Showing papers by "Worcester Polytechnic Institute published in 1983"
TL;DR: In this article, a constant volume, constant pressure system was employed to measure the adsorption isotherms and diffusion coefficients of C6 (hexane, cyclohexane and benzene) and C8 (p-xylene, m-exylene, o -xylene and ethylbenzene) hydrocarbons in silicalite in the temperature range of 20°-200°C.
161 citations
TL;DR: In this article, a combined observability/measurement placement algorithm that both tests the measured network for observability and evaluates pseudo measurement sites as to the desirability of their inclusion into the measurement set is presented.
Abstract: Measurement system failures and modeling constraints may make it impossible for the power system state estimator to estimate bus voltage magnitudes and angles at every bus in the power system from the available real-time measurements. Such a measurement deficiency may be remedied by adding pseudo measurements of estimated bus loads. This paper presents a combined observability/measurement placement algorithm that both tests the measured network for observability and evaluates pseudo measurement sites as to the desirability of their inclusion into the measurement set.
153 citations
TL;DR: A new implementation of the Wiener restoration filter that uses as its optimality criterion the minimization of the mean-square error between the undistorted image of the object and the filtered image to improve the quality of digital nuclear medicine images.
Abstract: To improve the quality of digital nuclear medicine images, we have developed a new implementation of the Wiener restoration filter The Wiener filter uses as its optimality criterion the minimization of the mean‐square error between the undistorted image of the object and the filtered image In order to form this filter, the object and noise power spectrums are needed The noise power spectrum for the count‐dependent Poisson noise of nuclear medicine images is shown to have a constant average magnitude equal to the total count in the image The object power spectrum is taken to be the image power spectrum minus the total count, except in the noise dominated region of the image power spectrum where a least‐squares‐fitted exponential is used Processing time is kept to a clinically acceptable time frame through use of an array processor Pronounced noise suppression and detail enhancement are noted with use of this filter with clinical images
105 citations
TL;DR: In this article, the authors present an analysis of the sources of ill-conditioning in the power system state estimation problem and offer an alternative solution method, due to Peters and Wilkinson, that overcomes this illconditioning without losing matrix sparsity.
Abstract: Power system state estimation is usually formulated as a weighted least-squares problem and solved iteratively by the normal equations method. The normal equations solution method is well-known to exhibit a tendency to be numerically unstable on some networks. A manifestation of this numerical instability is an ill-conditioned set of linear equations that are to be solved at each iterative step. Recent papers have presented orthogonal factorization methods as remedies for this instability. Experience shows, however, that these methods tend to suffer from excessive fill-in when confronted with networks that have a high measurement redundancy. The folklore of power-system state estimation says that large numbers of bus injection measurements (as opposed to line flow measurements) tend to aggrevate the instability, no explanation for this observation, however, has appeared in the literature. This paper presents an analysis of the sources of ill-conditioning in the power system state estimation problem and offers an alternative solution method, due to Peters and Wilkinson, that overcomes this ill-conditioning without losing matrix sparsity.
95 citations
TL;DR: The crystallization and crystal growth of zeolite TPA-ZSM-5 when ammonium cation was used instead of alkali metal cations is reported in this paper.
85 citations
TL;DR: In this article, an efficient optimal design algorithm for minimizing the vibratory response of a multi-degree of freedom system under sinusoidal loading over several excitation frequencies is presented.
70 citations
TL;DR: The synthesis of zeolite TPA-ZSM-5 with (NH 4 ) 2 O/Al 2 O 3 = 38 and different amounts of Li 2 O, Na 2 O or K 2 O was studied in this article.
53 citations
TL;DR: In this paper, the effects of various additives and other modifications of the starting composition to promote the growth of larger crystals of ZSM-5 in this system were investigated and it was found that partial to complete substitution of sodium salts for sodium hydroxide had a pronounced effect on resulting morphology, yielding crystals up to 80μm, both in a narrow to a wide range of size distribution.
44 citations
TL;DR: In this paper, the incubation period preceding rollover within a stratified LNG tank involves intensive heat and mass transfers between layers, and numerical integration of equations describing these processes leads to predicted time-history and boil-off characteristics which are in excellent agreement with Sarsten's (1972) documentation of the LaSpezia rollover incident.
