The enzymic hydrolysis of commercial wheat starch and freshly prepared wheat starch fractions was studied in batch and flow systems. Fresh starch was prepared by wet separation of wheat flour into starch milk and gluten, followed by processing the starch milk using a serially connected hydrocyclone system to produce underflow and overflow streams. The underflow stream consisted mainly of the larger (> 30 w m) granules, while the overflow stream contained only the smaller (< 10 w m) granules. In batch system, the hydrolysis behavior of wheat starch fractions was investigated under the action of Sigma f -amylase ( Bacillus licheniformis ), either as soon as they were prepared or after spray drying. The two fractions of fresh wheat starch showed different hydrolysis behavior, the difference getting larger as the separation improves. Underflow streams were found to be much more susceptible to hydrolysis than overflow streams, regardless of whether the hydrolysis was carried out right away or on dried samples, and also regardless of whether rinsing was applied. In flow system, dried underflow stream and commercialwheat starch were hydrolyzed using Orbamil-T ( Bacillus licheniformis ), Orbamil-BHT ( Bacillus stearothermophilus ), and Sigma f -amylase ( Bacillus licheniformis ). Hydrolysis of fresh starch was found to be significantly faster than commercial wheat starch. Commercial f -amylase Orbamil-T was found to be almost as effective as the purified Sigma f -amylase. 相似文献
Dual phase steel has become an important engineering material to be used in structural and automotive applications due to its good combination of strength, ductility, and formability. In this study, hardenability of a low carbon and microalloyed steel was investigated by using the standard Jominy End Quench Test at four different quenching temperatures. Three steel specimens were quenched from the intercritical region at 737°C, 754°C, and 779°C separately, whereas one of them was tested at 900°C, in the fully austenitic region. After finishing the Jominy test, metallographic examination of the samples was carried out to see the variation in the microstructure through the length of the steel. And also, hardness measurements were made through the length of the samples. Results brought out that there was a strong decrease in the hardness of the tested samples after a depth of 5 mm from the quenched end. 相似文献
In this paper, a valuation approach that modifies traditional discounted cash flow (DCF) methodology is presented to incorporate the option premium of expansion flexibility while evaluating a flexible manufacturing system investment. Expansion flexibility allows for changing the production capacity in response to deviations in demand, while disregarding the assumption that management makes an irrevocable decision based on its future market expectations. Expansion flexibility provides a key strategic advantage by avoiding the large financial commitment at the initial investment stage and enabling investment in a phased manner according to the changes in market conditions. The aim of this paper is to present a thorough valuation methodology that accounts for both the benefits of keeping the option to expand alive and the loss of market share to competing firms if the expansion investment were delayed. In this paper, the value of expansion flexibility is computed using sequential exchange options. The proposed method employs an analytic approximation scheme for valuing American exchange options on dividend-paying assets. A numerical example demonstrates the application of the valuation framework. The options approach that incorporates the expansion flexibility option into the analysis results in a higher value than the standard DCF approach, which ignores the value of the option to expand. We also perform sensitivity analyses to see whether the expansion option increases in value in cases of high uncertainty where management can respond flexibly to new market information, and where the investment analysis ignoring flexibility yields a marginally positive net present value. The results of the proposed valuation framework are presented in comparison with a previous model that ignores the opportunity cost of delaying expansion investment. 相似文献
We evaluated the suitability, contribution to the national economy, and environmental impact of hydrocyclone and Multi-Gravity Separation (MGS) processes using fine-sized coal taken from the Soma coal sludge pond. The lignite coal tailings were treated by a two-stage concentration scheme for the recovery of fine clean coal. Pre-enrichment experiment parameters were determined by the Taguchi experimental design method, and the results were interpreted by the Statistical Packages for the Social Sciences (SPSS) 15.0 program to evaluate the optimum parameter values. The tailings initially contained 54.82% ash and had a LCV of 2,279 kcal/kg; after hydrocyclone pre-enrichment, the concentrate was 42.60% ash and had a calorific value of 2,573 kcal/kg (55.75% coal yield). After the final enrichment process, the ash of the pre-concentrated coal was decreased to 24.21% and left a clean coal with a base calorific value of 3,226 kcal/kg (36.16% coal yield). The total sulfur of the obtained clean coal was 0.52% and the combustible sulfur rate was 0.10%. To reduce the ash content of the obtained clean coal, a decantation process was performed that decreased the ash content to 21.84% and the base calorific value was increased to 4,109 kcal/kg. 相似文献
