics of the main fans using the methods of vibration diagnostics are provided. Aspects of vibration at characteristic points are shown. The necessity for further accumulation of data characterizing vibration for adjustment of the reference masks and more accurate detection of defects and deviations from the energy-efficient mode of operation of the fan installations is given.

Alternating the twin rotor damper between two modes of operation to eliminate small vibrations

In previous research, the twin rotor damper (TRD), an active mass damper, was presented. In a preferred, energy-efficient mode of operation, the continuous rotation mode, two eccentric control masses rotate with constant angular velocities about two parallel axes in opposite directions. The resulting centrifugal forces combine into a directed harmonic control force that can be used for the control of structural vibrations. In another, more power-demanding mode of operation, the swinging mode, both control masses oscillate about certain angular positions. For both modes of operation, corresponding control algorithms have been developed. Furthermore, it has been found that the continuous rotation mode is not efficient for the damping of small vibrations, whereas the swinging mode can bring small vibrations to rest. In this paper, a control algorithm is presented, which uses the continuous rotation mode for large vibrations and the swinging mode for small vibrations. To validate the control algorithm, the TRD is numerically and experimentally applied on a single degree of freedom oscillator. The efficiency of the algorithm is studied for free vibrations.

Energy-Autonomous Wireless Communication for Millimeter-Scale Internet-of-Things Sensor Nodes

This paper presents an energy-autonomous wireless communication system for ultra-small Internet-of-Things (IoT) platforms. In the proposed system, all necessary components, including the battery, energy-harvesting solar cells, and the RF antenna, are fully integrated within a millimeter-scale form factor. Designing an energy-optimized wireless communication system for such a miniaturized platform is challenging because of unique system constraints imposed by the ultra-small system dimension. The proposed system targets orders of magnitude improvement in wireless communication energy efficiency through a comprehensive system-level analysis that jointly optimizes various system parameters, such as node dimension, modulation scheme, synchronization protocol, RF/analog/digital circuit specifications, carrier frequency, and a miniaturized 3-D antenna. We propose a new protocol and modulation schemes that are specifically designed for energy-scarce ultra-small IoT nodes. These new schemes exploit abundant signal processing resources on gateway devices to simplify design for energy-scarce ultra-small sensor nodes. The proposed dynamic link adaptation guarantees that the ultra-small IoT node always operates in the most energy efficient mode for a given operating scenario. The outcome is a truly energy-optimized wireless communication system to enable various classes of new applications, such as implanted smart-dust devices.

Food miles and food choices: the case of an upscale urban hotel in Hong Kong

ABSTRACTThe nature of food production and consumption has changed dramatically in recent decades. Food sources for hotels and resorts have been an increasingly important sustainability topic in recent years. Where food is sourced has important implications for the economic, environmental and socio-cultural sustainability of tourist destinations. Based on where food is sourced and the mode of transportation, food miles is calculated for an upscale urban hotel in Hong Kong over a 12-month period. Greenhouse gas emissions associated with these food miles are computed. Over three-quarters of the food and beverages procured travelled via sea, the most energy efficient mode of transportation. Follow-up interviews with the hotel's procurement and executive chefs reveal the motivation behind these purchase decisions. While quality of food is the main driver for chefs, the procurement department take quality and cost into consideration. These different motivations provide potential conflict in sourcing food sustainably. Another issue raised is that food being procured from nearby countries may have questionable health and safety standards. Just because food can be procured closer to the destination does not necessarily mean it is the most sustainable option.

Searching for the energy efficient operation modes of absorption refrigeration devices

The work demonstrates advantages of absorption refrigeration devices (ARD), as well as their essential shortcoming – a larger, in comparison to the compression analogs, energy consumption. In this connection, the main directions are examined of increasing energy efficiency of absorption refrigeration devices and the prospect of direction of improving the systems of automatic control is substantiated. It is shown that the only controlling influence on the efficiency of the ARD performance is achieved by the thermal power supplied in the generator-thermosyphon. Based on the analysis of the processes of heat mass exchange and the modes of flow of vapor-liquid water-ammonium mixture in the ARU generator–thermosyphon, the ambiguous influence of numerical values of the height of the lift part of the generator on energy characteristics of a standard ARU is shown. On one hand, this increase in height leads to the increase in hydraulic resistances at the motion of the VLM flow and heat losses, on the other hand, there appears a possibility of increasing the surface of heat mass exchange in the absorber. We run analysis of the effect of ambient temperatures on the ARD and ARU energy efficiency and the conditions of optimal operation. To examine the working modes of real objects, we carried out experimental studies of the modernized one-chamber ARD “Kiev-410” with a low-temperature compartment (LTC) of the Ash-160 type (manufactured by Vasilkovskiy Plant of Refrigerators, Ukraine) We obtained a set of quasi-static performance characteristics of the modernized one-chamber ARD “Kiev-410” with LTC of the Ash-160 type along the channels “thermal power supplied to the ARU generator – temperatures of the surface of the ARU elements in control points” at different conditions of heat removal from the external surface of dephlegmator (nominal, intensive heat removal, thermal insulation along the entire length of dephlegmator). As a result of conducted studies of the real object, we selected 5 types of the working modes of generator: optimal by energy efficiency (IІІ), “waiting” (ІІ), “accelerating” (IV) and two non-working modes (I and V). It was shown that at modes I and V the refrigeration cycle of ARU is not realized. Mode ІІ may be used by designers when working with positional algorithms of control as the “waiting” mode, which ensures the state of “readiness” for the rapid start; mode IV – as the “accelerating” at the start of ARU from non-operating state to the rapid attaining of the working load.

