Heterogeneous Commodity Research Articles

Hub-and-spoke maritime network with heterogeneous commodity on island shipping

ABSTRACT This paper presents an extension to a classic hub-and-spoke maritime network, by adding the feeder node and heterogeneous commodity to the network on an island shipping network. The cargo is delivered from origin (hub) to destination (feeder), which can be compounded in hub node and sent using container in container ship to a spoke node. In the spoke node, the container is de-containerized into general cargo package, representing heterogeneous commodity, and finally shipped using cargo ship to the feeder node. This system is suitable for island shipping network, consisting of several small ports with marginal hinterland, where the development of container facility is not financially feasible. The proposed model generates the optimum number and location of spoke, alongside with its allocated feeder node, to minimize the total shipping cost. As a case study, an actual island network in Southeast Sulawesi, Indonesia, is utilized, resulting in a recommendation of one additional spoke to the existing network. The result also suggests a backup spoke if the single spoke scheme is selected, anticipating any disruption on the selected spoke node. A trade-off between shipping cost reduction and spoke investment cost should be considered by policymakers in the adoption of the system.

Commodity price effects on currencies

Using quarterly data on four commodity-exporting countries, we examine the explanatory power of real commodity prices to predict real effective exchange rates, paying particular attention to the separate roles of varied sectoral commodity prices during alternative time periods. We determine that the commodity price effect is nonuniform across countries and commodity sectors and varies over time. The use of fixed-weight price indexes or nominal exchange rates and commodity prices yields heterogeneous commodity price effects. Furthermore, the pattern of commodity price effects is influenced by the presence of macroeconomic conditions, effects of crises, and exchange rates of leading trading partners. These empirical results highlight the challenges associated with explaining diverse currency behaviors across different time periods using a single commodity-price-based exchange rate model. In addition, these findings suggest policymaking assuming stable commodity price effects difficult.

Conditional feeder cattle hedge ratios: Cross hedging with fluctuating corn prices

Feeder cattle are a heterogeneous commodity whose prices differ in important ways relative to the cattle specified in the CME Group Feeder Cattle futures contract. This necessitates estimation of optimal feeder cattle hedge ratios to manage price risk. Corn price is an important and often overlooked consideration when estimating feeder cattle hedge ratios. Corn price impacts feeder cattle weight-price slides and associated hedge ratios, which can result in over- or under-hedging. Utilizing transaction data from four feeder cattle markets, we estimate hedge ratios conditioned on corn price and compare risk of using corn-conditioned hedge ratios to using hedge ratios not dependent on corn price. Feeder cattle hedge ratios vary substantially across time, sex, location, and weight, which necessitates more frequent and detailed hedge ratio estimation. However, hedging risk is not generally statistically or economically significantly reduced by using corn-conditioned hedge ratios.

A survey on load balancing algorithms for virtual machines placement in cloud computing

SummaryThe emergence of cloud computing based on virtualization technologies brings huge opportunities to host virtual resource at low cost without the need of owning any infrastructure. Virtualization technologies enable users to acquire, configure, and be charged on pay‐per‐use basis. However, cloud data centers mostly comprise heterogeneous commodity servers hosting multiple virtual machines (VMs) with potential various specifications and fluctuating resource usages, which may cause imbalanced resource utilization within servers that may lead to performance degradation and service level agreements violations. So as to achieve efficient scheduling, these challenges should be addressed and solved by using load balancing strategies, which have been proved to be nondeterministic polynomial time (NP)‐hard problem. From multiple perspectives, this work identifies the challenges and analyzes existing algorithms for allocating VMs to hosts in infrastructure clouds, especially focuses on load balancing. A detailed classification targeting load balancing algorithms for VM placement in cloud data centers is investigated, and the surveyed algorithms are classified according to the classification. The goal of this paper is to provide a comprehensive and comparative understanding of existing literature and aid researchers by providing an insight for potential future enhancements.

