Showing papers on "Efficient energy use published in 1999"
TL;DR: In this article, the authors extensively focused on energy and environmental impacts only, and discussed energy utilization and its major environmental impacts from the standpoint of sustainable development, including anticipated patterns of future energy use and subsequent environmental issues.
314 citations
TL;DR: In this paper, a comprehensive discussion of the future of energy use and the consequent environmental impacts in terms of acid precipitation, stratospheric ozone depletion and the greenhouse effect is presented.
313 citations
TL;DR: This work developed the design methodology for the low-power core-based real-time SOC based on dynamically variable voltage hardware and proposes a nonpreemptive scheduling heuristic, which results in solutions very close to optimal ones for many test cases.
Abstract: The growing class of portable systems, such as personal computing and communication devices, has resulted in a new set of system design requirements, mainly characterized by dominant importance of power minimization and design reuse. The energy efficiency of systems-on-a-chip (SOC) could be much improved if one were to vary the supply voltage dynamically at run time. We developed the design methodology for the low-power core-based real-time SOC based on dynamically variable voltage hardware. The key challenge is to develop effective scheduling techniques that treat voltage as a variable to be determined, in addition to the conventional task scheduling and allocation. Our synthesis technique also addresses the selection of the processor core and the determination of the instruction and data cache size and configuration so as to fully exploit dynamically variable voltage hardware, which results in significantly lower power consumption for a set of target applications than existing techniques. The highlight of the proposed approach is the nonpreemptive scheduling heuristic, which results in solutions very close to optimal ones for many test cases. The effectiveness of the approach is demonstrated on a variety of modern industrial strength multimedia and communication applications.
270 citations
TL;DR: In this article, the current status of EV energy sources and their suitability and potentiality are reviewed, and the concept of multiple energy sources for EVs is identified, hence the corresponding near term and long term measures are discussed.
218 citations
31 Oct 1999
TL;DR: In this paper, the authors proposed a stable, dynamic, distributed clustering for energy efficient networking, and evaluated the impacts of mobility and transmission power variation on network stability via simulation.
Abstract: This paper proposes a stable, dynamic, distributed clustering for energy efficient networking. Via simulation, we evaluate the impacts of mobility and transmission power variation on network stability.
195 citations
TL;DR: The paper discusses the various approaches in building integration of solar systems, and presents a number of successful examples, and some of the work being done on improving the design processes to account for the need for a holistic approach to solar building design.
177 citations
17 Aug 1999
TL;DR: This work presents the design of an energy efficient FPGA architecture by tackling both circuit design and architecture optimization issues concurrently and shows energy improvement of more than an order of magnitude when compared to existing commercial architectures.
Abstract: This work presents the design of an energy efficient FPGA architecture. Significant reduction in the energy consumption is achieved by tackling both circuit design and architecture optimization issues concurrently. A hybrid interconnect structure incorporating nearest neighbor connections, symmetric mesh architecture, and hierarchical connectivity is used. The energy of the interconnect is also reduced by employing low-swing circuit techniques. These techniques have been employed to design and fabricate an FPGA. Preliminary analysis show energy improvement of more than an order of magnitude when compared to existing commercial architectures.
153 citations
31 Oct 1999
TL;DR: It is shown that the incorporation of energy considerations into multicast algorithms can improve performance, and several algorithms for defining multicast trees when transceiver resources are limited are proposed.
Abstract: We address the problem of multicasting in military ad hoc networks from the viewpoint of energy efficiency. We discuss the impact of the wireless medium on the multicasting problem and the fundamental trade-offs that arise, and we propose and evaluate several algorithms for defining multicast trees when transceiver resources are limited. The algorithms select the relay nodes and their transmission power levels, and provide different degrees of scalability and performance. We show that the incorporation of energy considerations into multicast algorithms can improve performance.
147 citations
TL;DR: In this paper, a strategy for the energy-efficient design of the fully thermally coupled distillation column (Petlyuk system) is presented based on a dynamic model and uses two recycle streams as search variables.
145 citations
TL;DR: In this paper, the authors examine what lies behind this dichotomy in perspectives and conclude that although energy and technology markets certainly are not perfect (no markets are), the balance of evidence supports the view that there is not as much "free lunch" in energy efficiency as some would suggest.
