Area Budget Research Articles

Automated Linear and Nonlinear Reservoir Approaches for Estimating Annual Base Flow

Three automated base flow separation techniques based on linear and nonlinear reservoir approaches are used to identify the seasonal variation of base flow and to quantify the annual base flow for three subwatersheds of the Essex region in Southwestern Ontario, Canada. Significant differences in annual base flow estimated by linear and nonlinear reservoir algorithms are observed. In the nonlinear reservoir approach, the recession parameter is considered to be a seasonally variable parameter. The nonlinear reservoir approach fits streamflow recession better than the linear reservoir approach. The steeper slopes of seasonal flow duration curves in the 90% to 100% flow exceedance range show that the groundwater contribution to streamflow is relatively small in the study area. The precipitation-streamflow relationships show faster response of base flow during the period of high recharge. All of the methods show similar base flow estimation during the period of high evapotranspiration losses. The nonlinear reservoir approach represents the base flow response to precipitation better than the other methods. Therefore, the annual base flow estimated by the nonlinear reservoir approach is considered as the most reasonable estimation for the formulation of water budget of the study area. The method quantifies the occurrence of average annual baseflow as 34% of average annual streamflow.

Multi-Level Simulation Platform of Network-on-Chip forDesign Space Exploration

As multi-core architectures scale in size, on-chip networks (NoC) have become the main communication architecture, replacing dedicated interconnections and shared buses. NoC architectures have to deliver good latency-throughput performance in the face of very tight power and area budgets. Live power measurement is necessary for both hardware and software designer, but it requires too much time for simulation, especially for embedded systems. The major contribution of this paper is to present a simple method for rapidly estimating power consumption and find the hotspots in the network-on-chip(NoC) at two different resolutions. In addition to the low-level cycle-accurate simulation, we also build a high-level NoC simulation platform for multi-core SoCs, called TLM-PVT level. The platform, implemented by SystemC, allows early exploration of the performance and power consumption of NoC, which is able to handle arbitrary topologies and routing schemes. In the experiments, we compare the implemented high-level simulation platform with cycle-accurate simulator. The results show that the TLM-PVT simulator gives a high simulation speedup factor with a negligible performance estimation error margin.

Determination of the freshwater budget of tidal flats from measurements near a tidal inlet

The freshwater budget of a tidal flat area is evaluated from long-term hydrographic time series from an observation pole positioned in a tidal channel in the Hörnum Basin (Germany). For each tidal cycle, the freshwater budget is calculated from the total imported and exported water volumes and the corresponding mean densities. The variability of the budget on a tidal scale is characterised by a period of twice the tidal period, exhibiting a minimum when the tidal flats are dry around daylight hours during the foregoing low tide, and a maximum when low tide occurs at night; enhanced evaporation on the flats at daylight hours is identified as the driving process. On the average over one year, while winter observations are missing, the freshwater budget is negative for the years 2002–2005 and positive only for 2006. The interannual mean is negative and amounts to a freshwater loss of about 2 mm day −1, although the large-scale climate in this region is humid. The results demonstrate that the bulk parametrisations for the latent and sensible heat flux between the ocean and the atmosphere must not be applied for the tidelands.

Transconductance enhancement method for operational transconductance amplifiers

An improved recycling structure for an operational transconductance amplifier is proposed. The proposed structure separates the AC path from the DC path, and achieves a significant boost in transconductance under the same power and area budget. A folded-cascode amplifier employing the improved recycling structure was implemented in SMIC standard 0.13 μm CMOS process. Simulation results show that the enhancement of transconductance leads to 230% improvement in gain-bandwidth product and 13 dB boost in gain compared with the conventional folded cascode.

