Aggregate Utility Research Articles

Interference-aware User Association under Cell Sleeping for Heterogeneous Cloud Cellular Networks

In this letter, we investigate an interference-aware user association scheme with cell sleeping technique in heterogeneous cloud cellular networks where the operation state of each base station (BS) is controlled by a cloud computing center. A user association problem which maximizes the user aggregate utility is formulated. Due to high computational complexity of the traversal method, we propose a distributed heuristic algorithm to get the suboptimal solution. At each cycle, the user selects the best BS by imposing a price which is proportional to the interference the BS provides. The BSs without any associated user will be switched off. Based on the varying network topologies, different combinations of active and switch-off BSs can also be obtained during different cycles. Numerical simulation results indicate that the proposed scheme can achieve remarkable throughput gains under the same power consumption, especially in large scale networks.

Study on the Utilization of Innovative Air-cooled Slag Aggregates in Precast Concrete

Study on the Utilization of Innovative Air-cooled Slag Aggregates in Precast Concrete

Compressive Strength Evaluation of Mortars Containing ISF Slag and Marble Powder

Increase in utilization of conventional aggregates by the construction sector has led to the depletion of natural resources, raising concerns with regard to their conservation. To address these issues, attempts have been made to utilize industrial wastes as fine aggregate in construction materials. In the present study industrial waste such as ISF slag and marble dust have been used in cement sand mortars of ratio 1:3, 1:4, 1:5 and 1:6 as fine aggregate. Sand is replaced by ISF slag at substitution intervals of 25% from 0 to 100%. A comparison of compressive strength of these mortars mixes has been made. It was observed, for richer mixes compressive strength increased to 120% of the control mix for 50% substitution. Similarly, trial mixes with 50% slag were tested with addition of marble dust replacing natural sand in the range of 10 to 50%. It was observed that, combination of marble dust with ISF slag resulted in maintaining the 20% higher compressive strength achieved earlier for the 50% substitution of ISF slag.

Long-Run Variation in Capacity Utilization in the Presence of a Fixed Normal Rate

We develop a generic Kalecki-Robinson model of growth that, subject to different closures, illustrates the different channels through which the economy can adjust to a change in demand conditions in the long run. The closures are shown to have different implications for the behaviour of the rate of capacity utilization and hence whether and how the economy achieves a “fully-adjusted position” (equalization of the actual and normal rates of capacity utilization). Assuming that the normal rate of capacity utilization is exogenously fixed, it is then shown that variation in the actual capacity utilization rate can nevertheless occur – at least within limits – without triggering “Harrodian instability”. This result emanates from a discontinuity in the investment function that is grounded in Harrod’s own macrodynamics, so that it is ultimately the combination of Harrodian and Kaleckian dynamics that gives rise to long-run variations in the actual rate of capacity utilization in the presence of a fixed normal rate. Aggregate and industry-level US capacity utilization data are then used to calculate possible bands within which the rate of capacity utilization may vary without triggering Harrodian instability. A key finding is that the conditions necessary for the latter appear to be relatively rare.

Utilization of Biologics in Saskatchewan

Background Few details are available about the factors driving cost increases of biologic medications. Objectives To describe trends in utilization and cost of biologic agents using administrative databases in Saskatchewan, Canada. Methods Two analyses were conducted. First, aggregate utilization of biologics based on prescriptions dispensed was measured in each calendar year between 2001 and 2013. Second, a retrospective cohort of new biologic users was created to examine trends in spending between 2001 and 2013. During the first year of biologic therapy, biologic cost was quantified for each specific biologic agent as: (a) total spending; (b) total mil - ligrams dispensed; and (c) estimated unit cost (i.e., total cost in 2013 $CAD divided by total milligrams dispensed during the year). Data analyses were descriptive and all biologic costs were adjusted to 2013 dollars (CAD). Results In the first year of biologic availability in Saskatchewan (2001), 133 patients were dispensed at least one biologic agent for a total cost of $0.5 million. In 2013, 2,402 biologic recipients were identified for a total cost of $51.8 million. Almost all of these biologic costs (88.9%) were paid by the provincial government. In 2013, infliximab was the most frequently used agent, accounting for 46.5% of all spending on biolog - ics. Infliximab was also the most expensive agent in 2013 (mean cost $31,340 ± 15,307) and showed the highest increase in the mean yearly cost over time due to greater quantities dispensed. Conclusion Biologic utilization will require ongoing monitoring to optimize patient-level and societal-level benefits.

