Selecting between Sequential Zoning and Simultaneous Zoning for Picker-to-parts Order Picking System Based on Order Cluster and Genetic Algorithm

The existing research of sequential zoning system and simultaneous zoning system mainly focuses on some optimization problems such as workload balance,product assignment and simulation for each system separately.But there is little research on comparative study between sequential zoning and simultaneous zoning.In order to help the designers to choose the suitable zoning policy for picker-to-parts system reasonably and quickly,a systemic selection method is presented.Essentially,both zoning and batching are order clustering,so the customer order sheet can be divided into many unit grids.After the time formulation in one-dimensional unit was defined,the time models for each zoning policy in two-dimensional space were established using filling curves and sequence models to link the one-dimensional unit grids.In consideration of U shaped dual tour into consideration,the subtraction value of order picking time between sequential zoning and simultaneous zoning was defined as the objective function to select the suitable zoning policy based on time models.As it is convergent enough,genetic algorithm is adopted to find the optimal value of order picking time.In the experimental study,5 different kinds of order/stock keeping unit(SKU) matrices with different densities d and quantities q following uniform distribution were created in order to test the suitability of sequential zoning and simultaneous zoning to different kinds of orders.After parameters setting,experimental orders inputting and iterative computations,the optimal order picking time for each zoning policy was gotten.By observing whether the delta time between them is greater than 0 or not,the suitability of zoning policies for picker-to-parts system were obtained.The significant effect of batch size b,zone number z and density d on suitability was also found by experimental study.The proposed research provides a new method for selection between sequential zoning and simultaneous zoning for picker-to-parts system,and improves the rationality and efficiency of selection process in practical design.     

The polymerization of propargyl halides (Cl,Br) using M(CO)5PPh3/R x AlCl3-x (M=Mo,W) as catalysts

Summary Propargylchloride (PCl) and propargylbromide (PBr) were polymerized in good yields using M(CO)₅PPh₃/R_xAlCl_3-x as catalysts (M=W, Mo). Mo was found to be more effective than W. The presence of chlorine atoms in co-catalyst was important for the activation of the catalyst. The obtained polymers were coloured, insoluble in all organic solvents and stable until 150°C. From their IR and ESR spectra is concluded that the polymers have highly conjugated structures. The oligomeric products were constituted mainly from cyclotrimers. In the case of Mo-catalyst only 1,2,4-cyclotrimer was obtained; a mixure of 1,2,4 and 1,3,5-derivatives were formed using W-catalysts.     

State of the Art Treatment of Non-Ferrous Castings 3-in-l Heat Treatment Systems Combine Foundry Processes

1.Aluminum Casting Production Now andThenIt is well known that the reduction of the total weightof an automobile leads to a reduction in fuelconsumption(about0.5liters of100kilometers).Thisimproved fuel economy also reduces the CO2emissionsreleased into the atmosphere.As the size of vehicleshas grown,the overall weight has had to be decreased.The automotive industry is therefore using more andlighter metal components in order to reduce fuelconsumption and lower emissions.Production of cylin…     

Telephone counseling for smoking cessation: Effects of single-session and multiple-session interventions.

Smokers (N?=?3,030) were randomized to receive 1 of 3 interventions: (a) a self-help quit kit, (b) a quit kit plus 1 telephone counseling session, or (c) a quit kit plus up to 6 telephone counseling sessions, scheduled according to relapse probability. Both counseling groups achieved significantly higher abstinence rates than the self-help group. The rates for having quit for at least 12 months by intention to treat were 5.4% for self-help, 7.5% for single counseling, and 9.9% for multiple counseling. The 12-month continuous abstinence rates for those who made a quit attempt were 14.7% for self-help, 19.8% for single counseling, and 26.7% for multiple counseling. A dose–response relation was observed, as multiple sessions produced significantly higher abstinence rates than a single session. The first week after quitting seems to be the critical period for intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relationship between long-term job strain and morning and evening saliva cortisol secretion among white-collar workers.