Energy Aware Persistence: Reducing the Energy Overheads of Persistent Memory

Next generation byte addressable nonvolatile memory (NVM) technologies like PCM are attractive for end-user devices as they offer memory scalability as well as fast persistent storage. In such environments, NVM’s limitations of slow writes and high write energy are magnified for applications that need atomic, consistent, isolated and durable (ACID) updates. This is because, for satisfying correctness (ACI), application state must be frequently flushed from all intermediate buffers, including processor cache, and to support durability (D) guarantees, that state must be logged. This increases NVM access and more importantly results in additional CPU instructions. This paper proposes Energy Aware Persistence (EAP). To develop EAP, we first show that the energy related overheads for maintaining durability are significant. We then propose energy-efficient durability principles that mitigate those costs, an example being flexible logging that switch between performance and energy-efficient modes and a memory management technique that trades capacity for energy. Finally, we propose relaxed durability (ACI-RD) mechanism used under critical low energy conditions that do not affect correctness. The initial results for several realistic applications and benchmark show up to 2x reduction in CPU and NVM energy usage relative to a traditional ACID-based persistence.

Investigation of heating of the drilling bits and definition of the energy efficient drilling modes

The work deals with the study of processes of heat exchange on a working face of a well when drilling with diamond drilling bits. The urgency of the problem stems from the development of new drilling technologies, where a flushing liquid is supplied in a pulse mode. The aim of the study is the justification of the settings of impulse flushing to enable energy-efficient resource-saving drilling mode. By such modes we understand those with the contact temperature not exceeding 600°C at the specified parameters of drilling. Experimental study and computer simulation of the processes of heating of drill bits with different modes of flushing were carried out. The task of joint impact of pulse flushing parameters (intervals and pauses) and mode parameters of drilling (flushing fluid consumption and downhole power) on the contact temperature on the working face was solved. On the basis of the obtained data, we designed a nomogram that allows determining the rational values of pause intervals and flushing fluid supply, level of downhole power, flushing fluid consumption, with which energy and resources efficient drilling mode is provided. Thus, the results of this work can be used to control the thermophysical processes on the working face and to select energy-efficient drilling modes.

Proposals for the formulation of law of control for articulated truck activated trailer hydrostatic transmission

The article is devoted to the development of scientifically based methods of creation of systems of automated adaptive control (SAAC) by “intelligent” transmissions multidrive-wheeled vehicles, such as articulated trucks with activated trailing links. The purpose of the studies is to formulate laws of control, the use of which in such SAAC should provide automatic selection in a variety of driving conditions of energy-efficient mode of power distribution between drive wheels. One of the most important issues in this case is to determine the parameters with necessary information content, which control of changes’ nature in the process of vehicle motion will allow SAAC to form control signals, ensuring keeping of the energy-optimal mode of motion in changing conditions. Obviously, these parameters should be the only ones that can be controlled during motion of articulated truck in real operation conditions by currently known and reliable methods. The article contains the results of this research obtained on the basis of the mathematical modeling of steady linear motion of articulated truck with activated trailing link, which wheels’ drive is provided by adjustable hydrostatic transmission in conditions of non-deformable bearing surface. The analysis was performed in the range of change gear ratios of trailer wheel drive when the transmission does not have interaxle power circulation. On the basis of studies the authors revealed the parameters that meet the above mentioned requirements, and also present the proposals for the formulation of control law for hydrostatic transmission of articulated truck activated trailer unit, which usage in the developed SAAC will improve energy efficiency of articulated trucks.

Mode Selection for Energy Efficient Content Delivery in Cellular Networks

Device-to-device (D2D) content delivery may improve resource efficiency for future content-centric cellular network due to the character of proximal transmission. However, when to use D2D technique can bring this performance improvement is still not clear. This letter investigates factors impacting on content delivery and proposes a criteria for delivery mode (cellular mode and D2D mode) selection. With this criteria, a more energy efficient delivery mode can be selected adaptively according to transmitter deployment, delivery coverage, channel quality, and quality-of-service (QoS) requirement. Simulation results show that compared with random mode selection scheme, the proposed mode selection strategy can reduce energy consumption for successful content delivery under different cases (e.g., up to 50% energy reduction for a successful content delivery). In addition, results on relationships among influencing factors and delivery efficiency match our theoretical analysis.

A quality-aware Energy-scalable Gaussian Smoothing Filter for image processing applications

Energy-efficient design is the prime requirement for modern portable devices as these devices employ compute intensive image/video processing cores which produces output for human consumption. The limited perception of human sense can be exploited to improve energy-efficacy via approximate designs. In this paper, a novel quality-aware Energy-Scalable Gaussian Smoothing Filter (ES-GSF) is proposed that significantly reduces energy requirement at the cost of slightly reduced quality. The energy scalability within ES-GSF is achieved by exploiting the relative significance of kernel coefficients existing on different boundaries. The ES-GSF computes significant boundaries for the given energy budget. Simulation results show that ES-GSF consumes 30.46% reduced energy with graceful quality degradation over the well-known existing architectures. Further, the ES-GSF can scale energy up to 65.05% when switched from high quality mode to energy-efficient mode. The efficacy of the proposed filter is demonstrated in edge detection where ES-GSF embedded edge detectors consume 29.9% less energy over the well-known existing architectures.