A dynamic programming approach for batch sizing in a multi-stage production process with random yields

This paper proposes a dynamic programming approach to modeling and determining batch sizes in a single period, multi-stage production process with random yields for each stage. To improve the computational performance of the proposed approach, a statistical bound is developed. A key decision incorporated into the model is whether to continue onto the next stage of processing or to scrap the entire current batch of product. This decision is based on the expected total profit from the remaining items for processing following the removal of all defectives. The decisions involving the locations of test stations after stages are also incorporated into the modeling approach.     

Solvent and central metal effects on the photophysical and photochemical properties of 4-benzyloxybenzoxy substituted phthalocyanines

The synthesis and characterization of new peripherally tetra-4-benzyloxybenzoxy substituted metal-free, zinc and lead phthalocyanines are described for the first time in this study. The influence of various organic solvents and the nature of the central metal ion on the spectroscopic, photophysical and photochemical properties has been investigated. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in different solvents. Photophysical and photochemical properties of phthalocyanine compounds are very useful for photodynamic therapy applications. Especially high singlet oxygen quantum yields are very important for Type II mechanism. The studied phthalocyanine compounds showed good singlet oxygen generation and these compounds show potential as Type II photosensitizers. The fluorescences of the studied compounds are effectively quenched by 1,4-benzoquinone in different solvents.     

Structure and Luminescent Properties of the 4-Arylidene-2-Aryl-5-Oxazolones(Azlactones)In Solution and Crystalline State

Experimental and theoretical evaluations have proven that very low fluorescence quantum yields of azlactones in solution are not caused by an efficient inter system crossing from S₁*(ππ) to T*(nπ) states, but rather from solvation and steric effects, that result in non-planarity of the molecular system. High fluorescence quantum yields in the solid state are attributed to the planarity of the azlactone molecule upon packing into the crystal lattice. Supporting evidence was found upon observation of the excited state proton transfer (ESIPT) bands of fluorescence emissions of o-hydroxyarylidene derivatives. The photoinstability of azlactones in liquid states are attributed to photochemical E-Z isomerization and cleavage of the hetero ring α to the carbonyl group.     

Bifurcation in the stable manifold of the bioreactor with <Emphasis Type="Italic">n</Emphasis>th and <Emphasis Type="Italic">m</Emphasis>th order polynomial yields

The three dimensional chemostat with nth and mth order polynomial yields, instead of the particular one such as A + BS, A + BS ², A + BS ³, A + BS ⁴, A + BS ² + CS ³ and A + BS ⁿ , is proposed. The existence of limit cycles in the two-dimensional stable manifold, the Hopf bifurcation and the stability of the periodic solution created by the bifurcation are proved.     

利用啁啾激光调制分子谐波信号

数值研究了啁啾激光驱动H_2~+辐射谐波的特点.结果表明,(1)在低强度和高强度激光驱动下,谐波光谱分别呈现红移和蓝移现象.引入正负向啁啾参数后,谐波频移和谐波辐射强度都可以得到调控.(2)谐波光谱在高强度激光驱动下呈现非奇次谐波.理论分析表明,非奇次谐波产生的原因是双H核频移不一致所导致的不对称相消干涉引起的.     

Structure Effect on K Shell Fluorescence Parameters at Bis-4-Bromobenzyl-1,2,4-Triazol-3-Ones

In this study; the effect of the electron density over the Br atoms raising with increasing number of CH₂ group using the results of the K X-ray cross-sections and average fluorescence yields of bromine in quaternary-imidazole ring. In the experimental set-up, 50 mCi 241Am source and a collimated Ultra-LEGe detector were used. The electron density on the Br atoms raises according to the number of the CH₂ groups on the contrary of the inductive effect. The decreasing of the X-ray fluorescence parameters is interested with the increasing the electron density of Br atoms.     