Analyzing the correlation between commuting satisfaction and travelling utility

Abstract The interest for travel satisfaction has rapidly grown during the past two decades. Since the development of Discrete Choice Theory, doing a trip was mostly described as a pure derived activity without utility per se but nowadays many scholars have demonstrated that individuals might be satisfied in performing the trip itself. However, little is still known on the relation between the travelling utility and the stated satisfaction for a specific trip. The objective of this paper is to analyse the relation between the stated commuting satisfaction and the utility of the associated trip thanks to the Logsum function, which is often used to represent the aggregated utility of a set of travel alternatives. The results of a travel survey implemented at the University of Luxembourg in 2012, show that the utility function, expressed through its Logsum, is positively correlated with the stated commuting satisfaction. While the Logsum function of the travelling utility might, to some extent, approximate the travelling satisfaction, some variations in the correlation magnitude, due to context particularities and socio-demographic attributes, are observed and discussed in this study.

Influence of recycled concrete aggregates on the engineering and durability properties of alkali activated slag concrete

The environmental effects of production of cement have provoked to examine the growth of concrete with 100% replacement of cement with materials which are activated by alkali solutions. Alkali activated slag (AAS) concrete is eco-friendly and potentially deemed to be a division of sustainable process. As majority of the volume of concrete is consumed by aggregates, there is a necessary to decrease the utilization of natural aggregates resulting in reduction of exploiting natural resources and effective utilization of construction and demolition waste. The effect of recycled concrete aggregate (RCA) on the engineering and durability properties of alkali activated slag concrete (AASC) under ambient curing state has been investigated in this paper. Since, very few works were carried in the field of alkali activated slag concrete curing under ambient temperature state and the utilization of recycled aggregates, an investigation was performed in AASC mixes with varying RCA fraction to study their influence on strength (compressive, splitting tensile and flexural) and durability (absorption, sorptivity, chloride and sulphate exposure) properties of AASC. The outcome of the results concludes that the addition of RCA has no signification reduction in the properties of alkali activated slag concrete.

Aggregate transport and utilization: ecological footprint and environmental impacts

The Ecological Footprint (EF) measures how much of the biosphere’s annual regenerative capacity is required to renew the natural resources used by a defined population in a given year. In essence, the EF is a resource accounting tool that measures how much biologically productive land and sea is used by a given population or activity, and compares this with the available land and sea.Productive land and sea support population demands for food, fiber, timber, energy, and space for infrastructure. These areas also absorb gaseous emissions (i.e. CO2) generated from human activities.The present paper discusses a methodology that allows the parametric estimation of the EF due to the transport of aggregates to urban areas as a function of tonnage and distance.

Influence of the ceramic recycled agreggates in the masonry mortars properties

In this study the influence of the utilization of ceramic recycled aggregates in the properties of masonry mortars is analyzed. The mortars were made with an initial relation cement–sand of 1: 6. The recycled aggregate used was added to the mixture in percentages of replacement of 20%, 35%, 50%, 70% and 100% of natural aggregate. The substitutions were made in volume. All manufactured specimens were cured for 28days under standard conditions. Once the curing period was completed the physical and mechanical properties were analyzed.After analyzing the results obtained in the tests a reduction in the density is observed as the percentage of substitution increases. Also, its behavior to flexion improves, the compressive strength is increased and the coefficient of water absorption is reduced. The shrinkage can be considered acceptable up to percentages of replacement of 50%.

Aggregation with a mix of indivisible and continuous labor supply decisions

Purpose The purpose of this paper is to explore the problem of non-convex labor supply decision in an economy with both discrete and continuous labor decisions. In contrast to the setup in McGrattan et al. (1997), here each household faces an indivisible labor supply choice in the market sector, while it can choose to work any number of hours in the non-market sector. Design/methodology/approach The authors show how lotteries as in Rogerson (1988) can again be used to convexify consumption sets, and aggregation over individual preferences. Findings With a mix of discrete and continuous labor supply decisions, disutility of non-market work becomes separable from market work, and the elasticity of the latter increases from unity to infinity. Research limitations/implications As a possible venue for future research, the authors plan to feed the derived aggregate utility function above in a sophisticated real-business-cycle model to investigate the effect of those preferences for the transmission of technology and fiscal shocks. Originality/value This is a novel and interesting result in the aggregation literature.