Abstract: The incubation period preceding ''rollover'' within a stratified LNG tank involves intensive heat and mass transfers between layers. Numerical integration of equations describing these processes leads to predicted time-history and boil-off characteristics which are in excellent agreement with Sarsten's (1972) documentation of the LaSpezia rollover incident.
40 citations
TL;DR: In this paper, the nuclear reaction was used to determine 3He depth profiles in high-energy-rate-forged Type 304L and Type 21-6-9 stainless steels following exposure to tritium.
Abstract: The nuclear reaction3He (d, p)4He was used to determine3He depth profiles in high-energy-rate-forged Type 304L and Type 21-6-9 stainless steels following exposure to tritium. A sensitivity to3He better than 1 atomic ppm and a depth resolution of about 0.5 μm were achieved. The3He decay product provides an essentially immobile trace of the diffusing tritium, and as a result tritium diffusivity and solubility may be calculated from the measured3He distribution. Tritium exposure in these experiments occurred at 343 K under 45 MPa partial pressure. The diffusion coefficient obtained at 343 K was (1.6 ± 0.3) × 10−9 mm2 per second in both steels, while the solubility at 45 MPa partial pressure was 3700 ± 900 atomic ppm for Type 304L and 7500 ± 1900 atomic ppm for Type 21-6-9.
40 citations
TL;DR: In this paper, the first synthesis of endmembers Na- and K-clinoptilolite was reported, in a temperature range 120-200 °C at autogenous pressure.
Abstract: We report here the first synthesis of endmembers Na- and K-clinoptilolite. Na, K-clinoptilolites, formed principally in nature by the alteration of siliceous volcanic ash and tuffs deposited in the ocean or in continental saline, alkaline lakes, are the most abundant zeolites occurring as minerals. However, it has been found difficult to delineate in the laboratory the conditions which lead to the crystallization of these minerals at low-temperature and low-pressure conditions. In the reactant systems studied and in a temperature range 120–200 °C at autogenous pressure, Na-clinoptilolite crystallized with the addition of a small amount (1%) of seed crystals, and K-clinoptilolite was synthesized with or without seed. Intermediate Na, K-clinoptilolites also crystallized in the seeded and unseeded systems. Coexisting phases, depending on the reactant composition, included mordenite, phillipsite, gismondine (zeolite P1) and K-feldspar. An experimental basis has now been established to determine the kinetics and paragenesis of this zeolite occurring in very large amounts in ocean and continental sediments.
TL;DR: The data indicate that the newly described method, similar to methods using EDTA for cell dislodgement, yielded relatively intact monocytes but unlike the latter method with better preserved cell spreading, can be considered for standardization to obtain pure monocyte populations from peripheral blood.
TL;DR: In this article, the first ring-chlorinated pyrimidines were synthesized from 6-trifluoromethylpyrimidine by using hydrogen chloride in phosphorus oxychloride in 72% yield.
TL;DR: In this article, the magnetic form factor has been measured for momentum transfer between 0.7 and 11 with improved precision over previous measurements, and the charge radius was determined to be 1.03 fm.
Abstract: The $^{3}\mathrm{He}$ magnetic form factor has been measured for momentum transfers between 0.7 and 11 ${\mathrm{fm}}^{\ensuremath{-}2}$ with improved precision over previous measurements. The charge form factor has been measured for momentum transfers less than 1 ${\mathrm{fm}}^{\ensuremath{-}2}$. The charge radius was determined to be 1.935\ifmmode\pm\else\textpm\fi{}0.03 fm, and the magnetic radius 1.935\ifmmode\pm\else\textpm\fi{}0.04 fm. Comparisons are made with calculations which include meson exchange corrections and reasonable agreement is found.NUCLEAR REACTIONS $d(e, {e}^{\ensuremath{'}})d$, ${q}^{2}=0.7 \mathrm{to} 11$ ${\mathrm{fm}}^{\ensuremath{-}2}$, $\ensuremath{\theta}=160\ifmmode^\circ\else\textdegree\fi{}$, measured magnetic form factor; ${q}^{2}l1$ ${\mathrm{fm}}^{\ensuremath{-}2}$, $\ensuremath{\theta}=60\ifmmode^\circ\else\textdegree\fi{}$, measured charge radius.
