Computer Verification Research Articles

Computer verification of fluence map for intensity modulated radiation therapy.

In a treatment planning system for intensity modulated radiation therapy (IMRT), the time sequence of multileaf collimator (MLC) settings are derived from an optimal fluence map as a postoptimization process using a software module called a "leaf sequencer." The dosimetric accuracy of the dynamic delivery depends on the functionality of the module and it is important to verify independently the correctness of the leaf sequences for each field of a patient treatment. This verification is unique to the IMRT treatment and has been done using radiographic film, electronic portal imaging device (EPID) or electronic imaging system (BIS). The measurement tests both the leaf sequencer and the dynamic multileaf collimator (MLC) delivery system, providing a reliable assurance of clinical IMRT treatment. However, this process is labor intensive and time consuming. In this paper, we propose to separate quality assurance (QA) of the leaf sequencer from the dynamic MLC delivery system. We describe a simple computer algorithm for the verification of the leaf sequences. The software reads in the leaf sequences and simulates the motion of the MLC leaves. The generated fluence map is then compared quantitatively with the reference map from the treatment planning system. A set of pre-defined QA indices is introduced to measure the "closeness" between the computed and the reference maps. The approach has been used to validate the CORVUS (NOMOS Co., Sewickley, PA) treatment plans. The results indicate that the proposed approach is robust and suitable to support the complex IMRT QA process.

Computer verification of the Ankeny--Artin--Chowla Conjecture for all primes less than $100000000000$

Let p be a prime congruent to 1 modulo 4, and let t, u be rational integers such that (t + u∨p)/2 is the fundamental unit of the real quadratic field Q(∨p). The Ankeny-Artin-Chowla conjecture (AAC conjecture) asserts that p will not divide u. This is equivalent to the assertion that p will not divide B (p-1)/2 , where B n denotes the nth Bernoulli number. Although first published in 1952, this conjecture still remains unproved today. Indeed, it appears to be most difficult to prove. Even testing the conjecture can be quite challenging because of the size of the numbers t, u; for example, when p = 40094470441, then both t and u exceed 10 330 000 . In 1988 the AAC conjecture was verified by computer for all p < 10 9 . In this paper we describe a new technique for testing the AAC conjecture and we provide some results of a computer run of the method for all primes p up to 10 11 .

Control strategies analysis for a batch distillation column with experimental testing

The dynamic nature and the non-linear behaviour of batch distillation equipment pose challenging control system design when products of constant purity are to be recovered. Several alternative column configurations and operating policies have been studied. However, issues related to the on-line operation of such process have not been properly addressed. The present work describes the investigation with experimental verification of computer based control strategies to batch distillation: a programmable adaptive controller (PAC), a self-tuning regulator (STR) and a non-linear model predictive control (MPC). The developed control systems made the conventional batch distillation column more efficient and easy to operate. Experiments performed on the pilot column confirm the simulation results.

Kinetics of radiation-induced grafting of 2-hydroxyethyl methacrylate onto chloroprene rubber membrane and computer verification

Kinetics of radiation-induced grafting of 2-hydroxyethyl methacrylate onto chloroprene rubber membrane and computer verification

Kinetics of radiation‐induced grafting of 2‐hydroxyethyl methacrylate onto chloroprene rubber membrane and computer verification

Grafting of 2-hydroxyethyl methacrylate(HEMA) onto chloroprene rubber(CR) membrane was carried out in ethanol by direct cobalt-60 gamma ray irradiation. The kinetics of the grafting reaction was studied in respect of concentration of monomer, dose rate and temperature. The experimental results show that the functional relationship equation is dg0/dt = k[M]1.5 Ḋ. The apparent activation energy and collision frequency factor of the grafting polymerization are 46.2 kJ mol−1 and 4.98 × 107 mg cm−2 kGy−1 mol−1.5 litre1.5, respectively. The work established the relationship of the initial grafting rate (dg0/dt) with various effect factors: ln (dg0 dt) = 17.7 − 5560(1/T) + 1.5 ln [M] + ln Ḋ. This equation is also verified for the first time by a software named SMR, which function is using multiple linear regression to calculate the regression coefficient of a linear equation. © 1999 Society of Chemical Industry

Matrix representation of complex vacuum device configuration with a view to computer simulation

It is a well known fact that the slow convergence of the Monte-Carlo method precludes it's use for the accurate evaluation of the performance of a complex vacuum device. The noticeable truncation of each turn of the cyclic simulation process is able to lessen the difficulties. A computation using the topological matrixes can speed this up. It may also be efficient in the protection from faulty input data by means of computer verification.