Utility-Optimal Resource Management and Allocation Algorithm for Energy Harvesting Cognitive Radio Sensor Networks

In this paper, we study resource management and allocation for energy harvesting cognitive radio sensor networks (EHCRSNs). In these networks, energy harvesting supplies the network with a continual source of energy to facilitate the self-sustainability of the power-limited sensors. Furthermore, cognitive radio enables access to the underutilized licensed spectrum to mitigate the spectrum-scarcity problem in the unlicensed band. We develop an aggregate network utility optimization framework for the design of an online energy management, spectrum management, and resource allocation algorithm based on Lyapunov optimization. The framework captures three stochastic processes: energy harvesting dynamics, inaccuracy of channel occupancy information, and channel fading. However, a priori knowledge of any of these processes statistics is not required. Based on the framework, we propose an online algorithm to achieve two major goals: first, balancing sensors’ energy consumption and energy harvesting while stabilizing their data and energy queues; second, optimizing the utilization of the licensed spectrum while maintaining a tolerable collision rate between the licensed subscriber and unlicensed sensors. The performance analysis shows that the proposed algorithm achieves a close-to-optimal aggregate network utility while guaranteeing bounded data and energy queue occupancy. The extensive simulations are conducted to verify the effectiveness of the proposed algorithm and the impact of various network parameters on its performance.

Efficient Algorithm for Scalable Event-Based Demand Response Management in Microgrids

Demand response management has become one of the key enabling technologies for smart grids. Motivated by the increasing demand response incentives offered by service operators, more customers are subscribing to various demand response programs. However, with growing customer participation, the problem of determining the optimal loads to be curtailed in a microgrid during contingencies within a feasible time frame becomes computationally hard. This paper proposes an efficient approximation algorithm for event-based demand response management in microgrids. In event-based management, it is important to curtail loads as fast as possible to maintain the stability of a microgrid during the islanded mode in a scalable manner. A simple greedy approach is presented that can rapidly determine a close-to-optimal load curtailment scheme to maximize the aggregate customer utility in milliseconds for a large number of customers. This paper further derives a novel theoretical guarantee of the gap between the proposed efficient algorithm and the optimal solution (that may be computationally hard to obtain). The performance of algorithm is corroborated extensively by simulations with up to thousands of customers. For the sake of practicality, the proposed event-based demand response management algorithm is applied to a feeder from the Canadian benchmark distribution system. The simulation results demonstrate that the proposed approach efficiently optimizes microgrid operation during islanded mode while maintaining appropriate voltage levels and network constrains.

Preliminary Assessment of Durability of Sustainable RC Structures with Mixed-In Seawater and Stainless Steel Reinforcement

The massive use of natural resources such as fresh water or virgin rock for aggregates in the construction industry originates the need for possible alternative solutions aimed at the environmental sustainability, as, for instance, the use of chloride-contaminated raw materials for the production of concrete. In the framework of a research project financed by the Infravation Program (Advanced systems, materials and techniques for next generation infrastructure), an experimental study is undertaken aiming at demonstrating the safe utilization of seawater and salt-contaminated aggregates (natural or recycled) for a sustainable concrete production when combined with non-corrosive reinforcement to construct durable and economical concrete infrastructures. Considering the lack of sufficient fresh water in many regions of the world, this paper focuses on a preliminary evaluation of the possibility of replacing fresh water used to mix/cure concrete with seawater, combined with different types of stainless steel reinforcement. Based on literature data and the performance-based approach of “Model Code for Service Life Design” published by the International Federation for Structural Concrete (fib), risks associated with the use of using seawater in relation to the service life a reinforced concrete element in a marine environment are investigated. During the development of the project, laboratory and field tests will allow for the collection of experimental data to better define the durability evaluation and analyse advantages of the proposed approach in terms of life cycle assessment.

