Auxiliary Store Research Articles

Tactical supply chain planning supported on a grasp/MIP heuristic

The current work develops a MIP model for the planning of shipping and disembarking operations in a distribution centre that receives products from a production plant, auxiliary stores and foreign suppliers. The objective is to minimise the costs of the logistic chain. The constraints affecting the operation of the distribution centre are product storage capacity and product handling in cargo reception and unloading docks. Then, a sensitivity analysis is conducted to determine the incidence of key parameters on the operation costs of the system and to identify efficient operation conditions. Finally, a statistical analysis of the solution procedure as applied to the problem allows assessing not only small scale gap and CPU times, but also medium and large scale CPU times.

TACTICAL SUPPLY CHAIN PLANNING SUPPORTED IN A GRASP/MIP HEURISTIC

The current work develops a MIP model for the planning of shipping and disembarking operations in a distribution centre that receives products from a production plant, auxiliary stores and foreign suppliers. The objective is to minimise the costs of the logistic chain. The constraints affecting the operation of the distribution centre are product storage capacity and product handling in cargo reception and unloading docks. Then, a sensitivity analysis is conducted to determine the incidence of key parameters on the operation costs of the system and to identify efficient operation conditions. Finally, a statistical analysis of the solution procedure as applied to the problem allows assessing not only small scale gap and CPU times, but also medium and large scale CPU times.

Implementation of the ATLAS Run 2 event data model

During the 2013-2014 shutdown of the Large Hadron Collider, ATLAS switched to a new event data model for analysis, called the xAOD. A key feature of this model is the separation of the object data from the objects themselves (the ‘auxiliary store’). Rather than being stored as member variables of the analysis classes, all object data are stored separately, as vectors of simple values. Thus, the data are stored in a ‘structure of arrays’ format, while the user still can access it as an ‘array of structures’. This organization allows for on-demand partial reading of objects, the selective removal of object properties, and the addition of arbitrary user- defined properties in a uniform manner. It also improves performance by increasing the locality of memory references in typical analysis code. The resulting data structures can be written to ROOT files with data properties represented as simple ROOT tree branches. This paper focuses on the design and implementation of the auxiliary store and its interaction with ROOT.

Bidirectional data flow analysis for type inferencing

Tennenbaum's data flow analysis based formulation of type inferencing is termed bidirectional in the “Dragon Book”; however, it fails to qualify as a formal data flow framework and is not amenable to complexity analysis. Further, the types discovered are imprecise. Here, we define a formal data flow framework (based on bidirectional data flow analysis) which discovers more precise type information and is amenable to complexity analysis. We compare data flow analyses with the more general constraint-based analyses and observe that data flow analyses represent program analyses without unbounded auxiliary store. We show that if unlimited auxiliary store is allowed then no data flow analysis would need more than two passes; if auxiliary store is disallowed then type inferencing requires bidirectional data flow analysis.

A general transposition method for a matrix on auxiliary store

An algorithm is developed and described for transposing a matrix larger than available working storage. If an (n×m)-matrix is stored in row-major order, and blocks ofn elements may be transferred to and from working storage at a time, the algorithm needsw=(5[m/n]+8)·n elements to be present in working storage at a time and requires [log2(2mn/w)] passages over the matrix. The algorithm is as efficient as earlier methods but needs no extra backing storage space. An algebra for mixed radix notation and a generalization of mixed radix notation is introduced for the description and verification of transposition algorithms, and earlier algorithms are briefly certified or disproved.

On the optimization of performance of time-sharing systems by simulation

A simulation model of a time-sharing system with a finite noncontiguous store and an infinite auxiliary store is used to study the variation of system parameters such as store size, number of jobs allowed to execute simultaneously, job-scheduling algorithm, etc. The effects of these variations on a measure of system performance is used to ascertain which of the parameters controllable by the job-scheduling algorithm, including the scheduling itself, require optimization, and which of the parameters not normally controllable by the scheduling algorithm have a marked effect on system performance. System performance is based upon the mean cost of delay to all jobs processed. It is shown that significant improvements in the measure of system performance can be obtained by using variable time-slice techniques and by selecting the optimum round-robin cycle time. It appears that these features would benefit from optimization whereas other parameters controllable by the scheduling algorithm affect system performance in a predictable manner and would not benefit from optimization. Features not normally under the control of the scheduling algorithm can also have a marked effect on the measure of performance; in particular, supervisor overheads, the size of the store, and the speed of the CPU. A comparison is made between the results of the simulation model and two analytical equations for quantum-oriented nonpreemptive time-sharing systems. The comparison is found to be very favorable.

RESOURCES NEEDED FOR CAI

Abstract: CAI resources for R and D are discussed under these headings: hardware, software, personnel, funding and facilities. Functions of the central processor, auxiliary stores and input‐output units are considered. The computer program or operating system and the assembler and its author‐entry language are next discussed. CAI implications for curriculum are introduced with reference to “dry” versus “wet” laboratory work, the Sumerian game and the computer's capacity for information retrieval. Personnel needs flowing from the disparate skills involved in CAI and the costs of a modest R and D system are outlined.

The determination of eigenvalues and eigenfunctions of a linear integral operator with a symmetrical kernel by means of group elimination of unknowns

SYSTEMS of equations of a high order often arise during the determination of the eigenvalues and eigenfunctions of a linear integral operator by the method of reducing it to a system of linear algebraic equations. This is because in order to obtain a sufficiently accurate solution it is necessary to take a sufficiently accurate quadrature formula with a large number of nodes. The limited size of the working store of a high-speed computer does not allow placing matrices of high orders in it and a slow auxiliary store is needed. Under these conditions it is natural to use a method of group treatment of the unknowns in which a matrix of a high order is partitioned into block matrices of a smaller order, whereby an algebraic problem of a high order can be reduced to a problem of a lower order. For this purpose a method was proposed in [1] for the block elimination of unknowns. To apply this successfully the unknowns must be so chosen that a part of them, corresponding to “rough” approximation of the problem is the main part in a more accurate approximation. The applications of this method to the problem of determining the eigenvalues and eigenfunctions of a linear integral operator with a continuous symmetrical kernel are considered in this paper. The high order matrices arising during the solution of this problem have the property that the blocks bordering the upper left corner of such a matrix are small.

A transistor digital computer with a magnetic-drum store

The paper describes the design of a transistor digital computer, the full-scale machine and its prototype. The general arrangement of the two machines is similar, and both employ a magnetic drum for the main and auxiliary stores. The latter are provided by regenerative tracks or revolvers which have reading and writing heads spaced by a distance equivalent to one, two or eight word periods. The output of the reading amplifier is connected via a gate to the writing amplifier, and the track operates as a delay-line type of store. Point-contact transistors are used principally as pulse amplifiers, staticizors and for waveform generation. In the pulse amplifier the transistor operates as a 2-state circuit-it is turned on by a digit pulse and reset at the end of each digit period by a regular clock waveform with a pulse repetition frequency of 125 kc/s. Point-contact diodes are used to perform the logical operations and for gating. Two-state circuits employing single transistors are also used for the staticizors and for the waveform generation units. A pseudo 2-address code is used in both machines; both the address operand and the address of the next instruction are specified in each instruction, to permit reduction in the access time by optimum coding. The full-scale machine has an 8-word B-register which may also be used as a rapid-access number store and an automatic multiplier.