Reliable network-on-chip design for multi-core system-on-chip

Network-on-chip (NoC) architectures must deliver good latency-through put performance in the face of tight power and area budgets. However, in high-performance chip design, a significant design challenge is how to fulfill the requirements of circuit noise elimination, since the faults will slow down performance and dissipate much of the overall system power. This paper presents a simple coding scheme for reducing power dissipation, crosstalk noise, and crosstalk delay on the bus while simultaneously detecting errors at runtime. It uses a simple bus-invert encoding technique to reduce the prohibited transitions in terms of crosstalk noise and power dissipation. We also design a corresponding detector to detect errors at the input of the NoC routers. It can save energy by interrupting communications without storing and routing the packets when errors occur during transmissions. The experimental results for various multimedia applications show significant reduction in the number of patterns that are most likely to produce crosstalk errors. The results also show that it is attractive in terms of cost to apply the detecting logic to routers in the NoC with respect to the power consumption.

Tide and surge energy budgets for Eastern Canadian and Northeast US waters

A depth averaged barotropic model is used to quantify the effect of tides and storm surges on the energy budget for the coastal waters bordering the Northwest Atlantic. The model is first shown capable of producing realistic predictions of both tides and surges through comparison with independent sea level observations. In particular, it is shown that the model can predict tidal range with a typical RMS error of 20 cm, and realistic semi-diurnal to diurnal amplitude ratios. Storm surge hindcasts are also shown to be predicted with typical RMS errors less than 8 cm. Following successful validation of the model we produce, for the first time, spatial maps of maximum speed due to combined tide and surge (due to atmospheric forcing) current, tidal only current, and surge only current. The model is next used to examine the energy budget of the study area. It is shown that the energy flux vectors for the semi-diurnal and diurnal tides are very different. O 1 vectors tends to be more aligned with the bathymetry than the M 2 vectors. Most dissipation was found to occur in the high tide region of the Bay of Fundy. It is also shown that in the mean (i.e. over a season or a year), surges and tide–surge interaction do not play an important role in the energy budget. However, during a large surge event this is not true; surge and tide–surge interaction can have an order one impact on the energy balance. We discuss how such infrequent and unusually large events impact the nearshore environment.

Design-Space Exploration of Resource-Sharing Solutions for Custom Instruction Set Extensions

Customized processor performance generally increases as additional custom instructions are added. However, performance is not the only metric that modern systems must take into account; die area and energy efficiency are equally important. Resource sharing during synthesis of instruction set extensions (ISEs) can significantly reduce the die area and energy consumption of a customized processor. This may increase the number of custom instructions that can be synthesized with a given area budget. Resource sharing involves combining the graph representations of two or more ISEs which contain a similar subgraph. This coupling of multiple subgraphs, if performed naively, can increase the latency of the extension instructions considerably, and yet, as we show in this paper, an appropriate level of resource sharing provides a significantly simpler design with modest increases in average latency for ISEs. Our main contributions are the introduction of a parametric method for exploring the tradeoffs that can be achieved between instruction latency and implementation complexity, and the coupling of design-space exploration with fast area-delay models for the operators comprising each ISE. We present experimental evidence that our heuristic exposes a broad range of design points, allowing advantageous tradeoffs between die area and latency to be found and exploited.

A Low Power, Scalable, DAC Architecture for Liquid Crystal Display Drivers

The proliferation of portable electronic products such as cellular telephones and personal digital assistants has created a high demand for small format liquid crystal displays (LCD) with increasing bit resolution. The electronic drivers for these display applications must adhere to stringent power and area budgets. This paper describes a low-power, area efficient, scalable, digital-analog conversion (DAC) integrated circuit architecture optimized for driving small format LCDs. A 12 channel, 9-bit DAC driver based on this architecture, implemented in 0.5 mum CMOS technology and suitable for 1/4 VGA resolution displays, exhibited a 2 MSPS conversion rate, 252 muW power dissipation per channel using a 5 V supply, and a per DAC die area of 0.042 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This performance sets a new standard for DAC display drivers in joules per bit areal density at less than 0.58 pJ per bit per mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Prioritizing conservation targets in a rapidly urbanizing landscape

