An Application of Multi-echelon Inventory System Theory to Management of Equipment Maintenance

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A Contribution to the Theory of Porosity of Fine‐Grained Sediments

The influence of adhesive forces on the structure of sedimentation layers has been considered. A theoretical model allowing calculation of the porosity of a sedimentation layer as a function of the particle size, the layer thickness, and the adhesiveforce level has been developed. Experiments in which these variables were changed have been carried out. The adhesive force was varied by changing the concentration of the electrolyte. A quantitative agreement between theory and experiment is observed for the porosity as a function of the particle size and the layer thickness; for the porosity as a function of the adhesive force this agreement is qualitative.     

Assessing and predicting the quality of research master’s theses: an application of scientometrics

Scientometrics - The educational quality of research master’s degree can be in part reflected by the examiner score of the thesis. This study focuses on finding positive predictors of this...     

Improved sensitivity of tunable far-infrared spectroscopy: application to the detection of HBr in the ? = 1 state

We report the first detection of the pure rotational spectra of H79 Br and H81 Br in the first excited vibrational state at room temperature. We recorded the spectra with a tunable far-infrared spectrometer equipped with an optimized Ge:Ga photodetector and an improved multiple-pass gas cell to enhance the overall sensitivity. In particular, a minimum detectable absorption of better than 10-7 cm-1 was achieved. We measured a total of 60 frequencies for the two isotopomers with an accuracy of a few parts in 108 . The hyperfine structure was observed at the lower J values. The derived spectroscopic parameters, which include nuclear and quadrupole hyperfine constants, reproduce the assigned transitions within their experimental errors.     

Determinants of consumers’ remanufactured products purchase intentions: Evidence from China

Previous studies have examined the main factors that influence consumer acceptance of remanufactured products based on the theory of planned behaviour (TPB). However, researchers have not yet conducted detailed studies to classify the variables of TPB. In the present research, this gap is addressed by using a TPB model which (1) differentiates attitude into experiential attitude and instrumental attitude, (2) differentiates subjective norm into normative social influence and informational social influence, and (3) differentiates perceived behavioural control into product knowledge, perceived risk, and perceived inconvenience. In this study, past experience and the interaction effect of attitude and subjective norm are also considered. The research results suggest that experiential and instrumental attitude, normative and informational social influence, product knowledge, and past experience are positive determinants of consumers’ purchase intentions toward remanufactured products, while perceived inconvenience and perceived risk are negative determinants. Furthermore, the findings also suggest that the interaction effects of experiential attitude and subjective norms positively affect purchase intentions, whereas the interaction effects of instrumental attitude and subjective norms have a negative effect. Based on the research conclusions, this study concludes with a discussion of proposals for improving consumers’ remanufactured product purchase intentions, implications for product design and manufacturing, limitations of the current study, and recommendations for further research.     

Identifying the competitive determinants of firms’ green supply chain capabilities under uncertainty

The link between green supply chain (GSC) and firm performance has been thoroughly studied, and it has been argued that firms are unlikely to perform well if they apply their capabilities in isolation. However, there is a lack of studies that identify the competitive determinants, the critical success factors, of GSC capabilities of firms, and the evaluation of GSC capabilities is predisposed to subjective and linguistic preferences. This study proposes to address the vague nature of qualitative measures using the fuzzy Delphi method to filter the measures and the fuzzy analytic network process to deal with the linguistic preferences in hierarchical structure of firms’ GSC capabilities. Data were collected from supply chain networks of electronic industry in Taiwan. This study presents empirical evidence of firms’ GSC capabilities, concluding that cost is the top competitive determinant and the environmental costs is the top priority of GSC capability.     

Electron–photon equation of motion with application to the Lamb shift

An equation of motion (EOM) is proposed for the electron which includes the effect of the radiation field on the electron's motion. The new EOM – the electron–photon EOM (EPEOM) – is the same as Dirac's equation with the ‘bare’ or mechanical mass replaced by a complex electromagnetic mass whose real part is interpreted as the observed mass of the electron. The Lamb shift is calculated from the difference of the EPEOM energy and the Dirac-equation energy.     

