Effects of RFCC Spent Catalyst on Some Physicomechanical Properties of Portland Cement Paste

No. 263, Ostad Nejatollahi St., Tehran, Ira

Three-Machine Flowshop Scheduling Problem to Minimize Total Completion Time with Bounded Setup and Processing Times

The three-machine flowshop scheduling problem to minimize total completion time is studied where setup times are treated as separate from processing times. Setup and processing times of all jobs on all machines are unknown variables before the actual occurrence of these times. The lower and upper bounds for setup and processing times of each job on each machine is the only information that is available. In such a scheduling environment, there may not exist a unique schedule that remains optimal for all possible realizations of setup and processing times. Therefore, it is desired to obtain a set of dominating schedules (which dominate all other schedules) if possible. The objective for such a scheduling environment is to reduce the size of dominating schedule set. We obtain global and local dominance relations for a three-machine flowshop scheduling problem. Furthermore, we illustrate the use of dominance relations by numerical examples and conduct computational experiments on randomly generated problems to measure the effectiveness of the developed dominance relations. The computational experiments show that the developed dominance relations are quite helpful in reducing the size of dominating schedules

EFFECTS OF BLAST-FURNACE SLAG ON NATURAL POZZOLAN-BASED GEOPOLYMER CEMENT

A number of geopolymer cement mixes were designed and produced by alkali-activation of a pumice-type natural pozzolan. Effects of blast-furnace slag on basic engineering properties of the mixes were studied. Different engineering properties of the mixes such as setting times and 28-day compressive strength were studied at different amounts of blast-furnace slag, sodium oxide content, and water-to-cement ratio. The mix comprising of 5 wt.% blast-furnace slag and 8 wt.% Na2O with a water-to-dry binder ratio of 0.30 exhibits the highest 28-day compressive strength, i.e. 36 MPa. Mixes containing 5 wt.% of ground granulated blast furnace slag showed the least efflorescence or best soundness. Laboratory techniques of X-ray diffractometry (XRD), fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were utilized for characterizing a number of mixes and studying their molecular and micro-structure. Investigations done by scanning electron microscopy confirm that smaller blast-furnace slag particles react totally while the larger ones react partially with alkaline activators and contribute to the formation of a composite microstructure

BULANIK MANTIKLA SICAKLIK VE NEMİN KONTROLU VE SİSTEMİN GERÇEKLEŞTİRİLMESİ *

Bu çalışmada, bulanık mantık yöntemiyle sıcaklık ve nem parametreleri kontrol edilmiş ve sistem gerçekleştirilmiştir. Çalışmada bulanık mantığın, bulanık koşullu çıkarım mekanizması kullanılmış ve bu yöntemin sıcaklık ve nem gibi parametreleri daha esnek olarak nasıl kontrol edebildiği gösterilmiştir. Sistem donanım olarak bilgisayar, analog-dijital dönüştürücü kartı, sıcaklık ve nem sensörleri ve sıcaklık ve nem ölçme devrelerinden oluşmaktadır. Sıcaklık sensörü olarak LM335 ve nem sensörü olarak ta kapasitif bir sensör kullanılmıştır. Bu işlemi gerçekleştirecek olan sistemin algoritması geliştirilmiş ve kontrol programı QBASIC programlama dilinde yazılmıştır

Permutation flowshops with exact time lags to minimize maximum lateness

In this paper, we investigate the m-machine permutation flowshop scheduling problem where exact time lags are defined between consecutive operations of every job. The objective is to minimize the maximum lateness. We introduce different job types, depending on their time lags. We study polynomial special cases and provide a dominance relation. We derive lower and upper bounds that are integrated in a branch-and-bound procedure to solve the problem. We perform a computational analysis to evaluate the efficiency of the proposed method