We used an optimization modeling framework to devise spatially explicit habitat acquisition and restoration strategies for 19 remnant-dependent butterflies in a rapidly urbanizing county in the Chicago area. We first identified the smallest sets of protected sites that would contain at least one population of each species, and two populations for species present in multiple sites. We then identified undeveloped properties contiguous with these sites whose acquisition would further enhance conditions for focal species. Next, we considered parcels in the surrounding landscape that could potentially be acquired and restored to provide additional habitat. Assuming that the conservation value of additional habitats would increase with their proximity to protected sites, we examined tradeoffs between distance to sites and the cost of acquisition and restoration. The tradeoff curves generated by the model represented choices among sets of reserves that varied widely with regard to cost and distance. Among the non-dominated solutions for a given total area budget, the best solutions depend on the decision makers preference for these two objectives. Sets along the frontier of these curves differed in total cost due to the variation in the number of wetlands per parcel, the number and cost of parcels that must be acquired to provide sufficient habitat, and restoration costs. Several parcels appeared in all solutions and should be prioritized for acquisition. Our general approach is readily adaptable to other locations and planning objectives, but the models would need to be modified to accommodate different target species and their habitat requirements.

Designing nature reserves in the face of uncertainty

AbstractConservation reserves are one of the most important tools for managing biodiversity. Ever since Diamond, based on theory of island biogeography, proposed that a single large reserve was preferable to several small reserves of the same total area, there has been an enduring debate about the veracity of his assertion. The so-called SLOSS debate - should we have a Single Large reserve Or Several Small reserves - features in every conservation text book and is central to conservation theory. Population dynamic models suggest that the design that minimizes the risk of extinction of species is case-specific, with the optimal number of reserves ranging between one and very many. Uncertainty is pervasive in ecology, but, the previous analyses of the SLOSS debate have not considered how uncertainty in the model of extinction risk might influence the optimal design. Here we show that when uncertainty is considered, the SLOSS problem is simplified and driven more by the aspirations of the manager than the population dynamics of the species. For a given budget of land area to be reserved in a region, the optimal solution is to have on the order of twenty or fewer reserves for any species. This result shows counter-intuitively that considering uncertainty actually simplifies rather than complicates decisions about designing nature reserves.

Bog Iron Ores and their Potential Role in Arsenic Dynamics: An Overview and a “Paleo Example”

AbstractBog iron ores (BIOs), i.e. terrestrial accumulations of iron (Fe) minerals forming within the zone of groundwater oscillation, have been described in several regions in Germany and other countries. Since BIOs are composed of a variety of Fe minerals, primarily amorphous Fe hydroxides, they are likely to have an influence on the arsenic (As) dynamics of an area, as these minerals represent important natural As sources and sinks. In this study, mineralogical research results (XRD, microscopy) of altered BIOs of Tertiary age (“paleo” BIOs or PBIOs), occurring within Cretaceous sands in an area of North Rhine‐Westphalia, are briefly presented. Genesis and mineralogical evolution of the categorized five different types of PBIOs, along with hydrogeochemical data from the literature, are discussed and compared to studies describing Holocene BIOs from other areas. In doing so, striking similarities (depositional environment, substratum, Fe source and its transport, geochemical evolution, and mineralogy) became evident. Differences in mineralogical and chemical composition can be attributed to the longer period of oxidation that the PBIOs have undergone (Fe hydroxide “aging”). This process is still ongoing (most of the groundwaters in the area plot in the goethite stability field) and leads to a higher stability of the Fe phases and thus, a stronger As retention. The known impact of the PBIOs on the As budget of the study area (they represent the source for elevated As concentrations in soils) can be transferred to more recent environments fostering BIO formation. These are likely to be even more important As sinks – and sources – as they contain higher Fe concentrations, higher shares of potentially mobile As and highly variable redox conditions which might lead to an As output from the BIOs into groundwater, soils and plants. Therefore, BIOs and their potential role in As behaviour are not only of scientific, but also of public interest.

Self-Adaptive Data Caches for Soft-Error Reliability

Soft-error induced reliability problems have become a major challenge in designing new generation microprocessors. Due to the on-chip caches' dominant share in die area and transistor budget, protecting them against soft errors is of paramount importance. Recent research has focused on the design of cost-effective reliable data caches in terms of performance, energy, and area overheads, based on the assumption of fixed error rates. However, for systems in operating environments that vary with time or location, those schemes will be either insufficient or overdesigned for the changing error rates. In this paper, we explore the design of a self-adaptive reliable data cache that dynamically adapts its employed reliability schemes to the changing operating environments thus to maintain a target reliability. The proposed data cache is implemented with three levels of error protection schemes, a monitoring mechanism, and a control component that decides whether to upgrade, downgrade, or keep the current protection level based on the feedback from the monitor. Our experimental evaluation using a set of SPEC CPU2000 benchmarks shows that our self-adaptive data cache achieves similar reliability to a cache protected by the most reliable scheme, while simultaneously minimizing the performance and power overheads.

