Round-robin distribution

Distribution of tasks (labeled A-H) across three processes using a round-robin distribution. 

Processes request tasks (atom quartets) by calling the function get quartet, which has been implemented in both a dynamic and a static version. The dynamic work distribution uses a manager-worker model with a manager process dedicated to distributing tasks to the other processes, whereas the static version employs a round-robin distribution of tasks. When the number of processes is small, fhe sfafic scheme achieves the best parallel performance because the dynamic scheme, when run on p processes, uses only p - 1 processes for compulation. As the number of processes increases, however, the parallel performance for the dynamic task distribution surpasses that of the static scheme, whose efficiency is reduced by load imbalance. Wifh fhe entire Fock and density matrix available to every process, no communication is required during the computation of the Fock matrix other than the fetching of tasks in the dynamic scheme. After all ABCD tasks have been processed, a global summation is required to add the contributions to the Fock matrix from all processes and send the result to every process. 

The molten salt standard program was initiated at Rensselaer Polytechnic Institute (RPI) in 1973 because of difficulties being encountered with accuracy estimates in the NBS-NSRDS molten salt series. The density, surface tension, electrical conductivity, and viscosity of KNO3 and NaCl were measured by seven laboratories over the world using samples distributed by RPI. The data from these round-robin measurements of raw properties were submitted to RPI for evaluation. Their recommendations are summarized in Table 2. 

The development of CE analytical methods for CW-related compounds has been directed primarily toward the analysis of these compounds in environmental matrices such as soil and water. These methods have been used in the analysis of samples distributed as part of the interlaboratory comparisons exercises, the so-called round-robin exercises coordinated by Finland, and more recently, the OPCW Laboratory Proficiency Testing. 

All materials subject to size reduction through grinding will exhibit a distribution of particle sizes, often skewed in shape, with the result that a single estimate of size will not represent the sample as a whole. In addition, the grinding of multiphase samples most often results in differential size reduction of hard and soft phases. In practice, the difficulty in obtaining an accurate estimate of individual particle sizes usually means that analysts make an informed guess at the value of D. Thus, the value used may be empirically based to achieve a desired phase abundance rather than a value based on sound measurement. Widespread misuse of microabsorption correction was clearly demonstrated in the lUCr quantitative phase analysis round robin. ... 

The data sets distributed by the CPD for the QPA round robin are a useful resource for users aiming to develop and test their skills in applying various techniques. All data sets, in formats suitable for most of the commonly used software, can be found at http //www.mx.iucr.org/iucr-top/comm/cpd/QARR/ data-kit.htm. 

Later Von Dreele implemented the general description of texture by spherical harmonics in GSAS. Von Dreele proved that, by using this description, beside the robustness of the texture correction in the Rietveld method it is also possible to perform a reliable quantitative texture analysis. He measured by neutron time-of-flight diffraction a standard calcite sample previously used for a texture round robin. The patterns from different detector banks and sample orientations were processed by GSAS, refining the harmonic coefficients simultaneously with the structural and other parameters. Six pole distributions calculated from the refined harmonic coefficients and used as input in the... 

For the determination of the orientation distribution function it is necessary to record diffraction patterns successively by rotating the sample on a goniometer, as was shown in Section 12.1.4.2. The patterns must be measured in a large number of points (, y) scattered more or less uniformly on a hemisphere. It is difficult to evaluate beforehand how many such points are necessary for a reliable determination of the ODE. For a calcite sample previously used in a texture round robin Von Dreele recorded neutron time of flight diffraction patterns in about 50 points (T, y). All patterns were processed by GSAS simultaneously and six pole distributions calculated from the refined harmonic coefficients were further used as input in the WIMV inversion routine. An ODF similar to those obtained in the texture round robin resulted, but its dependence on the number of points in the space (T, y) was not examined. 

A few years ago, an ad hoc group of workers interested in coal minerals. The Mineral Matter in Coal Group, prepared and distributed a round-robin low temperature ash to ten laboratories. Each laboratory was to prepare, mount and quantify the mineral components in the ash by their respective XRD techniques. The data were then compared. Even though a wide variety of techniques was used for each phase of the analysis, with the exception of the clay mineral estimates made by one laboratory (significantly lower than the others) and the pyrite estimate made by another (too high), the data compared reasonably well. The averages of all the submitted estimates are summarized in Table III. 