The objective of this study was to assess long-term job strain impact on morning and evening salivary cortisol secretion. In all 77 white-collar workers (31% women; sample mean age, 42 years at baseline) volunteered to sample morning (immediately after waking up) and evening (10 p.m.) salivary cortisol for 7 consecutive days. By median split on aggregated self-reported isostrain from three consecutive questionnaires distributed in a period of approximately 3.5 years the participants were classified into a high or low long-term isostrain condition. Regardless of strain condition, there was a significant reduction in morning salivary cortisol secretion from the working week to the weekend, whereas evening salivary cortisol secretion showed no significant variation during the week. Although chronic isostrain did not affect the morning saliva cortisol measures, evening cortisol secretion was significantly elevated in the chronic high isostrain group throughout the whole week. The elevated evening cortisol measures associated with chronic high strain are concordant with the findings in other studies on long-term strain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Current Advances in 3D Tissue and Organ Reconstruction

Bi-dimensional culture systems have represented the most used method to study cell biology outside the body for over a century. Although they convey useful information, such systems may lose tissue-specific architecture, biomechanical effectors, and biochemical cues deriving from the native extracellular matrix, with significant alterations in several cellular functions and processes. Notably, the introduction of three-dimensional (3D) platforms that are able to re-create in vitro the structures of the native tissue, have overcome some of these issues, since they better mimic the in vivo milieu and reduce the gap between the cell culture ambient and the tissue environment. 3D culture systems are currently used in a broad range of studies, from cancer and stem cell biology, to drug testing and discovery. Here, we describe the mechanisms used by cells to perceive and respond to biomechanical cues and the main signaling pathways involved. We provide an overall perspective of the most recent 3D technologies. Given the breadth of the subject, we concentrate on the use of hydrogels, bioreactors, 3D printing and bioprinting, nanofiber-based scaffolds, and preparation of a decellularized bio-matrix. In addition, we report the possibility to combine the use of 3D cultures with functionalized nanoparticles to obtain highly predictive in vitro models for use in the nanomedicine field.     

Modelling and analysis of the oxidation influence on creep behaviour of thin-walled structures of the single-crystal nickel-base superalloy René N5 at 980 °C

Creep test results of thin-walled specimens of the single-crystal nickel-base superalloy René N5 at 980 °C under vacuum as well as under air show different creep properties depending on material thickness and atmosphere. The differences in creep strength and strain were analysed based on a creep-oxidation model. The model specifies the primary and secondary creep stages of thin-walled specimens by a sequence of layers. The model takes different zones affected by oxidation into account. Four layers were experimentally observed and considered in the model: oxide layer, γ′-free layer, γ′-reduced layer and the two-phase substrate in the sample as centre. Material parameters for growth laws of each layer were identified both by experimental analyses and by thermodynamic simulations. The final creep-oxidation model characterizes the creep behaviour of samples with small thicknesses and low initial stress with high accuracy.     

Tuning the Mechanical Properties of BIEE‐Crosslinked Semi‐Interpenetrating,Double‐Hydrophilic Hydrogels

Double‐hydrophilic, semi‐interpenetrating (semi‐IPN) hydrogels are synthesized by encapsulating hydrophilic polyvinylpyrrolidone (PVP) linear chains in structure‐defined 1,2‐bis‐(2‐iodoethoxy)ethane (BIEE)‐crosslinked (poly(2‐(dimethylamino)ethyl methacrylate) (pDMAEMA) hydrogels. A series of semi‐IPN double‐hydrophilic hydrogels are prepared in which the pDMAEMA/BIEE content is kept the same and only the PVP content is varied, from 0 up to 33 wt%. The mechanical properties of the water‐swollen hydrogels are experimentally evaluated under unconfined compressive loading conditions, while a nonlinear hyperelastic constitutive equation is used to predict their mechanical response. No significant difference is found in the mechanical response of the semi‐IPN PVP/pDMAEMA/BIEE hydrogel containing 5 wt% PVP compared to the pDMAEMA/BIEE analog, however, for greater loading percentages (15 and 33 wt% of PVP), the semi‐IPN hydrogels exhibit less stiffness/higher ductility. Furthermore, in vitro biocompatibility studies are carried out for the pDMAEMA/BIEE and the semi‐IPN PVP/pDMAEMA/BIEE, indicating that both the formulations exhibit no toxicity in cultured cells.