Revealing Utilization at Internet Interconnection Points

Recent Internet interconnection disputes have sparked an increased interest in developing methods for gathering and collecting data about utilization at interconnection points. One mechanism, developed by DeepField Networks, allows Internet service providers (ISPs) to gather and aggregate utilization information using network flow statistics, standardized in the Internet Engineering Task Force as IPFIX. This report (1) provides an overview of the method that DeepField Networks is using to measure the utilization of various interconnection links between content providers and ISPs or links over which traffic between content and ISPs flow; and (2) surveys the findings from five months of Internet utilization data provided by seven participating ISPs — Bright House Networks, Comcast, Cox, Mediacom, Midco, Suddenlink, and Time Warner Cable — whose access networks represent about 50% of all U.S. broadband subscribers.We first discuss the problem of interconnection and utilization at interconnection points. We then discuss the basic operation of the measurement capabilities, including the collection and aggregation of traffic flow statistics (i.e., IPFIX records), providing an assessment of the scenarios where these aggregate measurements can yield accurate conclusions, as well as caveats associated with their collection. We assess the capabilities of flow statistics for measuring utilization, and we discuss the capabilities and limitations of the approach the aggregation techniques that the ISPs use both in providing data to us, and that we apply before making the data public.The dataset includes about 97% of the paid peering, settlement-free peering, and ISP-paid transit links of each of the participating ISPs. Initial analysis of the data — which comprises more than 1,000 link groups, representing the diverse and substitutable available routes — suggests that many interconnects have significant spare capacity, that this spare capacity exists both across ISPs in each region and in aggregate for any individual ISP, and that the aggregate utilization across interconnects is roughly 50% during peak periods.

Possibilities of Utilization of Aggregates and Extractive Waste from Hard Coal Mining at Janina Mine in the Process of Reclamation of Open-pit Mines

AbstractIn recent years, the economic importance of gangue mined during coal production has changed and it is currently treated more and more often not as waste but as a source of mineral resources for economic use. The overriding objective throughout the reclamation process of open-pit mines associated with the utilization of external material is to make sure that the placement of waste rock on the surface does not cause damage to the environment. The paper presents results of the diagnosis and evaluation of the possibility of filling open-pit mine workings with mining waste or other materials, for example aggregates produced on the basis of gangue, originating in the Janina Mine mining plant (a subsidiary of TAURON Wydobycie S.A.). The study involved aggregate or coal silts from dewatering on the filter presses. The evaluation refers to the legal aspects and takes the requirements of pollution prevention into account, with a particular emphasis on soil, surface water and groundwater. The analysis of the potential impact on the soil and water environment of the project involving reclamation of the open-pit excavation with the use of minerals or waste from coal mining was carried out based on a study of the total content of sulfur and other elements in the samples pierwiastków (As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, V and Zn), as well as of the leaching of components. Moreover, an examination of the coefficient of permeability and porosity was conducted, which allowed the suitability of the material for the construction of insulating layers to be determined. The physical and chemical analyses were conducted on a total of over a dozen samples of waste rock, a byproduct of the enrichment of coal in the Janina Mine plant. The specific studies of the total sulfur content were conducted for the 16 primary samples scattered into 15 fractions each. Moreover, the so-called secondary samples were created, meaning that fine fractions of less than 20 mm and less than 10 mm were rejected. The total content of the selected components was examined for such crafted samples and their concentrations were determined in the leachable form (batch test 1:10). In the case of use of waste rock as an aggregate for quarry reclamation, a comparative analysis was applied to the legal requirements assigned to the mining waste and the quality of soil and water environment. Based on the conducted studies, it has been concluded that the coal silts (filter cakes) are characterized by good insulating properties and can be used for waterproofing objects, especially in the industrial, communications and mining areas. However, coal silts do not meet the quality requirements, mainly due to their slightly increased chlorides content, in addition to being a waste, which in some cases limits the possibility of their use. The best quality parameters were found for the gangue from the Janina Mine (on the basis of which aggregates are manufactured), but deprived of fine fractions. Physical and chemical analyses of the total content of elements in the secondary samples showed that the obtained values are within the allowable ranges determined by appropriate regulations for the vast majority of samples. The limit of 1% was assumed for the sulfur content. The conducted research on the leaching of pollutants indicates that the tested samples do not introduce contaminants exceeding the limit values for the analyzed metals and sulfates. Only single exceedances of the analyzed parameters are observed. The test results allow to conclude that it is possible to obtain a useful product that meets the requirements of environmental protection, but only after the rejection of fine fractions of the waste material.