TL;DR: The optimality criterion technique transplanted by Khan and his coworkers into mechanism design and the kinematical refinement technique proposed by the authors are combined into a novel procedure of optimum design of flexible mechanisms.
Abstract: In this paper the optimality criterion technique transplanted by Khan and his coworkers into mechanism design and the kinematical refinement technique proposed by the authors are combined into a novel procedure of optimum design of flexible mechanisms. Cross-sectional parameters are taken as the first group of design variables; a fully-stressed mechanism is obtained by using previous researchers’ recursion formulas which contain some improvements introduced by the authors. Geometrical parameters are used as the second group of design variables; a mechanism with improved criterion of kinematic performance is obtained by means of the kinematic refinement technique. The method presented is effective and steady. An example problem in the design of a four-bar path-generating mechanism is given to illustrate the procedure.
TL;DR: In 1743, Davenport and his followers gathered around a bonfire and cast into it a veritable library of Puritan classics, including works by such celebrated divines as Matthew Henry, Richard Sibbes, Increase Mather, and Benjamin Colman.
Abstract: By 1743, readers of colonial newspapers had grown accustomed to reports of the religious revivals inaugurated by the English itinerant George Whitefield. But few were prepared for accounts of the bizarre and sensational events that took place in the port city of New London, Connecticut, in March of that year. According to the Boston Evening Post, the central character in the affair was the ailing and fanatical native-born itinerant James Davenport, whose "theatrical" preaching style and wild accusations against his fellow ministers had led to his arrest earlier in both Hartford and Boston. His chief accomplices were a devoted group of radical "New Lights" who, with Davenport's encouragement, had separated themselves from the Congregational church fifteen months earlier and formed their own church and an evangelical seminary known as the "Shepherd's Tent." Under the impression of messages "received from the Spirit in Dreams," Davenport carried his band of Separates into an orgy of religious enthusiasm that exceeded all bounds of decency and good order. By Sabbath afternoon, March 6, he had worked the people into such a frenzy that townsmen "ran to see if Murder or some other Mischief was not about to be done." Instead they witnessed the most remarkable event of the Great Awakening in New England. There, at Christophers's town wharf, Davenport and his followers gathered around a bonfire and cast into it a veritable library of Puritan classics. The catalogue of burned books was said to include works by such celebrated divines as Matthew Henry, Richard Sibbes, Increase Mather, and Benjamin Colman. The Post's writer heard the bookburners "sing Hallehuahs and Gloria Patri over the Pile, and I heard them with a loud voice declare, That the smoak of the Torments of such of the Authors of the above said Books as died in the same Belief as when they set them out, was now ascending in Hell in like manner as they saw the smoak of them books rise."-
TL;DR: There are several examples in the literature to show that the formation of subprotoplasts is favored by conditions of high osmoticum concentrations and the presence of elongated cells.
Abstract: There are several examples in the literature to show that the formation of subprotoplasts is favored by conditions of high osmoticum concentrations and the presence of elongated cells. As plant tissues are plasmolysed, some of the elongated cells will fragment into two or more parts. When the cell wall is removed with enzymes, the subprotoplasts are released into the medium. If elongated cells are not present, centrifugation or budding of protoplasts can be used, or large fragile cells can be obtained by a high auxin treatment. Each method gives mixed populations of subprotoplasts with protoplasts. Purified fractions are obtained by density gradient centrifugation, or by picking with a micropipet.
TL;DR: Differential cross sections for the time-reversed /sup 3/He(..gamma..,d)/sup 1/H for incident energies between 150 and 350 MeV at center-of-mass proton angles near 60/sup 0/ and 90/sup 1 0/ have been measured with an absolute uncertainty of less than 6% as discussed by the authors.
Abstract: Differential cross sections for /sup 3/He(..gamma..,d)/sup 1/H for incident energies between 150 and 350 MeV at center-of-mass proton angles near 60/sup 0/ and 90/sup 0/ have been measured with an absolute uncertainty of less than 6%. The experiment used a single-arm spectrometer, a gas target, and an uncollimated bremsstrahlung beam. The results are in good agreement with new measurements of the time-reversed reaction, /sup 2/H(p,/sup 3/He)..gamma.., giving no evidence for a violation of time-reversal invariance. The differential cross sections decrease smoothly with energy and show only a small contribution from the ..delta..(1232) resonance.
