Allocation Step Research Articles

Seismic vulnerability of bridges in transport networks subjected to environmental deterioration

This paper investigates the problem of management, maintenance and planning of interventions in transport networks located in seismic zones, in relation to the actual state of degradation of their most vulnerable elements, as bridges. The study consists in two phases: the first phase is concerned with definition of the seismic vulnerability of a typical bridge in the network, through the construction of fragility curves calculated taking into account the corrosion of the reinforcing steel as the main cause of environmental deterioration. Once the fragility curves of the deteriorated bridges are computed, the second phase consists in the analysis of the vulnerability of the transport network in which the bridges are included taking into account the modification of the traffic flows when bridge infrastructures are damaged. The results of this pilot study can be used as a first step for a proper allocation of economic resources in the planning of seismic retrofit interventions to minimize the overall risk and manage the immediate post-earthquake emergency phase and guide rescuers in reaching the affected and critical areas.

Preserving the allocation ratio at every allocation with biased coin randomization and minimization in studies with unequal allocation

The demand for unequal allocation in clinical trials is growing. Most commonly, the unequal allocation is achieved through permuted block randomization. However, other allocation procedures might be required to better approximate the allocation ratio in small samples, reduce the selection bias in open-label studies, or balance on baseline covariates. When these allocation procedures are generalized to unequal allocation, special care is to be taken to preserve the allocation ratio at every allocation step. This paper offers a way to expand the biased coin randomization to unequal allocation that preserves the allocation ratio at every allocation. The suggested expansion works with biased coin randomization that balances only on treatment group totals and with covariate-adaptive procedures that use a random biased coin element at every allocation. Balancing properties of the allocation ratio preserving biased coin randomization and minimization are described through simulations. It is demonstrated that these procedures are asymptotically protected against the shift in the rerandomization distribution identified for some examples of minimization with 1:2 allocation. The asymptotic shift in the rerandomization distribution of the difference in treatment means for an arbitrary unequal allocation procedure is explicitly derived in the paper.

Multi-region input–output analysis of CO 2 emissions embodied in trade: The feedback effects

Energy-related CO 2 emissions embodied in international trade have been widely studied by researchers using the environmental input–output framework. Despite the increasing interest in using the multi-regional input–output (MRIO) model by researchers, few studies have looked into the mechanism of feedback effects. We introduce a method called the stepwise distribution of emissions embodied in trade (SWD-EET) to reveal how the emissions embodied in trade are absorbed by a country's final demands through a series of allocation steps. A country's indirect absorption patterns and its indirect trade balance of emissions from bilateral trade with other countries are also studied based on the proposed method. An empirical study using the data of Asian economies shows significant differences in the “consumption-based” emission estimates for some economies due to feedback effects through international trade. The differences can be largely captured by the first step or the first two steps of the adjustment procedure in the SWD-EET analysis. Other findings and some recommendations are also presented.

A stochastic neighborhood search approach for airport gate assignment problem

An appropriate and efficient gate assignment is of great importance in airports since it plays a major role in the revenue obtained from the airport operations. In this study, we have focused mainly on maximum gate employment, or in other words minimize the total duration of un-gated flights. Here, we propose a method that combines the benefits of heuristic approaches with some stochastic approach instead of using a purely probabilistic approach to top-down solution of the problem. The heuristic approaches are usually used in order to provide a fast solution of the problem and later stochastic searches are used in order to ameliorate the previous results of the heuristic approach whenever possible. The proposed method generates an assignment order for the whole planes that corresponds to assignment priority. The ordering process is followed by the allocation step. Since, in practice, each airport has its own physical architecture, there have been arisen many constraints mainly concerning airplane types and parking lots in this step. Sequentially handling the plane ordering and allocation phases provides us great modularity in handling the constraints. The effectiveness of the proposed methodology has been tried to be illustrated firstly on fictively generated flight schedule data and secondly on the real world data obtained from a real world application developed for İstanbul Atatürk Airport.