Reading between the lines of the ‘Responsible Resource Development’ rhetoric: the use of omnibus bills to ‘streamline’ Canadian environmental legislation

In Canada, the use of omnibus budget bills in recent years has grown substantially. In 2012, it was used twice by the Government of Canada. As a result, a number of substantial changes to environmental legislation were introduced with virtually no debate nor compromise. This situation has been criticized for seriously reducing the credibility of the budget process and the authority of Parliament in Canada, as well as undermining the transparency and accountability of the policy-making process. This paper describes how changes to major policies through the use of omnibus bills (all, arguably, in the name of faster project review decisions) affect not only established environmental protection efforts, but also the public and Aboriginal (First Nations, Inuit and Metis) peoples, particularly in terms of their capacity to effectively participate in resource development.     

Dynamics of Polymeric Fluids: Part II The Molecular Theory of Die Swell: Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

A general expression for the correlation of the simple shear (tan(?)) to the molecular parameters and the shear rate (γ) was deduced. It shows that the simple shear (tan(?)) may be resolved into free recoil (recoverable strain) and viscous heating (unrecoverable strain). The magnitudes of the simple shears for recoil (tan(?)E) and (tan(?)V) for viscous heating not only depended on the molecular parameters and the operational variables, but also on the exponential fractions of the recoverable (1-Wγ) and unrecoverable (W-γ) conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears (tan(?)E) for recoil and (tan(?)V) for viscous heating are, respectively, expressed as the partition function to the (1-Wγ)th power and the partition function to the (Wγ)th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n', a,η0, GN0 and (1-Wγ)] and the operational variables (γ, (L/D) and tr) were deduced respectively, which show that at very different shear rates (0≤γ≤∞) the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=(L/D)], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n', a,η0, GN0 and (1-Wγ)] and the operational variables (γ, (L/D) and tr) were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene (HDPE) which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.     

Dynamics of Polymeric Fluids: Part Ⅱ The Molecular Theory of Die Swell: Correlation of Ultimate Die Swelling Effect to the Molecular Parameters and the Operational Variables

A general expression for the correlation of the simple shear(tanφ)to the molecular parameters and the shear rate(γ)was deduced. It shows that the simple shear(tanφ)may be resolved into free recoil(recoverable strain)and viscous heating(unrecoverable strain). The magnitudes of the simple shears for recoil(tanφE)and(tanφv)for viscous heating not only depended on the molecular parameters and the operational variables,but also on the exponential fractions of the recoverable(1-(W)γ)and unrecoverable((W)γ)conformations for recoil and viscous heating. Therefore the magnitudes of the simple shears(tanφE)for recoil and(tanφv)for viscous heating are, respectively, expressed as the partition function to the(1-(W)γ)th power and the partition function to the(-(W)γ)th power. Thus correlations of the total recoil and the ultimately recoverable strains to the molecular parameters [n', a, η0, G0NN and(1--(W)γ)] and the operational variables(·γ, (L/D)and tr)were deduced respectively, which show that at very different shear rates(0≤·γ≤∞)the polymeric liquids may exhibit a very different viscoelastic behaviors. After introducing the uniform two-dimensional extension, the definition of swelling ratio and the ratio of L to D [De=(L/D)], two expressions for the ultimate die swelling effect and the ultimate extrudate swelling ratio BEVT5 to the molecular parameters [n', a, η0, G0N and(1--(W)·γ)] and the operational variables(·γ,(L/D)and tr)were obtained. The two correlation expressions were verified by the experimental data of high-density polyethylene (HDPE) which shows that the two correlation expressions can be used to predict the correlations of the ultimate extrudate swelling behaviors of polymeric liquids to the molecular parameters and the operational variables.     