Abstract: Enhanced energy efficiency occupies a central role in evaluating the efficacy and cost of climate change policies. Ultimately, total greenhouse gas (GHG) emissions are the product of population, economic activity per capita, energy use per unit of economic activity, and the carbon intensity of energy used. Although greenhouse gas emissions can be limited by reducing economic activity, this option obviously has little appeal even to rich countries, let alone poor ones. Much attention has therefore been placed on the role that technological improvements can play in reducing carbon emissions and in lowering the cost of those reductions. In addition, the influence of technological changes on the emission, concentration, and cost of reducing GHGs will tend to overwhelm other factors, especially in the longer term. Understanding the process of technological change is therefore of utmost importance. Nonetheless, the task of measuring, modeling, and ultimately influencing the path of technological development is fraught with complexity and uncertainty?as are the technologies themselves. Although there is little debate over the importance of energy efficiency in limiting GHG emissions, there is intense debate about its cost-effectiveness and about the government policies that should be pursued to enhance energy efficiency. At the risk of excessive simplification, we can characterize "technologists" as believing that there are plentiful opportunities for low-cost, or even "negative-cost" improvements in energy efficiency, and that realizing these opportunities will require active intervention in markets for energy-using equipment to help overcome barriers to the use of more efficient technologies. Most economists, on the other hand, acknowledge that there are "market barriers" to the penetration of various technologies that enhance energy efficiency, but that only some of these barriers represent real "market failures" that reduce economic efficiency. In this essay, we examine what lies behind this dichotomy in perspectives. Ultimately, the veracity of different perspectives is an empirical question and reliable empirical evidence on the issues identified above is surprisingly limited. We review the evidence that is available, finding that although energy and technology markets certainly are not perfect (no markets are), the balance of evidence supports the view that there is not as much "free lunch" in energy efficiency as some would suggest. On the other hand, a case can be made for the existence of certain inefficiencies in energy technology markets, thus raising the possibility of some inexpensive GHG control through energy-efficiency enhancement. We conclude with some reflections on the role of appropriate energy efficiency policy in climate change mitigation.
120 citations
17 Aug 1999
TL;DR: In this article, the authors leverage cycle-accurate energy consumption models to explore compiler and source code optimizations aimed at reducing energy consumption of battery-powered embedded systems, such as Smart-Badge.
Abstract: Energy-efficient design of battery-powered embedded systems demands optimizations in both hardware and software. In this work we leverage cycle-accurate energy consumption models to explore compiler and source code optimizations aimed at reducing energy consumption. In addition, we extend cycle-accurate architectural power simulation with battery models that provide battery lifetime estimates. The enhanced simulator and software optimizations are used to study and optimize the power dissipation of Smart-Badge, a wearable system based on the ARM microprocessor developed by HP Laboratories. We found that standard compiler optimizations give less than 1% energy savings. Source code optimizations are capable of up to 90% energy savings. In addition, our analysis of battery lifetime for the MPEG decoder implemented on the Smart-Badge shows that battery efficiency varies greatly with discharge currents on cycle-by-cycle basis and can cause up to 16% reduction in battery lifetime.
TL;DR: In this paper, an audit of 24 school buildings in Slovenia showed that the nominal heating power of boilers, and heat exchangers, which are used in district heating, showed a 57% overcapacity and the heat losses of the school buildings are 89% higher than the recommended values.
TL;DR: In this paper, a numerical multivariate optimization procedure is introduced, to draft the optimum building design variables at an early design stage, whereby the basic physical, technical and economic interactions between the building design options and energy flows are accounted for.
08 Apr 1999
TL;DR: The results indicate that the hierarchical generalized mesh structure shows the most promise in terms of energy efficiency, as it can optimize both local and global connections.
Abstract: In this paper we present and analyze a number of interconnect architectures for reconfigurable systems targeting applications in the areas of wireless communication and multimedia processing. Several interconnect architectures suitable for heterogeneous elements are proposed and then a methodology to evaluate the architectures is described. The results indicate that the hierarchical generalized mesh structure shows the most promise in terms of energy efficiency, as it can optimize both local and global connections.
TL;DR: The analysis here shows that protocols that aim to reduce the number of contentions perform better from an energy consumption perspective, although the receiver usage time, however, tends to be higher for protocols that require the mobile to sense the medium before attempting transmission.
