Total Number Of Groups Research Articles

Effect of increased basicity of activated carbon surface on valeric acid adsorption from aqueous solution activated carbon

Two types of activated carbons of different origins were used to study the adsorption of valeric acid from aqueous solution. Nitrogen-containing basic groups were introduced into the surface by impregnating the initial samples with urea followed by heat treatment at 1223 K. Characterization of the surface was done using the following techniques: Boehm titration, potentiometric titration, thermal analysis and sorption of nitrogen. Valeric acid adsorption isotherms were measured at 333 K and fitted to the Freundlich equation. A direct correlation of the capacity coefficients with both the total number of groups and the volume of micropores smaller than 10 A was found. The amount of valeric acid adsorbed on activated carbons, calculated from the isotherms, showed similar trend. The results obtained from DTG analysis showed that the strongly adsorbed amount of valeric acid per unit surface area increases with an increase in the density of basic groups. On the other hand, the amount adsorbed decreases with an increase in the density of acidic groups on the surface. This is related to attractive/repulsive interactions of adsorbate with surface species.

A new grouping method to minimize surplus parts in selective assembly for complex assemblies

Selective assembly is the method of obtaining high precision assemblies from relatively low precision components. The mating parts are manufactured with wide tolerances. The mating part population is then partitioned to form selective groups. The corresponding selective groups are then assembled interchangeably. The mating parts are manufactured in different processes and in different machines. The standard deviation of the mating parts will be different. The probability of the number of parts in the selective group cannot be the same. A large number of surplus parts is expected according to the difference in standard deviations of the mating parts. In this paper, a complex assembly with three mating parts (as in a ball bearing: an inner race, ball and outer race) is considered for analysis. A new method is proposed for partitioning the lots to form selective groups. By this method, the number of surplus parts is reduced to a large extent. The variation in clearance is minimized and the total number of groups is also less when compared with traditional methods.

Capturing dynamic memory reference behavior with adaptive cache topology

Memory references exhibit locality and are therefore not uniformly distributed across the sets of a cache. This skew reduces the effectiveness of a cache because it results in the caching of a considerable number of less-recently-used lines which are less likely to be re-referenced before they are replaced. In this paper, we describe a technique that dynamically identifies these less-recently-used lines and effectively utilizes the cache frames they occupy to more accurately approximate the global least-recently-used replacement policy while maintaining the fast access time of a direct-mapped cache. We also explore the idea of using these underutilized cache frames to reduce cache misses through data prefetching. In the proposed design, the possible locations that a line can reside in is not predetermined. Instead, the cache is dynamically partitioned into groups of cache lines. Because both the total number of groups and the individual group associativity adapt to the dynamic reference pattern, we call this design the adaptive group-associative cache. Performance evaluation using trace-driven simulations of the TPC-C benchmark and selected programs from the SPEC95 benchmark suite shows that the group-associative cache is able to achieve a hit ratio that is consistently better than that of a 4-way set-associative cache. For some of the workloads, the hit ratio approaches that of a fully-associative cache.

Capturing dynamic memory reference behavior with adaptive cache topology

Memory references exhibit locality and are therefore not uniformly distributed across the sets of a cache. This skew reduces the effectiveness of a cache because it results in the caching of a considerable number of less-recently-used lines which are less likely to be re-referenced before they are replaced. In this paper, we describe a technique that dynamically identifies these less-recently-used lines and effectively utilizes the cache frames they occupy to more accurately approximate the global least-recently-used replacement policy while maintaining the fast access time of a direct-mapped cache. We also explore the idea of using these underutilized cache frames to reduce cache misses through data prefetching. In the proposed design, the possible locations that a line can reside in is not predetermined. Instead, the cache is dynamically partitioned into groups of cache lines. Because both the total number of groups and the individual group associativity adapt to the dynamic reference pattern, we call this design the adaptive group-associative cache. Performance evaluation using trace-driven simulations of the TPC-C benchmark and selected programs from the SPEC95 benchmark suite shows that the group-associative cache is able to achieve a hit ratio that is consistently better than that of a 4-way set-associative cache. For some of the workloads, the hit ratio approaches that of a fully-associative cache.