载能Ni原子斜入射Pt(111)表面的分子动力学模拟

采用嵌入原子方法的原子间相互作用势,利用分子动力学模拟,详细研究不同角度入射的载能Ni原子在Pt(111)基体表面的沉积过程.结果表明,随着入射角度θ从0°增加到80°,溅射产额、表面吸附原子产额、空位产额的变化情况均可按入射角度近似地分为θ≤20°,20° < θ < 60°和θ≥60°三个区域.当θ≤20°时,载能沉积对基体表面的影响与垂直入射时的情况类似,表面吸附原子的分布较为集中,入射原子容易达到基体表面第二层及以下,对基体内部晶格产生-定的影响;在20° < θ < 60°的范围内,入射原子的注入深度有所下降,对基体内部晶格的影响减小,表面吸附原子的分布较为均匀,有利于薄膜的均匀成核与层状生长;当θ≥60°时,所有入射原子均直接被基体表面反射,表面吸附原子产额、溅射产额、表面空位产额均接近0,载能沉积作用没有体现.     

The effect of an external magnetic field on the L subshell X-ray fluorescence cross sections and L subshell fluorescence yields in elements 73 ≤ Z ≤ 92 by 59.54 keV photons

L_i (i = 1, 2 and 3) X-ray fluorescence cross sections for Ta, W, Au, Hg, Tl, Pb, Bi, Th and U have been measured using the 59.54 keV incident photons energy in the external magnetic field of intensity +0.60 T. The values of L_i subshell fluorescence yields (w₁$w_1$, w₂$w_2$ and w₃$w_3$) have been measured for the same elements using the previously measured cross section values and the theoretical L_i subshell photoionisation cross sections, Coster–Kronig transition probabilities and emission rates. It is observed that the measured L_i subshell X-ray fluorescence cross section and L_i subshell fluorescence yield values for B = 0 are in good agreement with the theoretical ones evaluated using L_i subshell fluorescence yield and L_i subshell photoionization cross section. Furthermore, the results show that the atomic parameters such as spectral linewidth, radiation rates, photoionization cross section and fluorescence yield can change when the irradiation is conducted in a magnetic field.     

The mechanisms of photochromic transformations of 2-indolylfulgides

Photochromic properties of 2-indolylfulgides, namely, Z-3-[1-(1,3-dimethyl-1H-indol-2-yl)ethylidene]-4-isopropylidenetetrahydrofuran-2,5-dione andE-3-isopropylidene-4-(1-methyl-1H-indol-2-ylmethylidene)tetrahydrofuran-2,5-dione, were studied. The quantum yields of their photochemical isomerizations in toluene and the rate constant of the dark ring-opening in ethanol were determined. The fluorescence spectra of the open and cyclic forms of 2-indolylfulgides were measured. It was assumed that the excited-stateZ-isomer can be transformed into a cyclic isomer without intermediacy of anE-isomer in the ground state. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1026–1029, June, 2000.     

Excited state behaviour of pentahelicene dinitriles

The excited singlet and triplet states 2,13-dicyano[5]helicene (1) and two para-dicyno[5]helicenes containing one and two methyl groups (2 and 3, respectively) were studied in solvents of different polarity as a function of temperature. Fluorescence quenching by electron donors such as triethyl amine indicated photoinduced electron transfer. In the absence of additives triplet states were observed by flash photolysis. The triplet lifetime at room temperature was rather short (<1 μs) and the decay limited by intramolecular processes, e.g. charge transfer in the cases of 2 or 3. Luminescence of singlet molecular oxygen, O₂(¹Δ_g), was observed with moderate and low quantum yield for 1 and 3, respectively. For 1–3, the triplet lifetime increases by six orders of magnitude on going to −196°C. Two subsequently formed triplet states were observed for 3 at lower temperatures. The effects of temperature and solvent polarity on the quantum yields of fluorescence and phosphorescence and the spectroscopic and kinetic triplet absorption properties were examined. The influence of substituents on the deactivation pathways of excited pentahelicenes are discussed.