A multiresolution approach to computer verification of handwritten signatures

We took a multi-resolution approach to the signature verification problem. The top-level representation of signatures was the global geometric features. A multi-resolution representation of signatures was obtained using the wavelet transformation. We built VQ and network classifiers to demonstrate the advantages of the multi-resolution approach. High verification rates were achieved based on a limited database.

Phase Portraits of Planar Vector Fields: Computer Proofs

We present an algorithm for computer verification of the global structure of structurally stable planar vector fields. Constructing analytical proofs for the qualitative properties of phase portraits has been difficult. We try to avoid this barrier by augmenting numerical computations of trajectories of dynamical systems with error estimates that yield rigorous proofs. Our approach lends itself to high-precision estimates, because the proofs are broken into independent calculations whose length in f1oatingpoint operations does not increase with increasing precision. The algorithm is tested on a system that arises in the study of Hopf bifurcation of periodic orbits with 1:4 resonance.

A simple verification method for the Goldbach conjecture

In class, students are often curious about the fact that any even integer bigger than 4 is the sum of two prime numbers. They usually cannot understand why the obvious fact cannot be proved mathematically. From the computational point of view, unless we find an even number which cannot be expressed as a sum of two prime numbers, we cannot claim the Goldbach conjecture is true. So, the most important thing is to try all the even integers to check if they conform to the Goldbach conjecture. Unfortunately, most of the modern verification methods need deep mathematical ideas which usually cannot be understood by undergraduate students. In this paper, we present a simple but elegant computer verification method for the Goldbach conjecture, and propose two implementation approaches (via C and Maple) to this method. Compared with other verification methods, ours is easy to implement and easy to understand. But of course, at present we may not expect this method, or probably any other existing methods, to be able...

A simple hand verification of the Bieberbach conjecture for 2 ≦ n ≦ 7

In comparison with the de Branges-Gautschi computer verification of the Bieberbach conjecture for 2 ≦ n ≦ 30, we give a simple hand verification of this conjecture at least for the first values of n, namely for 2 ≦ n ≦ 7, etc.

Towards verification of computer codes for the performance assessment of radioactive waste disposal

Abstract Performance assessment of radioactive waste disposal, to a considerable extent, has to rely on results obtained with computer codes which in turn are based on mathematical models of the disposal system. It is therefore crucial for the credibility of long-term safety analysis to establish a defensible basis for confidence in the capabilities of performance assessment codes. As preparation for a discussion of related activities, the main features of a disposal system, common characteristics of performance assessment codes, and a taxonomy of verification techniques are summarized. The article focuses on steps towards verification of performance assessment codes, and particularly elaborates the related achievements of recent international code intercomparisons. It is concluded that intercomparison exercises make substantial contributions towards verification of participating codes, but must not be considered as verification by themselves.

Fluences and spectra of accelerator generated fast neutrons

A fast neutron irradiation station has been designed at the University of Massachusetts at Lowell. The fluence delivered by this station is less than that of a nuclear reactor, but it is essentially free of slow neutrons and the admixture of gamma rays is small. The station, dosimetry methods, a computer code, verification techniques, and applications are described. The information provided should enable others to construct a similar station on type CN or tandem accelerators.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Modelling of the Secondary Clarifier Combined with the Activated Sludge Model No. 1

Modelling of activated sludge wastewater treatment plants is today generally based on the Activated Sludge Model No. 1 combined with a very simple model for the secondary settler. This paper describes the development of a model for the secondary clarifier based on the general flux theory for zone settling, which can be used in combination with the Activated Sludge Model to form a dynamic computer model/program for a wastewater treatment plant. In addition to the flux model, the developed model includes a simple model for predicting the contents of paniculate components in the effluent This latter model is a purely empirical model, which connects the effluent quality with the hydraulic load, suspended solids load and the nitrate load. The paper describes the model and gives some basic examples on computer simulations and verification of the model.