Abstract: Energy efficiency is an important issue in mobile wireless networks since the battery life of mobile terminals is limited. Conservation of battery power has been addressed using many techniques such as variable speed CPUs, flash memory, disk spindowns, and so on. We believe that energy conservation should be an important factor in the design of networking protocols for mobile wireless networks. In particular, this paper addresses energy efficiency in medium access control (MAC) protocols for wireless networks. The paper develops a framework to study the energy consumption of a MAC protocol from the transceiver usage perspective. This framework is then applied to compare the performance of a set of protocols that includes IEEE 802.11, EC‐MAC, PRMA, MDR‐TDMA, and DQRUMA*. The performance metrics considered are transmitter and receiver usage times for packet transmission and reception. The time estimates are then combined with power ratings for a Proxim RangeLAN2 radio card to obtain an estimate of the energy consumed for MAC related activities. The analysis here shows that protocols that aim to reduce the number of contentions perform better from an energy consumption perspective. The receiver usage time, however, tends to be higher for protocols that require the mobile to sense the medium before attempting transmission. The paper also provides a set of principles that could be applied when designing access protocols for wireless networks.
TL;DR: This paper describes how energy efficiency in the wireless data link can be enhanced via adaptive frame length control in concert with adaptive error control based on hybrid FEC (forward error correction) and ARQ (automatic repeat request), and describes hardware and software implementations.
Abstract: Low power consumption is a key design metric for portable wireless network devices where battery energy is a limited resource. The resultant energy efficient design problem can be addressed at various levels of system design, and indeed much research has been done for hardware power optimization and power management within a wireless device. However, with the increasing trend towards thin client type wireless devices that rely more and more on network based services, a high fraction of power consumption is being accounted for by the transport of packet data over wireless links [28]. This offers an opportunity to optimize for low power in higher layer network protocols responsible for data communication among multiple wireless devices. Consider the data link protocols that transport bits across the wireless link. While traditionally designed around the conventional metrics of throughput and latency, a proper design offers many opportunities for optimizing the metric most relevant to battery operated devices: the amount of battery energy consumed per useful user level bit transmitted across the wireless link. This includes energy spent in the physical radio transmission process, as well as in computation such as signal processing and error coding. This paper describes how energy efficiency in the wireless data link can be enhanced via adaptive frame length control in concert with adaptive error control based on hybrid FEC (forward error correction) and ARQ (automatic repeat request). Key to this approach is a high degree of adaptivity. The length and error coding of the atomic data unit (frame) going over the air, and the retransmission protocol are (a) selected for each application stream (ATM virtual circuit or IP/RSVP flow) based on quality of service (QoS) requirements, and (b) continually adapted as a function of varying radio channel conditions due to fading and other impairments. We present analysis and simulation results on the battery energy efficiency achieved for user traffic of different QoS requirements, and describe hardware and software implementations.
TL;DR: In this article, the authors compared the energy efficiency of energy efficient motors with those of standard efficiency motors ranging from 5 to 300 HP, with reference to Bahrain's market, and discussed the energy-conservation capability of energy-efficient motors in the petrochemical industry.
TL;DR: The Center for Energy Efficient Buildings (CEE) as discussed by the authors is a program at the University of California at Berkeley that developed high-frequency solid-state ballasts for fluorescent lamps, low-emissivity and selective windows and the DOE-2 computer program for the energy analysis and design of buildings.
Abstract: ▪ Abstract After a first career as Professor of Physics, University of California at Berkeley, working in experimental particle physics at Lawrence Berkeley National Laboratory (LBNL), I was prompted by the 1973 Organization of Petroleum Exporting Countries (OPEC) oil embargo to switch to improving energy end-use efficiency, particularly in buildings. I cofounded and directed the Energy Efficient Buildings program at LBNL, which later became the Center for Building Science. At the Center we developed high-frequency solid-state ballasts for fluorescent lamps, low-emissivity and selective windows, and the DOE-2 computer program for the energy analysis and design of buildings. The ballasts in turn stimulated Philips lighting to produce compact fluorescent lamps. When they achieve their expected market share, energy savings from products started or developed at the Center for Building Sciences are projected to save American consumers $30 billion/year, net of the cost of the better buildings and products. In t...
TL;DR: In this paper, the authors examined manufacturing energy use in 13 OECD countries over the period 1971-1995 and compared the development in the periods after the oil price shocks of 1973 and 1979 with the period of relatively stable energy prices after the crash of 1986.
01 Jan 1999
TL;DR: A new noise-tolerant dynamic circuit technique is presented, and the average noise threshold energy (ANTE) and the energy normalized ANTE metrics are proposed for quantifying the noise immunity and energy efficiency of circuit techniques.