Many HPLC methods for phospholipids have been developed, but chromatographic resolution and dynamics of detection are not always satisfactory. For each source of phospholipids, special standards are needed due to the different distribution of fatty acids. These standards are expensive and in some cases are not available. Another problem is represented by the analysis of phospholipids in complex matrices. In many cases, separation is impossible or very difficult, not least due to the surface activity, which is desired in the application of phospholipids, but which complicates the analysis of these compounds. Therefore, a method is needed which is selective in the detection of phospholipids in order to avoid a separation from the matrix. The P NMR spectroscopy of phospholipids meets these requirements. The I.L.P.S. (Internationa Lecithin and Phospholipid Society) has chosen the P NMR method as the reference method [62],[63],[64]. It has been tested world-wide by round robin tests in comparison to various HPLC and TLC methods. With triphenylphosphate as internal standard, a pulse angle of 15°, 10-s relaxation delay, and 32-256 accumulations, the method has a precision of <0,5%. 

Multiple techniques can be used to measure the particle size distribution, for example electrozone sensing, sedimentation, laser diffraction, and microscopy. With the exception of microscopy, they all require calibration and the results depend on the technique. For example, in a round-robin study reported in Reference 4, the commonly used electrical sensing zone technique (Coulter Counter) was compared to microscopy and sedimentation. The average particle size determined by the electrical sensing zone method was by about 25%... 

Outline of a simple round-robin static task distribution. The number of tasks is ntask/ P is the number of processes, and this proc is the process ID. 

Select a distribution scheme, for example, round-robin or recursive... 

Two parallel algorithms for two-electron integral computation using static load balancing are outlined in Figure 7.1. The algorithms, designated (a) and (b), both employ a static work distribution scheme with a round-robin... 

Here, process iterand is a thread-safe routine that produces elements of the X vector, and the programmer has explicitly distributed the work among the threads in a round-robin fashion. 

As mentioned earlier, all synthetic polymers have finite MWD and the measurement of MWD is usually the first step in the characterization of polymers. SEC has been the most widely employed method for the MWD measurements of polymers. In the SEC analysis, the precision of the measurements depends on various factors in the operation of the instrument and the data reduction [1,3j. Various efforts including round robin tests to establish a standardized procedure in the SEC analysis have been made [62, 63]. However, even for linear homopolymers there is an intrinsic limitation of SEC to measure the precise MWD due to the band-broadening problem, in particular for the polymers with narrow molecular weight distribution [64]. 

For standardization of the water uptake test, multiple organizations conducted the round robin test using common samples and procedures. Based on their results, methods (proposal) to determine water uptake and the rate of water absorption are being developed. A written inquiry was also distributed to the member companies of the Polymer Materials Center regarding water upUdce. Currently, Ihe standard for water uptake has not been established anywhere in the world. It seems important first to establish the standardization of Ihe water uptake testing method for superabsorbent polymers and then to make it die international standard. The testing mediods (proposal) shown here are still under discussion and when it is standardized by JIS, there may be partial modification. 

This paper discusses an attempt to prepare and characterize a standardized crosslinked rubber. By careful control of preparations and cure conditions, it should be possible to obtain specimens whose properties are reproducible from batch to batch. Distribution of such materials to those doing research on the viscoelastic behavior of cross-linked polymeric systems will stimulate a rapid advance in our understanding of such systems. Moreover, even in cases where research studies are not intended, they can serve as useful materials for apparatus calibration or for round robin tests. 

As an aid for the users in determining the possibility of bias, calculated Cg distributed for the round robin sample is listed in Table 2 as the Expected Concentration. The average value for each Cg isomer as calculated from the reported concentrations is listed as Average Concentration Reported. ... 

The gel content is determined indirectly from the amount of soluble fraction and directly by weighing the dried gel. Examples of the reproducibility of the data by round-robin tests are given for two SBR copolymers and three NBRs of 0 to 85 % gel content. For the zero sample the standard deviation is as high as 100% indicating that a very small amount of gel may be distributed non-uniformly. The standard deviations for 50-85% gel samples are at most a few per cent. 

In the second round-robin tests discussed earlier (Ferraris et al. 2002b), over 30% of the participants used LD with dry powders (dry LD) and over 60% used wet LD. Overall results after statistical analysis were very comparable over the whole distribution for the cement SRM 114p (Figure 10.6). The main challenge for both wet and dry is a correct dispersion of the powder either in the liquid to form a suspension or in gas to form an aerosol. In liquids, the use of ultrasonic treatment and dispersants can enhance the dispersion and improve reproducibility. In dry LD the compressed air or vacuum pressure used to disperse the particles can be varied. As can be seen from Figure 10.6, when dispersion is optimised, dry and wet... 

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