QoS aware storage cache management in multi-server environments

In this paper, we propose a novel two-step approach to the management of the storage caches to provide predictable performance in multi-server storage architectures: (1) An adaptive QoS decomposition and optimization step uses max-flow algorithm to determine the best decomposition of application-level QoS to sub-QoSs such that the application performance is optimized, and (2) A storage cache allocation step uses feedback control theory to allocate shared storage cache space such that the specified QoSs are satisfied throughout the execution.

Brick tunnel randomization for unequal allocation to two or more treatment groups

Studies with unequal allocation to two or more treatment groups often require a large block size for permuted block allocation. This could present a problem in small studies, multi-center studies, or adaptive design dose-finding studies. In this paper, an allocation procedure, which generalizes the maximal procedure by Berger, Ivanova, and Knoll to the case of K≥2 treatment groups and any allocation ratio, is offered. Brick tunnel (BT) randomization requires the allocation path drawn in the k-dimensional space to stay close to the allocation ray that corresponds to the targeted allocation ratio. Specifically, it requires the allocation path to be confined to the set of the k-dimensional unitary cubes that are pierced by the allocation ray (the 'brick tunnel'). The important property of the BT randomization is that the transition probabilities at each node within the tunnel are defined in such a way that the unconditional allocation ratio is the same for every allocation step. This property is not necessarily met by other allocation procedures that implement unequal allocation.

Understanding the allocation of attention when faced with varying perceptual load in partial report: A computational approach

The allocation of visual processing capacity is a key topic in studies and theories of visual attention. The load theory of Lavie (1995) proposes that allocation happens in two steps where processing resources are first allocated to task-relevant stimuli and secondly remaining capacity ‘spills over’ to task-irrelevant distractors. In contrast, the Theory of Visual Attention (TVA) proposed by Bundesen (1990) assumes that allocation happens in a single step where processing capacity is allocated to all stimuli, both task-relevant and task-irrelevant, in proportion to their relative attentional weight. Here we present data from two partial report experiments where we varied the number and discriminability of the task-irrelevant stimuli (Experiment 1) and perceptual load (Experiment 2). The TVA fitted the data of the two experiments well thus favoring the simple explanation with a single step of capacity allocation. We also show that the effects of varying perceptual load can only be explained by a combined effect of allocation of processing capacity as well as limits in visual working memory. Finally, we link the results to processing capacity understood at the neural level based on the neural theory of visual attention by Bundesen et al. (2005).

On the second role of the random element in minimization

Although the main reason for adding a random element at every step of minimization procedure is to reduce predictability of the upcoming treatment assignments in single-center open-label trials, there is another reason for its use, applicable to double-blind trials. Adding the random element at every allocation step allows one to avoid a fully deterministic sequence of treatment assignments for sequences of covariates for which at every allocation step one of the treatments leads to a better balance in covariates than all other treatments. An example of such a sequence is provided in this communication.

HLS-l: A High-Level Synthesis Framework for Latch-Based Architectures

Level-sensitive latches are widely used in high-performance custom designs while edge-triggered flip-flops are predominantly used in application-specific integrated circuits. We consider a latch as a basis for storage and address each step of high-level synthesis (HLS), including scheduling, allocation, and control synthesis. While the use of latches provides an opportunity to reduce the latency during the scheduling, the register allocation has to take extra conflicts caused by latch into account, and the control synthesis has to be tailored to support the latch-based data-path. Optimization potentials specific to this HLS are identified and solutions are proposed. Specifically, the register allocation can be improved by refining the operation schedule in a way to reduce the number of edges in a register conflict graph; the latency can be reduced by adjusting the clock duty cycle in a way to generate a tighter schedule. All the steps of HLS and optimization procedures were integrated into a framework called HLS-l. It was tested on benchmark designs implemented in 1.1-V, 45 nm complementary metal-oxide-semiconductor technology. Compared to the conventional HLS, HLS-l was able to reduce the latency by 18.2% on average with 9.2% less area and 16.0% less power consumption. The application of HLS-l to an industrial example is demonstrated through the design of a module extracted from H.264/advanced video coding.