Abstract: Noise in deep submicron technology combined with the move towards dynamic circuit techniques for higher performance have raised concerns about reliability and energy efficiency of VLSI systems in the deep submicron era. To address this problem, a new noise-tolerant dynamic circuit technique is presented. In addition, the average noise threshold energy (ANTE) and the energy normalized ANTE metrics are proposed for quantifying the noise immunity and energy efficiency, respectively, of circuit techniques. Simulation results in 0.35 micron CMOS for NAND gate designs indicate that the proposed technique improves the ANTE and energy normalized ANTE by 2.54X and 2.25X over the conventional domino circuit. The improvement in energy normalized ANTE is 1.22X higher than the existing noise-tolerance techniques. A full adder design based on the proposed technique improves the ANTE and energy normalized ANTE by 3.7X and 1.95X over the conventional dynamic circuit. In comparison, the static circuit improves ANTE by 2.2X but degrades the energy normalized ANTE by 11%. In addition, the proposed technique has a smaller area overhead (69%) as compared to the static circuit whose area overhead is 98%.
TL;DR: In this article, the authors analyse which kinds of public planning, regulation and initiatives are suitable for the implementation of energy-conservation policies in Denmark, which is important elements of the Danish plans for implementing CO 2 -reduction targets.
Book•
15 Nov 1999
TL;DR: In this paper, it was shown that increased energy expenditure per neuron implies a decrease in average firing rate if energy efficient information transmission is to be maintained, and that coding schemes with the largest representational capacity are not, in general, optimal when energy expenditures are taken into account.
Abstract: In 1969 Barlow introduced the phrase “economy of impulses” to express the tendency for successive neural systems to use lower and lower levels of cell firings to produce equivalent encodings. From this viewpoint, the ultimate economy of impulses is a neural code of minimal redundancy. The hypothesis motivating our research is that energy expenditures, e.g., the metabolic cost of recovering from an action potential relative to the cost of inactivity, should also be factored into the economy of impulses. In fact, coding schemes with the largest representational capacity are not, in general, optimal when energy expenditures are taken into account. We show that for both binary and analog neurons, increased energy expenditure per neuron implies a decrease in average firing rate if energy efficient information transmission is to be maintained.
07 Dec 1999
TL;DR: This paper first formulates the minimum energy coding problem for RF transmission, then derives the energy optimal source coding algorithm from the source statistics, and combines this algorithm with Hamming codes for energy efficient error recovery to take a first step towards a novel energy saving wireless communication protocol.
Abstract: Source coding and channel coding algorithms minimizing the battery power needed for RF transmission are presented. Digital RF transmitters in portable devices using on/off keying modulation consume energy only when high bits are sent and virtually no energy is consumed when low bits are sent. Therefore, energy consumption can be minimized by devising codes that minimize the occurrence of high bits in transmitting information. In this paper, we first formulate the minimum energy coding problem for RF transmission. We then derive the energy optimal source coding algorithm from the source statistics. Finally, we combine this energy optimal source coding algorithm with Hamming codes for energy efficient error recovery. Overall, we take a first step towards a novel energy saving wireless communication protocol.
15 Sep 1999
TL;DR: A Finite Impulse Response filter architecture based on a Distributed Arithmetic approach with two supply voltages and variable bit precision operation is presented and it is demonstrated that 50% to 60% energy savings can easily be obtained in the case of speech data.
Abstract: A Finite Impulse Response (FIR) filter architecture based on a Distributed Arithmetic (DA) approach with two supply voltages and variable bit precision operation is presented. The filter is able to adapt itself to the minimum bit precision required by the incoming data and also operate at a lower voltage so that it still meets a fixed throughput constraint. As opposed to the worst case fixed precision design, our precision-on-demand implementation has an energy requirement that varies linearly with the average bit precision required by the input signal. We also demonstrate that 50% to 60% energy savings can easily be obtained in the case of speech data.
22 Aug 1999
TL;DR: In this article, a unified power flow approach to the modeling of hybrid electric vehicles (HEV) is proposed, resulting in a highly scalable and reconfigurable modeling tool, which is used in conjunction with a fuzzy logic, ruled-based controller to optimize the energy efficiency through the control of the power flows of a parallel HEV configuration.
Abstract: This paper proposes a unified power flow approach to the modeling of hybrid electric vehicles (HEV), resulting in a highly scalable and reconfigurable modeling tool. Furthermore, this simulation tool is used in conjunction with a fuzzy logic, ruled-based controller to optimize the energy efficiency through the control of the power flows of a parallel HEV configuration. Finally, this modeling and control approach is applied to the design and optimization of a hybrid electric sport-utility vehicle. The results show that this modeling approach provides the required modeling flexibility, and that the model and the control strategy based on this power flow approach can be optimized to yield significant fuel economy gains.