A biophysical process model of tree mortality in surface fires

The mechanisms governing tree mortality in surface fires are poorly understood, owing in large part to the absence of a process-based framework for defining and evaluating these mechanisms. This paper begins the development of such a framework by deriving a first-order process model of tree mortality in surface fires (intensities less than approximately 2500 kW·m–1). A buoyant line-source plume model is used to drive heat transfer models of vascular cambium and vegetative bud necroses, which are linked to tree mortality using an allometrically-based sapwood area budget. Model predictions are illustrated for white spruce ( Picea glauca ), lodgepole pine ( Pinus contorta ), and trembling aspen ( Populus tremuloides ) and are compared with independent mortality data for Engelmann spruce ( Picea engelmannii Parry ex Engelm.) and Pinus contorta Dougl. Results help define first-order mortality mechanisms and suggest second-order mortality mechanisms that should be incorporated into future modeling efforts.

Organising a cookery session

Choosing the right equipment to suit the needs of your pre-school or nursery is not always easy. You will have to consider the room available for a cooking area and your budget. You may already have some utensils or even a cooker but if you are starting up a cooking area, especially on limited funds, choosing the right equipment is important.

Low-power low-area network-on-chip architecture using adaptive electronic link buffers

In the deep sub-micron regime, the performance of network-on-chip (NoC) architectures is bound by the limited power and area budget. Proposed is a low-power low-area NoC architecture using a novel power-efficient control circuit that enables repeaters along the inter-router links to function as adaptive link buffers, thereby reducing the number of buffers required in the router. Simulation results in the 90 nm technology show power savings of nearly 45% and area savings of 50% for the proposed technique.

Adaptive routing strategies for fault-tolerant on-chip networks in dynamically reconfigurable systems

An investigation into an effective and low-complexity adaptive routing strategy based on stochastic principles for an asynchronous network-on-chip platform that includes dynamically reconfigurable computing nodes is presented. The approach is compared with classic deterministic routing and it is shown to have good properties in terms of throughput and excellent fault-tolerance capabilities. The challenge of how to deliver reliability is one of the problems that multiprocessor system architects and manufactures will face as feature sizes and voltage supplies shrink and deep-submicron effects reduce the ability to carry out deterministic computing. It is likely that a new type of deep-submicron complex multicore systems will emerge which will be required to deliver high performance within strict energy and area budgets and operate over unreliable silicon. Within this context, the paper studies an on-chip communication infrastructure suitable for these systems.