Portfolio Choice Implications of Parameter and Model Uncertainty in Factor Models

This paper examines the portfolio choice implications of incorporating parameter and model uncertainty in (conditionally) linear factor models using industry portfolios. I examine a CAPM, a linear factor model with different predictor variables (dividend yield, price to book ratio, price to earnings ratio, and price to sales ratio), and a time-varying CAPM. All approaches incorporate parameter uncertainty in a mean-variance framework. I consider a time-varying CAPM with changing conditional variance. It is shown that taking into account the time variation in market betas improves the portfolio performance as measured by the ex-post Sharpe ratio compared to both an unconditional CAPM and a linear factor model with predictor variables. I also show the implications of using a Black-Litterman framework versus using a standard mean-variance approach in the asset allocation step. Black-Litterman framework can be thought as a model averaging approach and thus helps deal with both the parameter and model uncertainty problems. I show that Black-Litterman approach results in portfolios with a higher Sharpe ratio than those obtained by a standard mean-variance framework using a single model or historical averages.

Buffer and Register Allocation for Memory Space Optimization

In today's embedded systems, memory hierarchy is rapidly becoming a major factor in terms of power, performance and area. This is especially true for embedded multimedia applications using temporary multi-dimensional arrays that are typically used to store intermediate results during multimedia processing. In this paper, we propose a new technique that optimizes the use of the cache and the registers. It consists in combining buffer and register allocation to reduce the size of the temporary arrays. Firstly we use the concept of live data to replace each array by a buffer of lower size. Then we replace references to these buffers by registers. The buffer allocation step keeps only useful data in memory and the register allocation step allows taking advantage of data reuse in internal loops. Codes considered in this paper are multimedia applications structured as a sequence of loop nests. The experiments are made on Unix environment and on the StepNP simulator (MPSoC platform of STMicroelctronics). They show that our technique yields significant reduction of the number of data cache and TLB misses.

An Aumann-Shapley Value Based Congestion Cost Allocating Method In Bilateral Transaction Environment

In bilateral transaction market, the congestion relief cost should be allocated in an equitable manner among all the market participants contributing to the congestion. Unfortunately in the allocation of the congestion relief cost to the congested lines, which is the first step of cost allocation, the previously proposed shadow price method and the aggregated allocation method both have some shortcomings. To overcome these shortcomings, a cost allocation method based on the Aumann-Shapley value is proposed. By means of the Aumann-Shapley value, a solution concept in the cooperative game with infinitely many players, the proposed method takes all orders of relieving congestion on the lines into consideration and satisfies the consistency of the allocation, thus guarantees equitable allocation of the congestion relief cost to the congested lines. In addition, the calculating procedure is both simple and accurate due to the use of the Gauss Integration method. Test results show that this method can lead to better allocation than do the shadow price method and the aggregated allocation method.

Routing of 40-gb/s streams in wavelength-routed heterogeneous optical networks

In this paper, we address the design and management issues in routing a mixture of OC-192 and OC-768 streams in wavelength-routed optical networks. We assume that fiber links in the network are heterogeneous with respect to their transmission capability (i.e., links are designed to handle a given maximum bit-rate imposed by regenerator spacing). We investigate the issues of routing connection demands of various bit-rate requirements in such heterogeneous networks. In this environment, we introduce the routing of multirate traffic (RMT) problem. The RMT problem is informally defined as the process of finding the best routing which maximizes the total bandwidth carried in the network, for a set of sessions, within a given TDM equipment budget. We propose a two-phase optimization scheme (two-phase RMT). This scheme first obtains a basis solution used in routing 40-Gb/s traffic only on OC-768 capable links without the use of TDM equipment. In the second phase, an iterative routing, rerouting, and resource allocation step is used to optimize the total bandwidth carried in the network, while allowing 40-Gb/s traffic to be routed on OC-768 incapable links by the proper installation of TDM multiplexors and demultiplexers at some strategic locations in the network. Numerical results reveal the following: 1) the two-phase RMT optimization algorithm provides substantial savings in terms of both the total TDM equipment installed and number of wavelengths used; 2) noticeable enhancements of the bandwidth utilization and the TDM budget are observed when the route-optimization takes into account the transmission quality of the links; and 3) the use of intermediate TDM multiplexing/demultiplexing functions provides substantial savings, in terms of the total number of channels, over the source-splitting scheme.

