Economic profit of machining is essentially based on the optimal selection of cutting parameters. In this paper, a multi-objective particle swarm optimization approach is introduced to optimize the cutting parameters in turning processes: cutting speed, feed rate and cutting depth. The proposed model presents the problem in form of a multi-objective problem with production rate and used tool life objectives and has a set of constraints that represent the important limitations to be satisfied. To obtain the non dominated solutions and build the Pareto front graph, a modified dynamic neighborhood particle swarm optimization (DNPSO) technique is used. In addition, a fuzzy-based mechanism is employed to extract the best compromise solution. The results on an illustrative sample reveal the capabilities of the proposed DNPSO approach to generate well-distributed Pareto optimal solutions. Comparison with multi-objective deterministic approach (Min?CMax) shows the superiority of the proposed approach and confirms its potential for solving multi-objective problems. 相似文献
This paper presents a new and innovative methodology for power components manufacturers to generate accurate boundary condition independent dynamic Compact Thermal Models (“BCI” DCTMs). The originality of this methodology is summarized by taking into account the thermal behavior of electronic components containing several cooling surfaces, and representing the non-linear properties of materials, while keeping a simple and recurring structure of generated models. Moreover, the proposed method makes it possible to obtain DCTMs with a limited number of measurements or 3D thermal simulations. The methodology to construct the DCTM is based on the construction of an equivalent thermal RC network. The precision of the RC thermal network is improved using variable resistances and capacitances related to the heat fluxes so that the compact model can adapt automatically with boundary conditions. 相似文献
Engineering with Computers - Fractal–fractional differential and integral operators have been recognized recently as superior operators as they are able to depict physical problem with both... 相似文献
There is considerable preclinical evidence for a relationship between noradrenergic brain systems and behaviors associated with stress and anxiety. The majority of noradrenergic neurons are located in the locus coeruleus (pons), with projections throughout the cerebral cortex and multiple subcortical areas, including hippocampus, amygdala, thalamus, and hypothalamus. This neuroanatomical formation of the noradrenergic system makes it well suited to rapidly and globally modulate brain function in response to changes in the environment, as occurs during the presentation of stressors. Stress exposure is associated with an increase in firing of the locus coeruleus and with associated increased release and turnover of norepinephrine in brain regions which receive noradrenergic innervation. Increased firing of the locus coeruleus is also associated with behavioral manifestations of fear, such as arched back and piloerection in the cat. Exposure to chronic stress results in long-term alterations in locus coeruleus firing and norepinephrine release in target brain regions of the locus coeruleus. Norepinephrine is also involved in neural mechanisms such as sensitization and fear conditioning, which are associated with stress. These findings are relevant to an understanding of psychiatric disorders, such as panic disorder and post-traumatic stress disorder (PTSD), the symptoms of which have been hypothesized to be related to alterations in noradrenergic function. 相似文献
Ochratoxin A (OTA), a nephrotoxic mycotoxin probably implicated in human Balkan endemic nephropathy and associated urothelial tumors, induces renal carcinomas in rodents and nephrotoxicity in pigs. OTA induces DNA-adduct formation, but the structure of the adducts and their role in nephrotoxicity and carcinogenicity have only partly been elucidated. In vivo, 2-mercaptoethane sulfonate (MESNA) protects rats against OTA-induced nephrotoxicity but not against carcinogenicity, indicating two different mechanisms leading to nephrotoxicity or carcinogenicity. To better understand how DNA-adduct could be generated, opossum kidney cells (OK) have been treated by OTA alone or in presence of several compounds such as MESNA or N-acetylcysteine (another agent that, like MESNA, reduces oxidative stress by increasing of free thiols in kidney), buthionine sulfoximine (BSO) (an inhibitor of glutathione-synthase), and alpha amino-3-chloro-4,5-dihydro-5-isoxazole acetic acid (ACIVICIN) (an inhibitor of gamma glutamyl transpeptidase). Cytotoxicity of OTA on OK cells was evaluated by applying the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. None of the listed agents diminished OTA cytotoxicity significantly; ACIVICIN even increases OTA cytotoxicity. In contrast, analysis of the HPLC profiles of OTA metabolites produced during these incubations indicated that the pattern, the quantity of metabolites, and the nature of the derivatives were modulated by these agents. Ochratoxin B (OTB), open-ring ochratoxin A (OP-OA), 4 hydroxylated OTA, 10 hydroxylated OTA, OTA without phenylalanine, OTB without phenylalanine, and a dechlorinated OTA metabolite could be identified by nano-ESI-IT-MS. 相似文献
Silicon - In recent years, silicon-organic hybrid solar cells have attracted tremendous research attention owing to their low production cost and high performance. In the present work, tapered... 相似文献
Silicon - In the last few years, an accelerated trend towards the miniaturization of nanoscale circuits has been recorded. In this context, the Tunneling Field-Effect Transistors (TFETs) are... 相似文献
Novel green-emitting phosphors K2Zn1???xP2O7: x mol% Mn2+ have been successfully prepared using classical solid-state reaction method in air atmosphere, doped by different Mn2+ ion contents, namely x?=?0.5, 1, 1.25 and 1.5 mol%. The samples were characterized by the thermogravimetric (ATD/ATG/DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), steady and time-resolved photoluminescence techniques. It was found that all K2Zn1???xP2O7: x mol% Mn2+ samples crystallize in the tetragonal phase with P42/mnm space group. Upon 425 nm excitation, K2ZnP2O7: Mn2+ exhibits an intense broad green asymmetric emission band peaking at 520 nm, owing to the 4T1→6A1(6 S) transition of Mn2+ ion in K2ZnP2O7. In addition, it is suggested that Mn2+ ions occupy more than one symmetry site in the host K2ZnP2O7. The optimal Mn2+ ion concentration in K2ZnP2O7:Mn2+ phosphor is 1 mol % and with the lifetime 9.81 ms.