Computer verification of human users' identity: A theoretical model and some evaluation criteria

There is today a great need for reliable methods to securely verify a human computer user. Passwords are no longer sufficient in many applications. For a sound choice of an identity verification method one must be able to objectively compare the candidates. This can be accomplished only with a general description of the process which is valid for all methods and with a common way of measuring performance. This paper presents a general model of what actually happens in equipment for identity verification. It also gives criteria for good descriptions of the reliability of the equipment in terms of the possibility of a false decision.

Programmable fractional sample delay filter with Lagrange interpolation

A new linear time-invariant FIR filter which can be programmed to synthetise any fractional sample delay with Lagrange interpolation is presented. An analytic closed-form expression for the coefficients of such an FIR filter is derived. Computer verification is provided for the N = 4 case.

Verification of computer fabricated compensating filters

Verification of computer fabricated compensating filters

Phenomenological studies on molten core-concrete interactions

Recent assessments of risk due to severe accidents in light water reactors indicate that molten core-concrete interactions (MCCI) may dominate containment loads and performance, as well as the release of non-volatile fission product aerosols to the containment building. This program has investigated several important aspects of MCCIs in an effort to support the USNRC integral melt-concrete programs as well as the CORCON and VANESA computer code development and verification program. Among these are interlayer heat and mass transfer and liquid-liquid boiling processes. The issues of interlayer heat and mass transfer address phenomena that occur primarily interior to the molten core debris itself. Models have been developed to predict the onset of entrainment between liquid layers, the rate of entrainment, and the rate of heat transfer, both with and without entrainment. Application to the reactor case indicates that entrainment and mixing may or may not occur, depending upon the prevailing thermal hydraulic conditions in the melt. The issues of liquid-liquid film boiling address phenomena that occur primarily at the melt-coolant interface. Results from melt-water film boiling studies have suggested that the coolant heat flux increases above the flat plate limit with non-condensable gas injection from below. Steam explosions occur frequently; the frequency and magnitude vary with gas injection rate.

A note on statistical sensitivity computation in switched-capacitor networks

The sensitivity of switched-capacitor (SC) networks to the ratios of capacitances is considered. A special form of the modified Tellegen's theory is proposed and used to formulate simple closed-form matrix equation for the multiparameter sensitivity calculation. The results of a computer verification of the proposed sensitivity computation method on both a low-pass fifth order and a bandpass sixth-order elliptic filter agree well with results obtained using the Monte Carlo method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A computer verification of a pretty mathematical result

A very appropriate use of a computer in a mathematics class is to provide investigation vehicles for formulating conjectures to be verified theoretically. In other words, first we notice something and then we try to prove it. In this paper we shall reverse the process, first arguing the plausibility of a very fascinating result and then obtaining confirmation by looking at some computer generated data. The argument is based on the work of the eighteenth century mathematical giant, Leonhard Euler (1707-1783).

Method of pattern positioning for automatic verification of seal imprint

AbstractIn automatic computer verification of seal imprints accurate positioning of an examined seal imprint over a registered imprint is of great importance. This paper proposes a method which positions an examined seal imprint in relation to a parallel shift and rotation by using the centroid of its frame figure and the pixels on a circle of a certain radius from the centroid. Since this method achieves positioning by using local features of the examined seal imprint, rapid positioning is possible. In the presence of small defects in the imprint frame this method has the advantage that the centroid of the seal imprint is accurately obtained and is not affected by distortion of the imprint frame. In a positioning experiment based on this method 240 actual seal imprints were used. All imprints were positioned within a ±0.1‐mm parallel shift error and more than 99% of the seal imprints were positioned within ±1.76° rotation angle errors. A verification experiment was conducted using a seal imprint verification system which incorporated the principles of this method. As a result, the verification error which was caused by the positioning error was found to be 0.83%. The experimental results show that the proposed positioning method is efficient for automatic verification of seal imprints.