Diurnal grouping and activity patterns of the Pyrenean chamois in winter

The relationships between group size, activity patterns, and time of day were studied during a mild winter in a protected population of Isard or Pyrenean chamois (Rupicapra pyrenaica pyrenaica) in open montane pastures in the bottom of a central valley, bordered by a beech forest. The size and the total number of groups increased progressively from dawn to the middle of the afternoon. Nearly half of the animals foraged early in the morning, while about two out of five were moving. As the day proceeded, the allocation of time for foraging increased regularly until approximately 3/4 of the animals were observed foraging at about 17:00. Foraging increased initially at the expense of moving, and later to both moving and standing. Then, just before dusk, both group size and time devoted to foraging decreased, as individuals returned to the beech forest to rest during the night in a sheltered habitat. The relative influence of weather conditions and of the digestive physiology of Pyrenean chamois on this spatio...

Procedure for tightening fastening bolts of detachable joints of high-pressure vessels

The essential feature of the stepwise-equalizing procedure is that for a total number of groups of bolts to be tightened the first z 1 groups of bolts in the first round are loaded by the cound-equalizing procedure [i], i.e., the first group of bolts is loaded with the maximally admissible stress Qa, the second group of bolts is loaded up to the level equaling the residual stress of the first group which was partially relieved during tightening of the second group of bolts, the third group is loaded up to the level equaling the partially relieved bolts of the first and second groups, etc. ; the z-th group of bolts is loaded with a specific calculated stress Qz. For further tightening the bolts are loaded in the first (up to the last n group) and second (up to z i) rounds by a stress equaling the residual loads in the previously tightened groups beginning from the z-th.

Selected Physico-Chemical Characteristics of Bovine Colostrum Immunoglobulin

Three immunoglobulin preparations isolated from bovine colostrum by ammonium sulfate fractionation and repeated ion-exchange column chromatography on DEAE-Sephadex A-50 had sedimentation values ranging from 18.2 to 19.8 and extinction coefficients of 11.8 ± .2. Carbohydrate content was 10.78 ± .31% consisting of 5.13 ± .12% hexoses, 1.25 ± .05% fucose, 1.40 ± .05% sialic acid, and 2.90 ± .09% hexo-samines. The immunoglobulin preparations contained no free sulfhydryl groups. However, the total number of groups was 43.6 per mole of immunoglobulin based on an approximate molecular weight of 900,000, indicating that immunoglobulin contained 21 disulfide bonds per mole.

The interpretation of complementation data.

The evidence for complementation maps being linear is examined by analysis of all known complementation maps in micro-organisms, and by constructing maps from mutants randomly sampled from amongst those at theleu-2locus inNeurosporawith known complementing properties. Eleven loci out of thirty-five examined in six micro-organisms have non-linear complementation maps. Two linear maps,his-3andad-3b(having 25 and 35 complementation groups respectively) have a sufficiently large number of groups for it to be likely that if they do not remain linear on testing further mutants, they will at least have a lower frequency of mutants exceptional to linearity than known non-linear loci. On the basis of maps made from mutants sampled from theleu-2data, it seemed unlikely that non-linearity would be observed with less than 24 complementing mutants or 13 complementing groups in the sample, and therefore many loci with linear maps are likely to be found to have non-linear maps when larger samples of mutants are tested. This conclusion is important in attempting to correlate the structure of complementation maps with recombination maps and with functional data concerning enzyme activities.The relationship between the number of complementing mutants, number of groups and number of units at theleu-2locus is described and a statistical method of determining the total number of groups at a locus is discussed.Known complex complementation maps have been replotted according to consistent rules, and are illustrated in a shorthand form. The form of the complex maps is discussed in relation to current hypotheses concerning the interpretation of complementation maps. In particular an interpretation of the ‘circular’leu-2map is given in terms of the theory of complementation proposed by Crick & Orgel (1964).