On asynchronous parallelization of order-based GA over grid-enabled heterogenous commodity hardware

In real-world applications, the runtime of genetic algorithms (GAs) can be computationally demanding, an issue that can be mitigated using parallelization. The study evaluates the parallelization of order-based GAs using the island model in an asynchronous heterogeneous computing environment. The island model allows for a considerable number of migration topologies. The study offers a systematic review of the studies on migration topologies and observes that no study is available yet on the performance of these migration topologies over asynchronous heterogeneous environments. Based on a statistical analysis of a comprehensive set of experiments, using real-world TSPLIB instances, the study researches the question: What is the fastest island model topology for order-based genetic algorithm, in an asynchronous distributed heterogeneous grid-enabled commodity computing environment, without losing significant fitness comparatively to the correspondent sequential panmictic implementation of the same algorithm?. Moreover, a new speedup index, the expected root speedup, is also proposed. A diversity of topology types and characteristics are considered: the single node, star, ring, cartwheel, rooted ordered tree, rooted full binary tree, coordinated tree-ring, and feedforward fully connected layered type. Different number of nodes are also considered. While some of the types of topologies are well known, the coordinated tree-ring topology is a novelty. These types of topologies allow us to assess three notable cases: (i) no migration (isolated island), (ii) migration toward the coordinator only, and (iii) migration flows to, and from, the coordinator.

Analyzing Google Earth application in a heterogeneous commodity cluster display wall

Nowadays, clusters of interconnected workstations have become a common solution for powering large composite displays, or “cluster display walls”, to visualize high resolution images. Our paper is focused on analyzing a specific cluster display wall developed by Google, named Liquid Galaxy, made up of heterogeneous commodity hardware with different degrees of heterogeneity, running master-slave (Google Earth) and client-server (Quake III Arena) multimedia applications. With this in mind, we define and test different scenarios, representing the behavior of many kinds of users. Our results show that the CPU, memory and network are good enough to execute the client-server application, while, depending on the user behavior, the external network constitutes the bottleneck of the system in Google Earth. So, the master-slave application has focused our attention. Likewise, in order to analyze the users’ point of view when interacting with Google Earth in the Liquid Galaxy, we define a new metric, named Visualization Rate (VR), which enables a relationship to be established between the user experience and the platform performance. In order to set the minimum acceptable value of the VR parameter according to users perception, we carried out different tests with real users. Then, this minimum threshold was compared with the VR value obtained from the automated benchmarking performed afterwards on clusters with different heterogeneity degrees. Finally, we analyzed the VR trend when the Liquid Galaxy is scaled from 3 up to 8 nodes in both the homogeneous and heterogeneous architectures to study the scalability of the system.

Agent-based load balancing in Cloud data centers

Cloud data centers are generally composed of heterogeneous commodity servers hosting multiple virtual machines (VMs) with potentially different specifications and fluctuating resource usages. This may cause a resource usage imbalance within servers that may result in performance degradation and violations to service level agreements. This work proposes a collaborative agent-based problem solving technique capable of balancing workloads across commodity, heterogeneous servers by making use of VM live migration. The agents are endowed with (i) migration heuristics to determine which VMs should be migrated and their destination hosts, (ii) migration policies to decide when VMs should be migrated, (iii) VM acceptance policies to determine which VMs should be hosted, and (iv) front-end load balancing heuristics. The results show that agents, through autonomous and dynamic collaboration, can efficiently balance loads in a distributed manner outperforming centralized approaches with a performance comparable to commercial solutions, namely Red Hat, while migrating fewer VMs.

A critical assessment of the HGCA grain sampling guide

Author Summary: HGCA’s grain sampling guide is assessed with respect to the principles for representative sampling as set forward in the Theory of Sampling (TOS). Sampling correctness, which requires the elimination of all Incorrect Sampling Errors (ISE), constitutes the only guarantee for valid, representative grain quality control; presence of ISEs causes a varying, uncontrollable sampling bias that cannot be corrected for. Contrary to a first superficial observation (“grain is grain”), many different species and varieties, as well as differences caused by soil types, availability of local nutrients, make “grain” a significantly heterogeneous commodity, which requires special attention when sampled at various process locations (from harvesting, storage until commercial intake). The present appraisal shows that most of the respected HGCA grain guide’s recommendations do not comply with TOS principles of sampling correctness. The suggested sampling procedures constitute major error potentials, which strongly compromise sample representativity.

