Integrating Preventive Maintenance Scheduling as Probability Machine Failure and Batch Production Scheduling

This paper discusses integrated model of batch production scheduling and machine maintenance scheduling. Batch production scheduling uses minimize total actual flow time criteria and machine maintenance scheduling uses the probability of machine failure based on Weibull distribution. The model assumed no nonconforming parts in a planning horizon. The model shows an increase in the number of the batch (length of production run) up to a certain limit will minimize the total actual flow time. Meanwhile, an increase in the length of production run will implicate an increase in the number of PM. An example was given to show how the model and algorithm work

Discussion of “effect of exercise-induced dehydration on circulatory markers of oxidative damage and antioxidant capacity”

We read with great interest a recent article by Georgescu et al. (2017) entitled “Effect of exercise-induced dehydration on circulatory markers of oxidative damage and antioxidant capacity”. The authors aimed to investigate effects of hydration and rehydration by using sensitive indirect measures of oxidative stress and the antioxidant capacity response. In this study, they evaluated concentrations of plasma osmolality, Trolax equivalent antioxidant capacity (TEAC), and ferric reducing ability of plasma (FRAP) in a sample of athletes during pre-exercise, immediately postexercise, and 1 h after full rehydration. As stated in statistical analysis and also abstract of the article, the authors used 1-way ANOVA to compare differences in means of numerical variables (i.e., concentrations of plasma osmolality, TEAC, and FRAP) of different time-points of measurement. Since they investigated the same sample of participants in each group during different time-points (i.e., pre-exercise, immediately postexercise, and 1 h after full rehydration), their measurements are completely dependent (Farrokhi and Peykanpour 2017a; Farrokhi and Shirian 2017; Farrokhi et al. 2017). ANOVA and Kruskal–Wallis test are used for comparison of the means of more than 2 independent groups (Gaddis 1998; Farrokhi 2017b; Farrokhi and Arjaki 2017; Farrokhi and Peykanpour 2017b). Therefore, after assessment of the normal distribution of studied quantitative variables, including concentrations of plasma osmolality, TEAC, and FRAP, the authors must use repeated-measures ANOVA or Friedman test for comparison of the means of each variable at pre-exercise, immediately postexercise, and 1 h after full rehydration (Farrokhi 2017a; Farrokhi and Amani-Beni 2017). Furthermore, they must use Wilcoxon test and paired t test for comparison of concentrations of plasma osmolality, TEAC, and FRAP between 2 time-points of measurement

3D printing of PEEK-based medical devices

open access articlePolyether-ether-ketone (PEEK) is an excellent thermoplastic alternative to metallic biomaterials which is used for loadbearing applications due to its high strength and stiffness, and biocompatibility with no cytotoxic effects. However, a potential clinical concern is that PEEK alone is not bioactive enough, and thus has limited fixation to bone. To overcome this problem, bioactive materials and/or porosity are incorporated into PEEK medical devices. The latest developments in these two strategies are presented. in this paper. Bioactive PEEK/hydroxyapatite (HA) prepared by integration of 3D printing and compression molding is presented in this paper. In addition, nozzle and build plate temperatures for 3D printing of porous PEEK were optimized using genetic algorithm (GA) to achieve the highest mechanical strength for load bearing applications such as spinal fusion cages

Source Coding in Networks with Covariance Distortion Constraints

We consider a source coding problem with a network scenario in mind, and formulate it as a remote vector Gaussian Wyner-Ziv problem under covariance matrix distortions. We define a notion of minimum for two positive-definite matrices based on which we derive an explicit formula for the rate-distortion function (RDF). We then study the special cases and applications of this result. We show that two well-studied source coding problems, i.e. remote vector Gaussian Wyner-Ziv problems with mean-squared error and mutual information constraints are in fact special cases of our results. Finally, we apply our results to a joint source coding and denoising problem. We consider a network with a centralized topology and a given weighted sum-rate constraint, where the received signals at the center are to be fused to maximize the output SNR while enforcing no linear distortion. We show that one can design the distortion matrices at the nodes in order to maximize the output SNR at the fusion center. We thereby bridge between denoising and source coding within this setup