Permutation flow shops with exact time lags to minimise maximum lateness

International audienceIn this paper we investigate the m-machine permutation flow shop scheduling problem where exact time lags are defined between consecutive operations of every job. This generic model can be used for the study and analysis of various real situations that may arise, for instance, in the food-producing, pharmaceutical and steel industries. The objective is to minimise the maximum lateness. We study polynomial special cases and provide a dominance relation. We derive lower and upper bounds that are integrated in a branch-and-bound procedure to solve the problem. Three branching schemes are proposed and compared. We perform a computational analysis to evaluate the efficiency of the developed method

Monte Carlo study of electron dose distributions produced by the elekta precise linear accelerator

BackgroundMonte Carlo simulation of radiation transport is considered to be one of the most accurate methods of radiation therapy dose calculation and has ability to reduce the uncertainty in the calculated dose to a few percent.Aims(1) To study the efficacy of the MCNP4C Monte Carlo code to simulate the dose distribution in a homogeneous medium produced by electron beams from the Elekta Precise linear accelerator. (2) To quantify the effect of introduction of various components to the simulated geometry for the above machine.Materials/MethodsFull Monte Carlo simulation of the detailed geometry of the Precise treatment head for 8 and 15 MeV energies and 10×10 applicator was performed. Experimental depth dose and lateral profiles at 2cm depth were measured using a P-type diode detector with a 2.5 mm diameter. To quantify the effects of different parts of the treatment head, seven cases were simulated for a 15 MeV beam to reflect increasing levels of complexity, by step-wise introduction of beam divergence, primary and secondary scattering foils, secondary collimators, applicator, Mirror and Mylar screen.ResultsThe discrepancy between measured and calculated data is within 2%/2 mm at both 8 and 15 MeV. In terms of the mean and most probable energies at the surface, the difference wa

Assessment of different MCNP Monte Carlo codes in electron absorbed dose

BackgroundMCNP is a general-purpose Monte Carlo code for simulation of neutrons, photons and electrons or coupled neutron/photon/electron transport. This code is based on ETRAN/ITS codes. There are different versions of this code.AimThis work aims to compare the more recently released MCNP codes with the earlier version in terms of the central axis absorbed dose (CADD), the energy spectrum and the computational efficiency. MCNP codes 4A, 4B, 4C, X and 5 were compared for a 10 MeV electron beam in water.Materials/MethodsThe energy spectra of electrons were scored on the phantom surface and planes 3 and 5cm deep using F2 tally subdivided into 0.1 MeV energy bins. This tally also was repeated for 4A, 4B, 4C and X with smaller energy bins (0.05 MeV). The simulated geometry and other input parameters were kept the same. Both the default and ITS energy indexing algorithms (EIA) were used in 4B, 4C and X, while only the default EIA was employed in 4A and 5.ResultsWith default indexing, X and 5 showed no difference in CADD compared to 4B and 4C and were within 3% of 4A. We found no differences in CADD between codes when 4B, 4C and X were used with ITS indexing. The ITS algorithm improved computational efficiency. For the energy spectrum at the phantom surface, all codes except X show very similar results (within 2%). However, changing the energy indexing to ITS as well as using a 0.05 MeV bin removed this discrepancy at the surface for X code.ConclusionsWhile, under the examined conditions, versions 4B and later behaved similarly in terms of the resulting CADD, the ITS indexing should be used due to its agreement with measurements and computational efficiency

Inflation with improved D3-brane potential and the fine tunings associated with the model

We investigate brane-antibrane inflation in a warped deformed conifold background that includes contributions to the potential arising from imaginary anti-self-dual (IASD) fluxes including the term with irrational scaling dimension discovered recently. We find that the model can give rise to required number of e-foldings; observational constraint on COBE normalization is easily satisfied and low value of the tensor to scalar ratio of perturbations is achieved. We observe that these corrections to the effective potential help in relaxing the severe fine tunings associated with the earlier analysis.Comment: 8 pages, 4 figures; typos corrected, minor clarifications and new refs added, to appear in epj