분산 객체지향 데이타베이스에서 분산 설계 및 구현

This paper addresses the design and implementation of class distribution in distributed object-oriented databases. The proposed strategy of distribution consists of two-step design of fragments. One is class fragmentation and the other is allocation of fragments. In step of class fragmentation, we have defined partitioning algorithms to reflect the characteristics of object-oriented databases such as method, inheritance and composite-object. In step of allocation, we have defined the objective function for allocation considering system operating cost including storage, query processing and communication and implemented it using Genetic Algorithm.

Economic allocation: Examples and derived decision tree

Goal, Scope and BackgroundIn the recently published (Dutch) Handbook on LCA, economic allocation is advised as baseline method for most allocation situations in a detailed LCA. Although the Handbook on LCA aimed to provide a ‘cookbook’ with operational guidelines for conducting each step of an LCA, this was not completely achieved for the allocation step. The guidelines for allocation largely remained at the level of principles. This restricted elaboration of economic allocation may hamper application in practice. Therefore, this paper elaborates some examples applying economic allocation.MethodTwo concepts are of particular importance when applying economic allocation: functional flow and multi-functional process. The definitions of these concepts are presented and discussed. The basic principle of economic allocation is that having determined the various functional flows of a multi-functional process, all other flows need to be allocated to these functional flows according to their shares in the total proceeds. Proceeds are based on prices and these are not always easy to determine for a process. A summary of possible solutions for different problems when determining prices is given.Results and DiscussionThe examples presented focus on co-production and various recycling situations. All examples are hypothetical in order to avoid discussions on the data. The examples show that the prices of the functional flows determine the allocation results. It is of importance to have correct information on the relative prices of the functional flows at stake, especially whether they are negative or positive. Learning from these examples, we establish a decision tree for economic allocation. The decision tree is meant for identifying and handling multi-functionality situations starting from a defined (product) system. This decision tree is with minor adaptations also applicable to other allocation methods and has a more general value than for the economic allocation method only.Conclusions and perspectiveThe examples have helped us to establish a decision tree for handling the multi-functionality problem by economic allocation. The examples can be broadened to other materials and allocation situations. We would encourage others to provide other examples and experiences as we expect that these will help to further improve and refine the guidelines and decision tree for economic allocation in future.

Activity-based costing: a practical model for cost calculation in radiotherapy

Purpose The activity-based costing method was used to compute radiotherapy costs. This report describes the model developed, the calculated costs, and possible applications for the Leuven radiotherapy department. Methods and materials Activity-based costing is an advanced cost calculation technique that allocates resource costs to products based on activity consumption. In the Leuven model, a complex allocation principle with a large diversity of cost drivers was avoided by introducing an extra allocation step between activity groups and activities. A straightforward principle of time consumption, weighed by some factors of treatment complexity, was used. The model was developed in an iterative way, progressively defining the constituting components (costs, activities, products, and cost drivers). Results Radiotherapy costs are predominantly determined by personnel and equipment cost. Treatment-related activities consume the greatest proportion of the resource costs, with treatment delivery the most important component. This translates into products that have a prolonged total or daily treatment time being the most costly. The model was also used to illustrate the impact of changes in resource costs and in practice patterns. Conclusion The presented activity-based costing model is a practical tool to evaluate the actual cost structure of a radiotherapy department and to evaluate possible resource or practice changes.