THE EFFECTS OF INDUSTRY STRUCTURE ON PRICE: A CASE IN THE BEEF INDUSTRY

This study estimates the influence of concentration and other structural variables on the price of slaughter cattle. Cross-sectional data were used to estimate a single equation model which included, in addition to traditional factor demand variables, packer concentration and a measure of market power exerted by feedlots. Results suggest that packer concentration has had a significant and increasing negative impact on fed cattle prices during the years of analysis, 1972 and 1977.Industrial Organization, Livestock Production/Industries,

Modeling of autoresonant control of a parametrically excited screen machine

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Modelling of nonlinear dynamic response of a screen machine described by the nonlinear coupled differential equations and excited by the system of autoresonant control is presented. The displacement signal of the screen is fed to the screen excitation directly by means of positive feedback. Negative feedback is used to fix the level of screen amplitude response within the expected range. The screen is anticipated to vibrate with a parametric resonance and the excitation, stabilization and control response of the system are studied in the stable mode. Autoresonant control is thoroughly investigated and output tracking is reported. The control developed provides the possibility of self-tuning and self-adaptation mechanisms that allow the screen machine to maintain a parametric resonant mode of oscillation under a wide range of uncertainty of mass and viscosit

Cryptosporidium in humans and animals - a One Health approach to prophylaxis

Cryptosporidium is a major cause of moderate to severe diarrhea in humans worldwide, second only to rotavirus. Due to the wide host range and environmental persistence of this parasite, cryptosporidiosis can be zoonotic and associated with foodborne and waterborne outbreaks. Currently, 31 species are recognized as valid and of these, Cryptosporidium hominis and Cryptosporidium parvum are responsible for the majority of infections in humans. The immune status of the host, both innate and adaptive immunity, has a major impact on the severity of the disease and its prognosis. Immunocompetent individuals typically experience self-limiting diarrhea and transient gastroenteritis lasting up to 2 weeks and recover without treatment, suggesting an efficient host anti-parasite immune response. Immunocompromised individuals can suffer from intractable diarrhea, which can be fatal. Effective drug treatments and vaccines are not yet available. As a result of this, the close cooperation and interaction between veterinarians, health physicians, environmental managers and public health operators is essential to properly control this disease. This review focuses on a One Health approach to prophylaxis, including the importance of understanding transmission routes for zoonotic Cryptosporidium species, improved sanitation and better risk management, improved detection, diagnosis and treatment and the prospect of an effective anti-cryptosporidial vaccine

The potential of fractional diagonal chromatography strategies for the enrichment of post-translational modifications

More than 450 post-translational modifications (PTMs) are known, however, currently only some of those can be enriched and analyzed from complex samples such as cell lysates. Therefore, we need additional methods and concepts to improve our understanding about the dynamic crosstalk of PTMs and the highly context-dependent regulation of protein function by so-called ‘PTM codes’. The mere focus on affinity-based enrichment techniques may not be sufficient to achieve this ambitious goal. However, the complementary use of two-dimensional chromatography-based strategies such as COFRADIC and ChaFRADIC might open new avenues for enriching a variety of so far inaccessible PTMs for large-scale proteome studies

Joint optimisation of inspection maintenance and spare parts provisioning: a comparative study of inventory policies using simulation and survey data

The demand for industrial plant spare parts is driven, at least in part, by maintenance requirements. It is therefore important to jointly optimise planned maintenance and the associated spare parts inventory using the most appropriate maintenance and replenishment policies. In this simulation-based study, we address this challenge in the context of the random failure of parts in service and the replacement of defective parts at inspections of period T. Inspections are modelled using the delay-time concept. A number of simultaneous periodic review and continuous review replenishment policies are compared. A paper making plant provides a real context for the presentation of our ideas. We survey practitioners working with such plant to collect real data that inform the values of parameters in the models. Our simulation results indicate that a periodic review policy with ordering that is twice as frequent as inspection is cost optimal in the context of the plant that we study. For the purpose of comparison, we also present and discuss the characteristics of the various policies considered