A joint replenishment policy with individual control and constant size orders

We consider inventory systems with multiple items under stochastic demand and jointly incurred order setup costs. The problem is to determine the replenishment policy that minimises the total expected ordering, inventory holding, and backordering costs–the so-called stochastic joint replenishment problem. In particular, we study the settings in which order setup costs reflect the transportation costs and have a step-wise cost structure, each step corresponding to an additional transportation vehicle. For this setting, we propose a new policy that we call the (s, 𝒬) policy, under which a replenishment order of constant size 𝒬 is triggered whenever the inventory position of one of the items drops to its reorder point s. The replenishment order is allocated to multiple items so that the inventory positions are equalised as much as possible. The policy is designed for settings in which backorder and setup costs are high, as it allows the items to independently trigger replenishment orders and fully exploits the economies of scale by consistently ordering the same quantity. A numerical study is conducted to show that the proposed (s, 𝒬) policy outperforms the well-known (𝒬, S) policy when backorder costs are high and lead times are small.     

Effects of water extract of Urtica dioica L. and modified atmosphere packaging on the shelf life of ground beef

Effects of lyophilized Urtica dioica L. water extract (LUWE) and modified atmosphere packaging (MAP) on the quality and shelf life of ground beef were investigated. Ground beef was stored as aerobic control, MAP (80%O₂ + 20% CO₂), MAP + 250 ppm LUWE and MAP and 500 ppm LUWE at 2 ± 0.5 °C for 14 days. MAP and LUWE had significant effects on mesophilic, psychrotrophic and lactic acid bacteria and Pseudomonas counts. Depending on the level of LUWE, Pseudomonas and psychrotrophic counts decreased. Treatment with 500 ppm LUWE + MAP showed the lowest TBARS values compared to other groups during storage. 80% O₂-MAP increased TBARS values. Treatment had no significant effect on L* and b* values of the exterior of the ground beef, but had significant effects on the color of interior sections.     

Patient‐specific phosphorus mobilization clearance during nocturnal and short daily hemodialysis

The kinetics of plasma phosphorus during different hemodialysis (HD) modalities are incompletely understood. We recently demonstrated that a pseudo one‐compartment kinetic model including phosphorus mobilization from various body compartments into extracellular fluids can describe intradialytic and postdialytic rebound kinetics of plasma phosphorus during conventional and short 2‐hour HD treatments. In this model, individual patient differences in phosphorus kinetics were characterized by a single parameter, the phosphorus mobilization clearance (K_M). In this report we determined K_M in patients treated by in‐center nocturnal HD (ICNHD) and short daily HD (SDHD) with low dialyzer phosphate clearance. In the ICNHD study, eight patients underwent 8‐hour HD treatments where intradialytic and postdialytic plasma samples were collected; K_M values were determined by nonlinear regression of plasma concentration as a function of time. In the SDHD study, five patients were studied during 28 treatments for approximately 3 hours. Here, K_M was calculated using only predialytic and postdialytic plasma phosphorus concentrations. Dialyzer phosphate clearances were 134 ± 20 (mean ± SD) and 95 ± 16 mL/min during ICNHD and SDHD, respectively. K_M values for the respective therapies were 124 ± 83 and 103 ± 33 mL/min, comparable to those determined previously during conventional and short HD treatments of 98 ± 44 mL/min. When results from ICNHD, SDHD, and previous HD modalities were combined, K_M was directly correlated with postdialytic body weight (r = 0.38, P = 0.025) and inversely correlated with predialytic phosphorus concentration (r = ?0.47, P = 0.005). These findings suggest that phosphorus kinetics during various HD modalities can be described by a pseudo one‐compartment model.     

EXTRACTION OF TITANIUM(IV) FROM AQUEOUS HYDROCHLORIC ACID SOLUTIONS INTO ALAMINE 336-M-XYLENE MIXTURES

Extraction of Ti(IV) from its aqueous hydrochloric acid solutions into organic Alamine 336-m-xylene systems was investigated. Extraction experiments were conducted with three different initial metal concentrations of 1, 3, and 6 mg/mL, each at three acidic molarities of 1, 5, and 10 M. It was observed that the extractability of Ti(IV) increases with increasing acidic molarities. Alamine 336 diluted with m-xylene was found to be a suitable extractant for Ti(IV) across this acidic range. In parallel, a mathematical model was developed to correlate metal extractability and Alamine 336 volume content. Optimal Alamine 336 contents were estimated for single-stage extraction.     

Comparison of Turkey's performance of greenhouse gas emissions and local/regional pollutants with EU countries

Turkey signed the Kyoto Protocol on February 17th, 2009. Therefore, to fulfill the liabilities of the Kyoto Protocol, she has to review her status and make strategic plans to hold the emissions at the levels specified in the protocol. For this purpose, in this study employing data envelopment analysis (DEA), Turkey's greenhouse gas (GHG) emissions and local/regional pollutants compared to the European Union (EU) countries have been put in place. Since the data on Malta and Cyprus was inadequate, these two nations were excluded from the evaluation. As a candidate for EU, Turkey is required to reduce the emissions by 8% until 2012 within the framework of the Kyoto Protocol.     

