Genetically evolved radial basis function network based prediction of drill flank wear

The most important factor that governs the performance of a radial basis function network (RBFN) is the optimization of the network architecture, i.e. determining the exact number of radial basis functions (RBFs) in the hidden layer that can best minimize the error between the actual and network outputs. This work presents a genetic algorithm (GA) based evolution of optimal RBFN architecture and compares its performance with the conventional RBFN training procedure employing a two stage methodology, i.e. utilizing the k-means clustering algorithm for the unsupervised training in the first stage, and using linear supervised techniques for subsequent error minimization in the second stage. The validation of the proposed methodology is carried out for the prediction of flank wear in the drilling process following a series of experiments involving high speed steel (HSS) drills for drilling holes on mild-steel workpieces. The genetically grown RBFN not only provides an improved network performance, it is also computationally efficient as it eliminates the need for the error minimization routine in the second stage training of RBFN.     

An investigation of 1H and 13C longitudinal relaxation and relaxation in the rotating frame in solid poly(N‐vinylcarbazole)

¹H and ¹³C longitudinal relaxation times (T₁) and relaxation times in the rotating frame (T_1ρ) have been measured for poly(N‐vinylcarbazole) in the solid state in air and nitrogen atmospheres in an attempt to elucidate molecular motions. In air, the T₁ relaxation of both ¹H and ¹³C was dominated by interaction with absorbed paramagnetic oxygen. In nitrogen, the ¹³C T₁ relaxation times were long (>300 s) and were averaged by ¹³C–¹³C spin diffusion. The ¹³C T_1ρ relaxation times showed an exponential dependence on the strength of the rotating ¹³C magnetic field and were thus controlled by spin–spin processes rather than spin–lattice processes. © 2001 Society of Chemical Industry     

Size effects in micro drilling of carbon fiber reinforced plastic composite

The contribution presents investigations regarding the size effects on cutting forces in micro drilling of carbon fiber reinforced plastic composite. Generally, size effect is described as non-linear increase of specific cutting force with decreasing chip thickness. Specific cutting forces are determined by dividing cutting force components by chip area. In a mathematical model, specific cutting force is expressed as a function of the ratio of undeformed chip thickness to cutting edge radius. The coefficients of the model are determined by regression analysis using experimental results. Non-linear increase of specific cutting force is observed when the ratio decreases, especially when the ratio is less than unity.     

Synthesis and preliminary CNS depressant activity evaluation of new 3-[(3-substituted-5-methyl-4-thiazolidinon-2-ylidene)hydrazono]-1H-2- indolinones and 3-[(2-thioxo-3-substituted-4,5-imidazolidinedion-1-yl) imino]-1H-2-indolinones

A series of (+/-) 3-[(3-substituted-5-methyl-4-thiazolidinon-2- ylidene)hydrazono]-1H-2-indolinones (2a-h) and 3-[(2-thioxo-3-substituted-4,5-imidazolidinedion-1-yl)imino] -1H-2-indolinones (3a-g) were synthesized by the cyclization of 3-(4-substituted-thiosemicarbazono)-1H-2-indolinones (1a-h) with ethyl 2-bromopropionate in anydrous ethanolic medium and oxalyl chloride in anhydrous diethyl ether, respectively. The structures of 2 and 3 were confirmed by analytical and spectral data (IR, 1H NMR, 13C NMR, and EIMS). The configuration of 3 was assigned on the basis of 1H NMR and 13C NMR data. 2c, 2d, 2g, 2h, and 3a-g were evaluated for anticonvulsant activity against maximal electroshock (MES) and subcutaneous pentylenetetrazol (ScMet) induced seizures. Among the compounds tested, only 2d exhibited some activity in anticonvulsant identification (Phase I) trials in mice. 2a, 2b, 2d, 2g, 2h, and 3a-g were additionally tested for potentiating effects on pentobarbital induced hypnosis in mice. All of the test compounds increased the sleeping time of pentobarbital significantly (p < 0.05) and the most potent compound was found to be 3a.     

Granular transport through flighted rotary drums operated at optimum-loading: Mathematical model

Abstract

This paper discusses the transport of granular materials through flighted rotary drums operated at the optimum loading. A mathematical model is derived from the force balance acting on a single traveling particle, to predict the mean residence time of transportation. Based on the available parameters of mean height of falling curtains and final discharge angle, this model can be helpful to estimate the appropriate solid feeding rate. Two steps were followed to implement the use of the model. Firstly, experiments were carried out on a batch rotary drum to obtain the needed input parameters. Then, a case study of a small capacity rotary dryer was considered. In both steps, the drum was operated at the optimum loading. The model results were compared with other correlation from the literature for two cases of solid and air flows: con-current and counter current. Based on the results, a factor is introduced for generalized correlation from literature.     

Thermoluminescent spectra of rare earth doped MgB4O7 dosemeters

This paper presents X ray excited TL spectra of magnesium borate doped with either single rare earth ions Dy or Tm, or co-doped with Dy/Tm, Tm/Mn or Dy/Tb. Intrinsic emission from the host material is in the UV/blue region at approximately 375 nm, with a tail extending to 200 nm. The main dosimetric peak is detected at approximately 180 degrees C but slight differences are noted between the glow peak maxima from the different rare earth ions and there were changes following thermal treatments. The results are discussed according to the interaction between trapping and rare earth sites.     

Spectrally resolved luminescence of undoped and Dy3+ doped Na2SO4

Structural phase transitions influence the luminescence characteristics by modifying the spectra, sensitivity and luminescence efficiency in each phase. This has implications for dosimetric materials both for sensitivity and reproducibility. Previous work with dosemeter materials has not documented effects of different phases on thermoluminescence but Na2SO4 exists in several phases in the temperature range of interest for thermoluminescence dosimetry. Therefore spectrally resolved TL and radiothermoluminescence analyses of undoped and Dy3+ doped Na2SO4 have been performed. Dramatic differences between TL of slow cooled and quenched Na2SO4:Dy are explained in terms of the initial phase of the samples at room temperature. For undoped material the effect of phase conversions during heating shift the wavelengths of the emission bands. A model of Dy in small precipitate phases is considered.