TL;DR: In this article, the relations between harmonic or fundamental currents in overhead three-phase circuits and the magnetic fields measured under the lines were derived and used to calculate harmonic currents in each conductor from the magnetic field data.
Abstract: This work derives the relations between harmonic or fundamental currents in overhead three-phase circuits and the magnetic fields measured under the lines. These relations are used to calculate harmonic currents in each conductor from the magnetic field data. Calculated and experimental field patterns are shown, and a specific technique for field measurements and current calculations is outlined. Laboratory results indicate that a good level of accuracy is attainable with this non-contact technique.
TL;DR: In this article, the authors propose a technique which reduces the large state estimation problem to a set of smaller least-squares problems plus the solution of a square system, which is used to partition the system into sub- networks whose states are estimated separately.
Abstract: Estimating the state of a large electric power system is an ill-conditioned computational task simply because of its size. This paper describes a technique which reduces the large state estimation problem to a set of smaller least-squares problems plus the solution of a square system. An observability algorithm developed earlier is used to partition the system into sub- networks whose states are estimated separately. These separate estimates are reconciled using the solution of an interconnecting subnetwork consisting entirely of measurements whose removal would render the full system unobservable. Under appropriate conditions, this partitioned state estimate is identical with the usual full least-squares estimate. Details of the implementation of this algorithm are given, and its application to the IEEE 30-bus network is described.
TL;DR: In this article, the authors used a doublet of achromatic lenses in which a quadrupole voltage may be applied to the magnetic poles of one of the lenses in order to rotate its principal section.
Abstract: An achromatic quadrupole lens contains an electric and a magnetic quadrupole lens operated at the proper field ratio Using a doublet of achromatic lenses in which a quadrupole voltage may be applied to the magnetic poles of one of the lenses in order to rotate its principal section, we have eliminated simultaneously what may be called three first order aberrations of a quadrupole doublet These are chromatic aberration, rotational misorientation, and focus By adding suitably chosen small potentials to the quadrupole excitation of an electric lens, 2nd order parasitic aberration may be compensated Experimental procedure for compensation is described The procedure appears capable of improvement, and further work is warranted Currently a beam of 600 keV protons with a width of 06 micron is obtained
TL;DR: A new continuous information theoretic analysis technique is presented that overcomes many of the problems in the other methods of analysis discussed, and clearly shows some of the misconceptions that are associated with statistical analysis techniques.
Abstract: Information theoretic and statistical techniques for determining the number of discernible levels in cutaneous receptor neurons are reviewed. Reasons for the large variance in these results are discussed. A new continuous information theoretic analysis technique is presented that overcomes many of the problems in the other methods of analysis discussed. Comparison of this new method of analysis with a statistical technique developed by Schreiner et al. (1978) clearly shows some of the misconceptions that are associated with statistical analysis techniques, and why these problems cannot arise in the new information theoretic technique discussed here.
TL;DR: An integrated or ‘weak’ solution approach to a distributed parameter system model for dynamic image sequences forms the basis for a feature extraction and motion estimation algorithm.
TL;DR: Differences between the timing, task use and characteristics of information whose source is a CLS and information whose sources are not a CLS are found, which have a variety of implications.
Abstract: This paper addresses the role of computerized literature search systems (CLS) in the transfer of scientific and technical information (STI). We consider how information acquired through computerized search differs in characteristics and usage from information acquired from other sources. Data was gathered from over 300 engineers and scientists working in five major US corporations involved in R & R work. We found differences between the timing, task use and characteristics of information whose source is a CLS and information whose source is not a CLS. These differences have a variety of implications. We also considered the demographic differences between users and non-users of CLS.
TL;DR: In this article, the reaction of anhydrous FeCl 3 with coal was studied using a number of techniques including X-ray diffraction, scanning electron microscopy, surface area determination and chemical analysis.