Nowadays healthcare organizations globally recognize the importance of investing in information technologies to improve the quality of care delivery and reduce costs. The key drivers of healthcare sector such as continuously improving healthcare standards and insurance systems have introduced new requirements for hospitals, which in return provided a solid ground for decision-makers to consider implementing hospital information systems that are customized and improved versions of enterprise resource planning (ERP) systems designed according to the needs of the healthcare sector. The conventional discounted cash flow methods ignore the value of managerial and strategic flexibility inherent in these investments, which is crucial for justification of the investment decision. This study introduces a real options-based methodology which overcomes the limitations of traditional valuation methods and enables decision-makers to value an ERP system investment incorporating multiple options. The option valuation model developed in this study extends the binomial lattice framework to model a hospital information system (HIS) investment opportunity with compound options. The potential application of the proposed model is illustrated through evaluation of a real-world HIS investment. 相似文献
In this paper, radiation characteristics of H-plane sectoral horn antenna are treated systematically by investigation of main structural design parameters and, flare edge rolling, throat bending and asymmetric flare effects. The analytical regularization method (ARM) is used to solve the problem of E-polarized wave diffraction in a fast and accurate way. The numerical procedure is initially verified by the analytical solutions, and then the calculated directivity gain patterns are demonstrated for the modeled horn antenna configurations. Proper choices of the antenna parameters, such as horn depth, aperture length, feeder waveguide width, flare angle, wall thickness, flare edge rolling and throat bending are proposed for the designers to reach high directivity gain, narrow beam width, suppressed side lobe levels, increased front-to back ratio and improved aperture efficiency. 相似文献
Four mixed-ligand coordination polymers, namely, [Zn(μ-3,3′-Cl2abdc)(μ-4,4′-azobpy)]n (1), [Zn(μ-4,4′-Cl2abdc)(μ-3,3′-azobpy)0.5(H2O)]n (2), [Zn2(μ-4,4′-Cl2abdc)(μ4-4,4′-Cl2abdc)0.5(μ-OH)(μ-4,4′-azobpy)]n (3) and {[Zn(H2O)4(μ-4,4′-azobpy)](4,4’-Cl2abdc)}n (4) (Cl2abdc: dichloroazobenzenedicarboxylate and azobpy: azobispyridine) were synthesized with azo-group containing positional isomer anionic and neutral ligands in the presence of Zn(II) ion and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction. X-ray results showed that the compounds displayed structural diversity depending on disposition of donor groups on ligands and solvent. Compounds 1 and 2 exhibited two-fold and five-fold interpenetrated 2D?→?2D structures, respectively, with the interchanging of positional isomer anionic and neutral ligands. Five-fold polycatenated 2D?→?3D structure was observed with the selection of 4,4′-Cl2abdc and 4,4′-azobpy in 3. Although same ligands were used in the synthesis of 4 like compound 3, 1D structure of 4 was obtained with the use of DMF:water mixture and zinc nitrate. 4,4′-Cl2abdc acted as a counter-ion in 4. Furthermore, topologic, thermal, optical and photoluminescence spectra of the compounds were studied in detail.
This study was performed to expand the usage area of phenylene sulfide (PSS) by reducing its cost without deteriorating the material properties. For this purpose, mechanical, thermo-mechanical and abrasion tests were conducted to composite materials obtained by adding carbon fiber (CF), basalt fiber (BF), zeolite, and bentonite into PPS, and the effects of additive type and ratio were examined. For the test samples, fabricated by the melt blending, the fiber content was 10 wt.%, while zeolite, and bentonite ratios were 1, 5, and 10 wt.%. According to tensile and abrasion test results, zeolite, and bentonite improved the properties of fiber-reinforced PPS by showing a synergistic effect. It has been demonstrated in this research that the cost of fiber-reinforced PPS matrix composites, which are widely used in advanced engineering applications, can be reduced by using natural minerals zeolite and bentonite without sacrificing material properties. Findings obtained from mechanical and wear tests, revealed that the composition containing 10, 10, and 80 wt.%, zeolite, CF, and PPS, respectively, exhibited optimum material properties. BF for PPS has been shown to be an alternative reinforcement to CF, as it exhibits the lowest wear rate and better interacts with particles in the matrix. 相似文献