Generating sustainable towns from Chinese villages: A system modeling approach

The great majority of China's developing towns will be extensions of already existing villages. With the prospect of hundreds of millions of Chinese farmers projected to leave their villages to become industrial workers in new and expanded towns within the next few years, new challenges will be faced. As expansion and modernization progress, this development moves from the traditional village model that operates not far from resource sustainability to increasingly unsustainable patterns of commerce, urban development, and modern life. With such an unprecedented mass migration and transformation, how can Chinese culture survive? What is to become of the existing million plus agricultural villages? How can these massively unsustainable new industrial towns survive? In the European Commission sponsored research program SUCCESS, researchers worked from the scale of the Chinese village to find viable answers to these questions. To address these issues, the Center for Sustainable Cities, one of the SUCCESS teams, studied the metabolism of several small villages. In these studies, system dynamics models of a village's metabolism were created and then modified so that inherently unsustainable means were eliminated from the model (fossil fuels, harmful agricultural chemicals, etc.) and replaced by sustainability-oriented means. Small Chinese farming villages are unlikely to survive in anything like their present form or scale, not least because they are too small to provide the range of life opportunities to which the young generation of educated Chinese aspires. As a response to this realization as well as to the many other threats to the Chinese village and its rural way of life, it was proposed that one viable path into the future would be to enlarge the villages to become full service towns with sufficient diversity of opportunity to be able to attract and keep many of the best and brightest young people who are now migrating to the larger cities. Starting with the village in its sustainability-oriented model form, the village model would be enlarged both quantitatively and qualitatively through many trial iterations. A research program is described whereby an operational definition of the sustainable city is developed as a means of creating these enlarged models through citizen participation assisted by outside experts using software under development called the Sustainability Engine™ to guide the process and provide feedback as to the consequences of various proposals that are brought to the table. As this process is continued, the village would be incrementally enlarged and made more diverse and more complex through a variety of scenarios until it would emerge as a modern, sustainable town or city. In this way, through a participatory, balance-seeking civil society process involving villagers and scientists in what the Center for Sustainable Cities calls the Sustainable City Game, the villages can become the DNA for generating future sustainable Chinese towns and cities. As an extension of this discussion, a new urban model, the Sustainable City-as-a-Hill, is presented that responds to both the qualities of the traditional Chinese village as well as to the modern demands of industrial and post-industrial economies and, in particular, to the need for sustainable urban patterns. In addition a new concept, the Sustainable Area Budget (SAB) is introduced which definitively creates the boundary condition for both modeling the sustainable city and presenting the quest for the sustainable city-region as a coherent, scientific design process.

Optimizing a piezometric network in the estimation of the groundwater budget: a case study from a crystalline-rock watershed in southern India

An estimate of the groundwater budget at the catchment scale is extremely important for the sustainable management of available water resources. Water resources are generally subjected to over-exploitation for agricultural and domestic purposes in agrarian economies like India. The double water-table fluctuation method is a reliable method for calculating the water budget in semi-arid crystalline rock areas. Extensive measurements of water levels from a dense network before and after the monsoon rainfall were made in a 53 km2 watershed in southern India and various components of the water balance were then calculated. Later, water level data underwent geostatistical analyses to determine the priority and/or redundancy of each measurement point using a cross-validation method. An optimal network evolved from these analyses. The network was then used in re-calculation of the water-balance components. It was established that such an optimized network provides far fewer measurement points without considerably changing the conclusions regarding groundwater budget. This exercise is helpful in reducing the time and expenditure involved in exhaustive piezometric surveys and also in determining the water budget for large watersheds (watersheds greater than 50 km2).

Indirect determination of the heat budget of tidal flats

A method is presented to calculate indirectly the heat budget of a tidal flat area from downstream observations of temperature and horizontal velocity in a tidal channel. It is only necessary to establish a relationship between the velocity and the volume flux. Then the heat budget of the upstream region is determined by integrating the heat flux over one tide. The proposed method is applied to long-term measurements obtained in 2004 at two sites in a tidal channel in the Hörnum Basin, German Wadden Sea. At the site located farther downstream in the channel, the upstream catchment area is diagnosed to export heat (heat gain in the interior) from March to August, while import is diagnosed for the same period of time at the other upstream site. From September to November the situation is reversed. An analytical estimate suggests that the sign of the budget is controlled by the tidal prism and the length of the dry-falling period of the flats in the respective upstream region. In addition, a simple model is developed which can be used to determine the integral bottom heat flux of the tidal flats.

Parallel Programmable Ethernet Controllers: Performance and Security

Programmable network interfaces can provide network servers with a flexible interface to high-bandwidth Ethernet links, but they face critical software and architectural challenges. This article explores architectural and software support for an efficient programmable 10 Gigabit Ethernet controller. The design is then extended to support a self-securing Gigabit Ethernet controller that performs intrusion detection on all network data frames. Both raw performance and security require high- bitrate frame data transfer, low-latency metadata access, and intensive computational capacity while still operating under the area, cost, and power budget of a peripheral device. These goals are achieved using a combination of parallel lightweight processing cores, an explicitly-partitioned memory system, and dedicated hardware assists. The firmware on the network interface is designed to utilize these resources efficiently by exploiting frame-level, flow-level, and task-level concurrency.