TL;DR: The most successful apomyoglobin reconstitution was achieved with the complex [Fe TAAB (An)2] (BF4)2, (An=accetonitrile, TAAb=[b,f,n] p1,5,9,13] -tetraazacyclo-hexadecine) which undergoes a color change from maroon-red to deep blue when exposed to apomyglobin this article.
Abstract: Reconstitution of apomyoglobin has been attempted with six transition metal complexes containing synthetic macrocyclic ligands and has been successful in several cases. The success of reconstitution has been judged by electronic absorption spectroscopy and ANS fluorescence analysis of solutions of the reconstituted proteins. The most dramatically successful reconstitution was achieved with the complex [Fe TAAB (An)2] (BF4)2, (An=accetonitrile, TAAB=[b,f,n] p1,5,9,13] -tetraazacyclo-hexadecine) which undergoes a color change from maroon-red to deep blue when exposed to apomyglobin. The electronic spectrum of the blue solution corresponds with the known spectrum of FeTAAB(meIm)2 2+ (MeIm=N-methylimidazole).
TL;DR: In this article, the effect of the Bragg and deformation reaction forces on acoustic propagation in simple metals was studied and it was shown that no significant alterations of the results obtained within the free-electron model are expected and that no change occurs in the position and strength of the helicon-phonon interaction.
Abstract: A study is given of the effect of the Bragg and deformation reaction forces on acoustic propagation in simple metals. We show that no significant alterations of the results obtained within the free-electron model are expected and that no change occurs in the position and strength of the helicon-phonon interaction.
TL;DR: T frequency response optimization methods for vibrating structures are developed for appending absorbers to the system and optimal design algorithms have been applied to a 39 degree-of-freedom helicopter model with discrete conventional absorbers and beam absorbers.
Abstract: T frequency response optimization methods for vibrating structures are developed for appending absorbers to the system The methods are suitable for discrete models with a large number of degrees of freedom and are applied to obtain optimal broadband response Reanalysis and modal synthesis techniques are used in the structural dynamic analysis phase of the design algorithm and optimization is carried out by a feasible directions approach These optimal design algorithms have been applied to a 39 degree-of-freedom helicopter model with discrete conventional absorbers and beam absorbers
TL;DR: In this article, a simple reliable method to measure residual adsorption capacity (RAC) of charcoal adsorbers on which a gas is physisorbed has been developed.
Abstract: A simple reliable method to measure Residual Adsorption Capacity (RAC) of charcoal adsorbers on which a gas is physisorbed has been developed. The method consists of passing a pulse of weakly adsorbed gas(es) through the adsorption filter(s) and measuring the retention time. This retention time is then correlated to the residual adsorption capacity. In order to predict the retention time-RAC relationship for filters with various configurations and bulk densities, this pulse test was mathematically modeled. The numerical solution of the model involved estimating the transport rate parameters, using existing correlations and the moment technique. A perturbation analysis indicated that the accuracy of the model is closely associated with the estimates of adsorption equilibrium constant and the intraparticle diffusion coefficient of the test gas. The model is shown to be accurate in predicting the RAC of an adsorber under dry and humid conditions from a limited data set.
On a mis au point une methode simple et fiable pour mesurer la capacite residuelle d'adsorption (RAC) d'adsorbants a base de charbon de bois sur lesquels un gaz est adsorbe physiquement. La methode consiste a faire passer une impulsion de gaz (un ou plusieurs) faiblement adsorbe a travers le (ou les) filtre(s) d'adsorption et a mesurer le temps de retention; on etablit ensuite une correlation entre cette retention et la capacite residuelle d'adsorption. Pour prevoir la sorption dans le cas des filtres possedant diverses configurations et densites globales, on a modelise mathematiquement l'essai d'impulsion. La solution numerique du modele a implique l'evaluation des parametres des vitesses de transfert en employant des correlations existantes et la methode des moments. Une analyse de perturbation a indique que l'exactitude du modele etait etroitement associee aux estimations de la constante d'equilibre d'adsorption et du coefficient de diffusion intraparticulaire du gaz utilise. Les resultats obtenus par le modele se sont averes exacts dans le cas de la prevision de la capacite residuelle d'adsorption d'un adsorbant, dans des conditions seches et humides, pour un nombre limite de donnees.