Smart Operation of Smart Grid: Risk-Limiting Dispatch

The drastic reduction of carbon emission to combat global climate change cannot be realized without a significant contribution from the electricity sector. Renewable energy resources must take a bigger share in the generation mix, effective demand response must be widely implemented, and high-capacity energy storage systems must be developed. A smart grid is necessary to manage and control the increasingly complex future grid. Certain smart grid elements-renewables, storage, microgrid, consumer choice, and smart appliances-increase uncertainty in both supply and demand of electric power. Other smart gird elements-sensors, smart meters, demand response, and communications-provide more accurate information about the power system and more refined means of control. Simply building hardware for renewable generators and the smart grid, but still using the same operating paradigm of the grid, will not realize the full potential for overall system efficiency and carbon reduction. In this paper, a new operating paradigm, called risk-limiting dispatch, is proposed. It treats generation as a heterogeneous commodity of intermittent or stochastic power and uses information and control to design hedging techniques to manage the risk of uncertainty.

Performance-based dynamic loop scheduling in heterogeneous computing environments

With the rapid advance of computing technologies, it becomes more and more common to construct high-performance computing environments with heterogeneous commodity computers. Previous loop scheduling schemes were not designed for this kind of environments. Therefore, better loop scheduling schemes are needed to further increase the performance of the emerging heterogeneous PC cluster environments. In this paper, we propose a new heuristic for the performance-based approach to partition loop iterations according to the performance weighting of cluster/grid nodes. In particular, a new parameter is proposed to consider HPCC benchmark results as part of performance estimation. A heterogeneous cluster and grid were built to verify the proposed approach, and three kinds of application program were implemented for execution on cluster testbed. Experimental results show that the proposed approach performs better than the previous schemes on heterogeneous computing environments.

Special section: Grid/distributed computing systems security

We are delighted to present to you the special section of Future Generation Computer Systems (FGCS) on grid/distributed computing systems security. This special section contains five technical papers dealing with cutting-edge research and technology related to the design,modeling, and implementation of architectures, algorithms and protocols of computer systems or environments. In the paper ‘‘Secure verifiable non-interactive oblivious transfer protocol using RSA and bit commitment in a distributed environment’’, Soongohn Kim et al. analyze the basic concept of an OT (Oblivious Transfer) protocol for exchanging secret information fairly, survey the basic idea of an interactive and secure noninteractive OT protocol, and present a new non-interactive type of OTprotocolwhich is verifiable. The amount of traffic of transferring information of the suggested method is less than or equal to that of the conventional interactive method. The paper ‘‘Structure design and test of an enterprise security management system with advanced internal security’’ by Seoksoo Kim et al., analyzes existing enterprise security management systems and, on the basis of the results, proposes and tests an enterprise security management system with reinforced internal security. For the test, the authors used a firewall through log analysis and designed Intranet work using a virtual IP system. J. H. Abawajy proposes a new two-level adaptive space-sharing scheduling policy for non-dedicated heterogeneous commodity-

Quantum Chemical Calculations by Parallel Computer from Commodity PC

Computational quantum chemistry helps us to determine, calculate, and study new concepts, compounds, reactions and mechanisms. Such way is very useful with compounds that require exceptionally care in their handling, such as explosives, decreasing risk to persons testing and maintenance costs in service. Computational quantum chemistry is the ground of molecular modeling, on prediction the behavior of individual molecules within a chemical system. The molecular modeling let us to obtain the molecular characteristics comparable with experimental date. In this way the molecular structures of for positional isomers of 2,4,6-trinitrotoluene (TNT) were calculated by an ab initio HF/6-31G∗ method using self made local area personal computer (PC) cluster TAURAS. The cluster was made from heterogeneous commodity hardware of teaching class and for high performance computing (HPC) was used the SCore cluster system software developed in Japan. The structure and the features of the cluster are described and the performance is evaluated during solving of linear algebra testing tasks. During the determination of the structures of the positional isomers of TNT, the deformation of the phenyl ring and the distortions of the nitro and methyl groups were concern. The calculations confirmed that both of these were affected by the positions of nitro groups. A comparison of the calculated energies of all the isomers revealed the tendency to form the stable isomers when the close contact effects of the nitro groups were reduced.