15 Feb 1999
TL;DR: A model is presented that can be used to determine an energy-efficient error correction scheme of a minimal system consisting of a general purpose processor and a wireless interface and it is shown that the required extra energy consumed by the wireless interface should be incorporated as well.
Abstract: Since high error rates are inevitable to the wireless environment, energy-efficient error-control is an important issue for mobile computing systems. We have studied the energy efficiency of two different error correction mechanisms and have measured the efficiency of an implementation in software. We show that it is not sufficient to concentrate on the energy efficiency of error control mechanisms only, but the required extra energy consumed by the wireless interface should be incorporated as well. A model is presented that can be used to determine an energy-efficient error correction scheme of a minimal system consisting of a general purpose processor and a wireless interface. As an example we have determined these error correction parameters on two systems with a WaveLAN interface.
01 Jul 1999
TL;DR: In this article, the authors presented an energy-design process for low-energy buildings and showed an actual project where energy costs were reduced by 63% by incorporating daylighting, passive solar heating and cooling and energy efficiency strategies into the building design.
Abstract: Designing and constructing low-energy buildings (buildings that consume 50% to 70% less energy than code-compliant buildings) require the design team to follow an energy-design process that considers how the building envelope and systems work together. A design team must set energy efficiency goals at the beginning of the pre-design phase. Detailed computer simulations are then used throughout the design and construction phases to ensure the building is optimized for energy efficiency and that changes to the design do not adversely affect the energy performance. Properly commissioning the building and educating the building operators are the final steps to successfully constructing a low-energy building. This paper defines this energy-design process and shows an actual project where energy costs were reduced by 63%. These energy savings were achieved by incorporating daylighting, passive solar heating and cooling, and energy efficiency strategies into the building design.
01 Jul 1999
TL;DR: In this paper, a study of projected near-term health benefits associated with greenhouse (GHG) reductions resulting from changes in energy efficiency and structure of energy use in the power and household sectors of China is presented.
Abstract: This is a study of projected near-term health benefits associated with greenhouse (GHG) reductions resulting from changes in energy efficiency and structure of energy use in the power and household sectors of China The work was commissioned by the former Office of Global and Integrated Environmental Health at WHO, in order to explore the scope for modelling in the assessment of such short-term health benefits China was selected as an appropiate case study for this work, as it fulfilled most of the criteria required, including the fact that it is a large country, with data sets available on air pollution and health, and with information on projected trends in the consumption of fossil fuels
Patent•
16 Apr 1999
TL;DR: In this paper, a human-powered or human-power assisted energy generation and transmission system adapted for use with vehicles is presented. But, the system is not suitable for the use of multiple sprockets.
Abstract: Efficient human-powered or human-power assisted energy generation and transmission system adapted for use with vehicles. The present invention can be utilized to achieve overall energy transmission efficiency superior to mechanical drives that utilize chains and sprockets or other mechanical drive mechanisms. The present invention can completely eliminate the need for multiple sprockets and the associated shifting mechanisms presently used in most bicycles. By utilizing high efficiency, light weight, direct-drive generators and motors, and an input controller, coupled with an efficient energy storage device, the present invention can reduce the overall weight and complexities of mechanical power transmissions, while, at the same time, offer higher overall efficiencies. In addition, the energy output to the output drive device can be controlled, through profiling and with an output controller, to maintain constant output, independent of instantaneous input. Thus, in a human-powered vehicle, constant thrust can be maintained significantly increasing the vehicle efficiency, compared to the cyclical thrust or torque generated using a mechanical system.
ENEA1
TL;DR: An integrated software tool environment is presented, and a methodology is proposed for the operational support of the local authority, for analysis of the impact of transport measures in terms of network energy consumption and pollutant emissions.
Abstract: An integrated software tool environment is presented, and a methodology is proposed for the operational support of the local authority, for analysis of the impact of transport measures in terms of network energy consumption and pollutant emissions. It is based on work done by the European Union within the save program (specific actions for vigorous energy efficiency)—Slam project (supporting local authorities methodology). As background, the Slam project is described, with the principal aspects and needs of environmental and traffic network management. The central section defines a methodology able to support technicians in recognizing the traffic asset and decision makers in evaluating interventions on urban transport infrastructures or technological systems. The role of the different models and their interactions with the transport telematics services currently active on the Florence (Italy) network is discussed. Finally, the procedure for calculating the traffic impacts on energy consumption is described with the help of a test case, the evaluation of a dedicated bus corridor in Florence.