An optimal content caching framework for utility maximization

For desirable quality of service, content providers aim at covering content requests by large network caches. Content caching has been considered as a fundamental module in network architecture. There exist few studies on the optimization of content caching. Most existing works focus on the design of content measurement, and the cached content is replaced by a new one based on the given metric. Therefore, the performance for service provision with multiple levels is decreased. This paper investigates the problem of finding optimal timer for each content. According to the given timer, the caching policies determine whether to cache a content and which existing content should be replaced, when a content miss occurs. Aiming to maximize the aggregate utility with capacity constraint, this problem is formalized as an integer optimization problem. A linear programming based approximation algorithm is proposed, and the approximation ratio is proved. Furthermore, the problem of content caching with relaxed constraints is given. A Lagrange multiplier based approximation algorithm with polynomial time complexity is proposed. Experimental results show that the proposed algorithms have better performance.

Managing Contingencies in Smart Grids via the Internet of Things

This paper proposes a framework for contingency management using smart loads, which are realized through the emerging paradigm of the Internet of things. The framework involves the system operator, the load serving entities (LSEs), and the end-users with smart home management systems that automatically control adjustable loads. The system operator uses an efficient linear equation solver to quickly calculate the load curtailment needed at each bus to relieve congested lines after a contingency. Given this curtailment request, an LSE calculates a power allowance for each of its end-use customers to maximize the aggregate user utility. This large-scale NP-hard problem is approximated to a convex optimization for efficient computation. A smart home management system determines the appliances allowed to be used in order to maximize the user’s utility within the power allowance given by the LSE. Since the user’s utility depends on the near-future usage of the appliances, the framework provides the Welch-based reactive appliance prediction (WRAP) algorithm to predict the user behavior and maximize utility. The proposed framework is validated using the New England 39-bus test system. The results show that power system components at risk can be quickly alleviated by adjusting a large number of small smart loads. Additionally, WRAP accurately predicts the users’ future behavior, minimizing the impact on the aggregate users’ utility.

A closed-loop life cycle assessment of recycled aggregate concrete utilization in China

This paper studies the potential environmental impact of recycled coarse aggregate (RCA) for concrete production in China. According to the cradle-to-cradle theory, a closed-loop life cycle assessment (LCA) on recycled aggregate concrete (RAC) utilization in China with entire local life cycle inventory (LCI) is performed, regarding the environmental influence of cement content, aggregate production, transportation and waste landfilling. Special attention is paid on the primary resource and energy conservation, as well as climate protection induced by RAC applications. Environmental impact between natural aggregate concrete (NAC) and RAC are also compared. It is shown that cement proportion and transportation are the top two contributors for carbon dioxide (CO2) emissions and energy consumption for both NAC and RAC. Sensitivity analysis also proves that long delivery distances for natural coarse aggregate (NCA) leave a possible opportunity for lowering environmental impact of RAC in China.

Vector Coprocessor Virtualization for Simultaneous Multithreading

Vector coprocessors (VPs), commonly being assigned exclusively to a single thread/core, are not often performance and energy efficient due to mismatches with the vector needs of individual applications. We present in this article an easy-to-implement VP virtualization technique that, when applied, enables a multithreaded VP to simultaneously execute multiple threads of similar or arbitrary vector lengths to achieve improved aggregate utilization. With a vector register file (VRF) virtualization technique invented to dynamically allocate physical vector registers to threads, our VP virtualization approach improves programmer productivity by providing at runtime a distinct physical register name space to each competing thread, thus eliminating the need to solve register-name conflicts statically. We applied our virtualization technique to a multithreaded VP and prototyped an FPGA-based multicore processor system that supports VP sharing as well as power gating for better energy efficiency. Under the dynamic creation of disparate threads, our benchmarking results show impressive VP speedups of up to 333% and total energy savings of up to 37% with proper thread scheduling and power gating compared to a similar-sized system that allows VP access to just one thread at a time.

Cat Bond Spreads: A New Model with an Empirical Validation Using Nonparametric Tests

Previous empirical studies on catastrophe (CAT) bond premium calculations rely almost exclusively on actuarial models, and usually compare their accuracy strictly in terms of in-sample t and predictive power. We contribute to this literature by deriving a utility-based specification for pricing CAT bonds under Hyperbolic Absolute Risk Aversion (HARA), and by proposing two specification tests that use nonparametric estimation techniques to test simultaneously for all possible mis-specifications. Various pricing models are then estimated and tested with data from the primary market for CAT bonds. Our results suggest that the utility-based model we propose not only is well-suited for explaining the risk-return relationship observed in the CAT bond market but also delivers the best performance among the tested models. We also provide new empirical evidence that the aggregate utility function of CAT investors exhibits decreasing absolute risk aversion.