Demand for Housing in Tokyo: A Discrete Choice Analysis

Tiwari P. and Hasegawa H. (2004) Demand for housing in Tokyo: a discrete choice analysis, Reg. Studies 38, 27–42. Housing is a commodity which is a bundle of characteristics specific to a housing market, tenure, income and other household characteristics. Voluminous literature exists on housing demand in which a quantitative measure defined as housing services is used to measure housing demand. Housing or, more precisely, the service stream from a housing unit, is a heterogeneous commodity. Some dimensions, such as age or size of structure, are measured on a continuous scale; others, such as tenure or type of structure, are discrete properties. Measuring the volume of housing services as housing expenditure, as is done in previous research, essentially ignores the heterogeneity, and, for large number of policy purposes like impact of tax on tenure choice, choice between owning and renting, etc., the distribution of housing consumption into qualitatively different categories, is of more interest than an aggregate qualitative measure of housing expenditure alone. Earlier research has addressed the issues of methodologies in housing demand estimation and different market and related differences in demand elasticities. The econometric theory of joint discrete/continuous models is well studied, and there exist a variety of applications. However, there is a paucity of research applications to analyse housing demand using discrete models. The limited research in this area has focused only on American or German housing markets. There is no research on housing markets, which treats housing demand as discrete choices for Japan, despite the economic importance of the Japanese economy. We model housing demand in Japan using a discrete choice model. A nested multinomial logit model (NMNL) is the basic analytical tool for our analysis. The microeconomic and econometric foundations of NMNL models encompass the elegant theory of housing economics of a utility maximizing household. NMNL models impose a hierarchical structure on the choice set that can be visualized in the form of a decision tree. Three dimensions of choice, tenure, dwelling size (as number of rooms) and structure type (as type of unit) generate these steps of clustering. This paper estimates the choice probabilities and demand elasticities of various housing alternatives for Tokyo using 1993 housing survey data for 23 wards.

Incorrect Price Information for a Heterogeneous Commodity: A Conceptual Synthesis

AbstractTheory and analysis of markets and market behavior have typically assumed that the information available to market participants is correct. Additionally, most analyses examine market behavior assuming homogeneous products. This article examines the implications of incorrect market price information, especially price differentials based on quality, first conceptually and then with evidence from prior research on cotton prices as an illustration. This evidence shows that price differences based on quality have direct implications on production and marketing processes. Incorrect price/quality information can lead to distortions in the market and market inefficiency.

A study on the estimation and aggregation of disaggregate models of mode choice for freight transport

Abstract The literature on modal choice analysis of freight transport has revealed that the freight transport market is highly diverse. Aggregation over heterogeneous commodity types can cause a bias in the estimation of models. Therefore, disaggregation over commodity groups has been the norm and different models developed. In some cases, however, aggregate models might be preferable because they are less costly and may be adequate for prediction. The present paper attempts to improve our understanding of this area by investigating the desirability of aggregation over commodity groups.

Export pricing in state-owned and private MNEs: Evidence from the international petroleum market

This paper undertakes a comparison of firm conduct, examining prices charged for crude oil by state-owned and private petroleum companies. The literature that compares public and private enterprise has tended to focus on local monopolies, and their profitability and technical efficiency. The behavior of public and private firms in competition with each other, however, has received little theoretical and virtually no empirical attention. In contrast to the literature, this paper presents an industry case-study. We conduct tests on the differences between prices for crude oil, a heterogeneous commodity with no centralized market, taking advantage of an unusual micro-database of individual import transactions. There is little evidence of difference between prices obtained by private and state-owned multinational enterprises.