Increasing the precision and accuracy of top-loading balances: application of experimental design

The traditional method of estimating the weight of multiple objects is to obtain the weight of each object individually. We demonstrate that the precision and accuracy of these estimates can be improved by using a weighing scheme in which multiple objects are simultaneously on the balance. The resulting system of linear equations is solved to yield the weight estimates for the objects. Precision and accuracy improvements can be made by using a weighing scheme without requiring any more weighings than the number of objects when a total of at least six objects are to be weighed. It is also necessary that multiple objects can be weighed with about the same precision as that obtained with a single object, and the scale bias remains relatively constant over the set of weighings. Simulated and empirical examples are given for a system of eight objects in which up to five objects can be weighed simultaneously. A modified Plackett-Burman weighing scheme yields a 25% improvement in precision over the traditional method and implicitly removes the scale bias from seven of the eight objects. Applications of this novel use of experimental design techniques are shown to have potential commercial importance for quality control methods that rely on the mass change rate of an object.     

Optimisation of the composition of an acrylic bone cement: application to relative amounts of the initiator and the activator/co-initiator in Surgical Simplex®P

In cemented arthroplasties, the two-part self-curing acrylic bone cement is currently the only material used for anchoring the total joint replacement to the contiguous bone. In virtually all commercially available formulations of this cement, the agents used for the initiation and activation/co-initiation of the radical polymerisation reaction are benzoyl peroxide (BPO) and N, N dimethyl-para-toluidine (DMPT), respectively. There are no reports in the open literature on the rationale for the amounts of these and other constituents in the formulations of the cement. Given the concerns that have been raised in the literature regarding the effect of residual DMPT on the body, it is important to keep the starting amounts of BPO and DMPT as high and as low, respectively, as possible. In the present work, the focus is on the relative amounts of these two agents in the case of one widely used commercial formulation, Surgical Simplex(R) P. Thirty variants of this cement were formulated, covering three concentrations of the co-polymer/BPO (75%, 80%, and 85% of the mass of the powder) and DMPT amounts (ranging from 0.8 %v/v to 2.4% v/v.) The setting time (t(set)), the peak temperature reached during the cement polymerisation process (T(max)), and the ultimate compressive strength (UCS) of each of the formulations were determined in accordance with procedures specified in ISO 5833. A critical examination of all the results indicated that the optimum ratio of the concentration of the initiator (BPO embedded in the PMMA-sytrene co-polymer) to that of the activator/co-initiator (DMPT) in Surgical Simplex(R) P is 57.14 (80%w/w co-polymer + BPO per 1.4%v/v DMPT). The mean values of t(set), T(max), and UCS of this optimum formulation were determined to be 12.30 min, 68 degrees C, and 101 MPa, respectively, all of which are within the limits specified in ISO 5833. The commercially available formulation of this cement contains 2.5%v/v DMPT, while the optimum formulation, as found in the present work, has 44% less DMPT, which may translate to a smaller amount of residual DMPT that is available for elution into the periprosthetic tissue in a cemented arthroplasty, over the in vivo life of the joint replacement.     

Letter to the editor: comments on the paper of Gagolewski et al.: Ockham’s index of citation impact

Scientometrics - In a recent paper in Scientometrics, Gagolewski et al. (2022) elaborated on a 3DSI model (3 dimensions of scientific impact) using a triplet of primary indicators (N, the number of...     

Compressible flow in a plate/plate rheometer: application to the experimental determination of reactive expansion’s models parameters for polyurethane foam

The quality of polyurethane foam’s structure mainly depends on the manufacturing process, during what two concomitant principal exothermic chemical reactions take place: the first one creates CO₂ dissolved into the fluid matrix (initiating micro-bubbles, expansion and coarsening of the foam) and the second one leads to the polymerization. In order to follow the rheological evolution of the PU foam during the process, the evolutions of the rheological properties of the foam during the process have been measured in a plate/plate rheometer with imposed deformation (RMS 800) and imposed stress (Stresstech). An analytical solution of the mechanical balance equation for viscoelastic compressible fluid has been proposed to describe the flow in this plate/plate rheometer with radial expansion. The trace of the elastic modulus G′ and the loss modulus G′′ as a function of time highlights the different steps of the foaming and polymerization process. The temperature dependence of both reactions follows Arrhenius’ laws. The recording of G′ and G′′ allows to identify kinetic parameters of numerical models for describing the expansion of a polymer foam and taking into account both chemical reactions.