Flexural Behavior of GFRP-Reinforced Concrete Masonry Beams

An experimental and analytical study is conducted in order to investigate the flexural behavior of masonry beams that are internally reinforced using glass fiber-reinforced polymers (GFRP) rebars. Seven reinforced masonry beams with 4.0- and 2.4-m spans were tested under four-point bending setup. The beams were loaded monotonically up to failure. One had two courses of hollow concrete masonry units and the remaining six beams had three courses. Two masonry beams were reinforced using conventional steel rebars and were considered as the control specimens. The remaining five beams were internally reinforced using GFRP rods with different reinforcement ratios. Beams were detailed to have sufficient shear reinforcement such that they do not fail in shear. Flexural capacity, deformation, curvature, and strains of the tested GFRP-reinforced and steel-reinforced masonry beams were compared and discussed. Using the acquired data from the experimental and analytical studies, effectiveness of GFRP rods as internal reinforcement for concrete masonry beams is demonstrated.     

Comparison of the usage of nut shell,walnut shell,and pistachio shell as a reinforcement particle on the mechanical and wear performance of polypropylene

In this study, the usability of nutshell, pistachio, and walnut shell wastes as reinforcement materials in industrial applications and their comparisons with each other was examined. For this purpose, composite samples with a polypropylene (PP) matrix were produced and their mechanical and tribological characterizations were performed. As a result of the tensile tests, both the tensile strength and elastic modulus values of all composite specimens are higher than those of pure PP. On the other hand, the value of elongation at break is lower. The sliding wear resistance increases with increasing reinforcement with walnut and pistachio shell reinforcement, whereas the positive effect becomes negative when the nutshell reinforcement is over 3 wt%. All three types of reinforcement positively affected the scratch resistance. Pistachio shell reinforcement gives the best result. It has been determined that the relative cutting volume value of the samples increases with the reinforcement rate and the wear behavior changes from ductile to brittle. In light of these results, it has been seen that nut, pistachio, and walnut shells could be used as reinforcement materials in industrial applications instead of being waste or fuel.     

Time–frequency analysis of signals using support adaptive Hermite–Gaussian expansions

Since Hermite–Gaussian (HG) functions provide an orthonormal basis with the most compact time–frequency supports (TFSs), they are ideally suited for time–frequency component analysis of finite energy signals. For a signal component whose TFS tightly fits into a circular region around the origin, HG function expansion provides optimal representation by using the fewest number of basis functions. However, for signal components whose TFS has a non-circular shape away from the origin, straight forward expansions require excessively large number of HGs resulting to noise fitting. Furthermore, for closely spaced signal components with non-circular TFSs, direct application of HG expansion cannot provide reliable estimates to the individual signal components. To alleviate these problems, by using expectation maximization (EM) iterations, we propose a fully automated pre-processing technique which identifies and transforms TFSs of individual signal components to circular regions centered around the origin so that reliable signal estimates for the signal components can be obtained. The HG expansion order for each signal component is determined by using a robust estimation technique. Then, the estimated components are post-processed to transform their TFSs back to their original positions. The proposed technique can be used to analyze signals with overlapping components as long as the overlapped supports of the components have an area smaller than the effective support of a Gaussian atom which has the smallest time-bandwidth product. It is shown that if the area of the overlap region is larger than this threshold, the components cannot be uniquely identified. Obtained results on the synthetic and real signals demonstrate the effectiveness for the proposed time–frequency analysis technique under severe noise cases.     

Engineering MIL-88B crystallites for enhanced H2 uptake capacity: The role of ultramicropores

In this study, a strategy that optimizes the pore size to enhance the adsorbed H₂ amount (at 298 K) is investigated. Pore size and ultramicropore fraction (ultramicropore volume/total pore volume) were controlled by Fe:TPA ratio. The highest H₂ adsorption capacity of 0.47 wt% (298 K and 7.6 bar) belongs to MIL-88B-3, which is higher than those of reported metal-organic frameworks (MOFs) (MIL-100, MIL-101 [Cr], HKUST-1, MOF-5, and ZIF-8). The enhanced H₂ sorption capacity (1.96 times) is a consequence of the high fraction (89%) and volume (0.22 cm³/g) of ultramicropores with pore diameters of 0.6 nm. Our results demonstrate that pore size, fraction, and volume of ultramicropores control the amount of H₂ adsorbed also at 298 K. With the use of perturbation assisted nanofusion synthesis strategy that introduces textural pores to the pore structure, a Brunauer-Emmett-Teller (BET) surface area higher than those of reported MIL-88Bs has been achieved, and a strategy to synthesize MOFs with enhanced H₂ sorption capacities is suggested.