From dynamic IP transport service ordering to DiffServ network configuration

The Internet Engineering Task Force (IETF) proposes the Differentiated Services (DiffServ) architecture [IETF Request for Comments 2475, 1998] as a basic mechanism for providing QoS in the Internet. However, this is not enough. For a complete QoS solution, network and service management for DiffServ networks needs to be defined. In this paper, we describe the design, implementation, and evaluation of a QoS management system. The system allows a customer to dynamically order a guaranteed IP transport service from an Internet Service Provider over a Web-interface. The system then performs all the mappings and resource allocation steps needed. Finally, it configures IP DiffServ routers such that they provide the requested service. All levels and steps in the process are under policy-control, which allows for very flexible operation of the system. The system has been tested on a small lab internal test network. Finally, lessons learnt during the implementation and tests together with issues and problem with our approach on QoS management are described.

An optimal allocation of carry-save-adders in arithmetic circuits

Carry-save-adder (CSA) is one of the most widely used components for fast arithmetic in industry. This paper provides a solution to the problem of finding an optimal-timing allocation of CSAs in arithmetic circuits. Namely, we present a polynomial time algorithm which finds an optimal-timing CSA allocation for a given arithmetic expression. We then extend our result for CSA allocation to the problem of optimizing arithmetic expressions across the boundary of design hierarchy by introducing a new concept, called auxiliary ports. Our algorithm can be used to carry out the CSA allocation step optimally and automatically and this can be done within the context of a standard RTL synthesis environment.

Cell lineage determination in the mouse.

During the peri-implantation development of the mouse embryo from the blastocyst through gastrulation, Pou5f1 (OCT-4) down-regulation is closely linked to the initial step of lineage allocation to extraembryonic and embryonic somatic tissues. Subsequently, differentiation of the lineage precursors is subject to inductive tissue interactions and intercellular signalling that regulate cell proliferation and the acquisition of lineage-specific morphological and molecular characteristics. A notable variation of this process of lineage specification is the persistence of Pou5f1 activity throughout the differentiation of the primordial germ cells, which may underpin their ability to produce pluripotent progeny either as stem cells (embryonic germ cells) in vitro or as gametes in vivo. Nevertheless, intercellular signalling still plays a critical role in the specification of the primordial germ cells. The findings that primordial germ cells can be induced from any epiblast cells and that they share common progenitors with other somatic cells provide compelling evidence for the absence of a pre-determined germ line in the mouse embryo.

Parallel Implementation of a Class of Adaptive Signal Processing Applications

Recently, High Performance Computing (HPC) platforms have been employed to realize many computationally demanding applications in signal and image processing. These applications require real-time performance constraints to be met. These constraints include latency as well as throughput. In order to meet these performance requirements, efficient parallel algorithms are needed. These algorithms must be engineered to exploit the computational characteristics of such applications. In this paper we present a methodology for mapping a class of adaptive signal processing applications onto HPC platforms such that the throughput performance is optimized. We first define a new task model using the salient computational characteristics of a class of adaptive signal processing applications. Based on this task model, we propose a new execution model. In the earlier linear pipelined execution model, the task mapping choices were restricted. The new model permits flexible task mapping choices, leading to improved throughput performance compared with the previous model. Using the new model, a three-step task mapping methodology is developed. It consists of (1) a data remapping step, (2) a coarse resource allocation step, and (3) a fine performance tuning step. The methodology is demonstrated by designing parallel algorithms for modern radar and sonar signal processing applications. These are implemented on IBM SP2 and Cray T3E, state-of-the-art HPC platforms, to show the effectiveness of our approach. Experimental results show significant performance improvement over those obtained by previous approaches. Our code is written using C and the Message Passing Interface (MPI). Thus, it is portable across various HPC platforms.