On the fair division of a heterogeneous commodity

Consider a heterogeneous but divisible commodity, bundles of which are represented by the (measurable) subsets of the good. One such commodity might be land. The mathematics literature has considered agents with utilities that are nonatomic measures over the commodity (and hence are additive). The existence of ‘α-fair’ allocations, in which each agent receives a utility proportional to his utility of the endowment of the entire economy, was demonstrated there. Here we extend these existence results to α-fair efficient allocations, envy-free allocations, envy-free efficient allocations, group envy-free and nicely shaped allocations of these types. We examine utilities that are not additive and relate the mathematics literature to the economics literature. We find sufficient conditions for the existence of egalitarian-equivalent efficient allocations. Finally, we consider the problem of allocating a time interval (uses of a facility). Existence of an envy-free allocation had been demonstrated in earlier literature. We show that any envy-free allocation is efficient as well as group envy-free. We extend this last result to a more general setting.

Measuring international competitiveness in the beef sector

Beef is a heterogeneous commodity, which makes it difficult to compare beef prices in an international level. This paper evaluates several methods of comparing beef prices to be used in measuring both comparative advantage and protection. The most suitable method is one that compares the prices of wholesale cuts, adjusted for transportation costs.

The Efficiency of Housing Search

Previous research in the housing market has largely focused on housing market outcomes (e.g., the quantity of housing services demanded or supplied or the determination of equilibrium prices); scant attention has been directed at the processes producing these outcomes. Recently, economists have developed models of buyer and seller search processes in housing markets [6; 22], but almost no empirical testing of these models has been done.' The importance of search in economic markets has been discussed by Lippman and McCall [15]. The difficulties encountered by deterministic theories of economic markets in explaining different prices for identical commodities and persistent positive levels of unemployed resources are overcome when search is introduced. Search may be of even greater importance in housing markets than in most other economic markets. Housing generally accounts for the largest item of consumption for most households; for homeowners, housing is usually the household's largest asset. Housing is a heterogeneous commodity that is traded in highly decentralized markets.2 The costs of moving can be substantial, reducing the gains from relocation. The consumption of housing also involves externalities that add to the heterogeneity of the consumption bundle. Finally, recent theoretical work by Courant [6] suggests that the rational search behavior of households facing discrimination in housing markets might act to perpetuate adverse market conditions facing such households. Given the importance of housing as a consumption commodity and as an asset and the above characteristics of housing and housing markets, previous descriptive examinations

Alternative Techniques for Developing Real Estate Price Indexes

T HE rapid rate of increase in the prices of houses in recent years has resulted in renewed interest in trends in residential real estate. A widely quoted study by the Harvard-MIT Joint Center for Urban Studies (Solomon, et al., 1977) showed that in 1976 only 27% of families could afford to buy the median priced new home, a significant change from 1970 when 46% of families were able to make such a purchase. Such rapid changes could result in significant income redistribution effects, and policy proposals have been numerous. To assess these trends and proposals, it is necessary to have accurate methods of developing residential real estate price indexes. Most real estate indexes have been based on the average or median selling price in each year for new or used houses. Yet there may exist substantial differences in the houses on the market at different times, so such indexes contain quality changes as well as pure price changes. Because housing is a highly heterogeneous commodity, the measurement of quality-adjusted price changes has proven difficult. Such measurement is desirable not simply because of the recent significant price changes in the real estate market, but also because economists have found property values to be one of the best sources of information on goods for which markets do not exist. Although in the past cross-sectional studies have generally been used for this purpose, questions remain concerning the timing of the impacts. Comparisons of real estate price indexes can provide insights into the dynamics of such effects. Among the techniques suggested for developing quality-adjusted price indexes, approaches using hedonic regressions and repeat-sale regressions appear to be the most promising. In this paper, alternative local price indexes are developed using modifications of the hedonic and repeat-sale techniques. For the case considered, the two independent techniques provide statistically identical indexes of the real price of housing. The estimated rate of increase in house prices using the hedonic and repeat-sale techniques is substantially lower than the non-quality adjusted rate implied by the change in average selling price.