Batch Scheduling with Proportional-Linear Deterioration and Outsourcing

We consider the bounded parallel-batch scheduling with proportional-linear deterioration and outsourcing, in which the actual processing time is pj=αj(A+Dt) or pj=αjt. A job is either accepted and processed in batches on a single machine by manufactures themselves or outsourced to the third party with a certain penalty having to be paid. The objective is to minimize the maximum completion time of the accepted jobs and the total penalty of the outsourced jobs. For the pj=αj(A+Dt) model, when all the jobs are released at time zero, we show that the problem is NP-hard and present a pseudo-polynomial time algorithm, respectively. For the pj=αjt model, when the jobs have distinct m (<n) release dates, we provide a dynamic programming algorithm, where n is the number of jobs

Thermal cycling behavior and hot corrosion performance of the plasma sprayed Er2Si2O7 coatings deposited on Cf/SiC composites

AbstractRare-earth based disilicates are promising coating materials for Cf/SiC composites. In this study, Er2Si2O7 coating was deposited on the Cf/SiC substrate by atmospheric plasma spraying using the solid-state reaction synthesized powders. Sintered Er2Si2O7 coupons derived from the synthesized powders were subjected to dilatometric studies showing the average value of 4.3ppm/°C for the coefficient of thermal expansion. The coated Cf/SiC coupons were thermally cycled between 400°C and 1500°C on a burner rig facility until failure of coating. Meanwhile, hot corrosion performance of the free standing plasma sprayed Er2Si2O7 coating coupon was evaluated by using molten vanadate salt with loading of 15mg/cm2 at 800°C. Analytical techniques such as X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy were applied to study the microstructural characteristics of the powders and coatings before and after thermal cycling and hot corrosion tests. Coatings’ degradation as a result of thermal cycling and hot corrosion tests was investigated in terms of microstructure and microchemistry transformations

Reaction Mechanism of ZrB2-ZrC Formation in Ni-Zr-B4C System Analyzed by Differential Scanning Calorimetry

The reaction mechanism of ZrB2-ZrC formation in a 30% Ni-Zr-B4C system under argon was revealed by using differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the reaction mechanism in the Ni-Zr-B4C system was complex. Initially, NixZry and NixBy intermetallics were formed via solid-state diffusion reactions between Ni, B4C and Zr. Then, the eutectic reaction between Ni2B and Ni4B3 lead to the formation of Ni-B liquid. The free C atoms dissolved into the Ni-B liquid to form a Ni-B-C ternary liquid, and then part of the Zr powder dissolved into the surrounding Ni-B-C ternary liquid to form Ni-Zr-B-C quaternary liquid. Finally, ZrB2 and ZrC formed and precipitated out of the saturated liquid. The eutectic liquid plays an important role during the formation of ZrB2-ZrC

Cryoballoon ablation for paroxysmal atrial fibrillation in a case of persistent left superior vena cava

Abstract Background Atrial fibrillation (AF) usually originates from pulmonary veins (PVs) but can also be caused by pulmonary veins outside, such as the coronary sinus (CS), the superior vena cava (SVC), and the ligament of Marshall. Case presentation A 69-year-old male with a history of palpitations for 10 years was referred to our institute because of its recurrence for half a day. A dynamic electrocardiogram revealed sinus rhythm (SR) and paroxysmal AF. Echocardiography demonstrated normal cardiac structure, and physical examination results were unremarkable. However, computed tomography angiography (CTA) showed a persistent left superior vena cava (LSVC) but no indication of thrombosis in the left atria. A cryoablation catheter was inserted into the PV. After the PV was successfully isolated, AF was still observed. After cardioversion was synchronized, SR was detected, but AF occurred again in less than a minute. Finally, we observed ectopic atrial electrical activity originating from the LSVC and successfully ablated it. Conclusions An LSVC may be a substrate for initiating or perpetuating atrial arrhythmia. Cryoballoon ablation can help treat AF originating from the LSVC

Reaction Behavior and Formation Mechanism of ZrB2 and ZrC from the Ni-Zr-B4C System during Self-Propagating High-Temperature Synthesis

Self-propagating high-temperature synthesis (SHS) is a good way to prepare ZrB2-ZrC/metal cermet composites. In this work, ZrB2-ZrC/Ni cermet composites with various Ni contents were successfully fabricated by SHS using the Ni-Zr-B4C system. The effects of Ni content and particle size of the B4C powder on the SHS reaction were investigated. The results indicated that with an increase in Ni content, the adiabatic temperature, maximum combustion temperature, ignition delay time, and ceramic particle size in the product all showed a gradually decreasing trend. The SHS products and the ignition of the SHS reactions were significantly dependent on the B4C particle size. The formation mechanism of ZrB2 and ZrC during SHS from the Ni-Zr-B4C system was proposed based on the combustion wave quenching experiment

Comparative Research on the Thermophysical Properties of Nano-Sized La2(Zr0.7Ce0.3)2O7 Synthesized by Different Routes

La2(Zr0.7Ce0.3)2O7 has been regarded as an ideal candidate for the next generation of thermal barrier coatings (TBCs) due to its prominent superiority. In this paper, the nano-sized La2(Zr0.7Ce0.3)2O7 was synthesized using two different synthetic routes: sol-gel and hydrothermal processes. Various techniques were utilized to assess the differences in the relevant thermophysical properties created by the different synthetic methods. According to the investigations, both samples exhibited pyrochlore structures with an excellent thermal stability. The sample synthesized via the hydrothermal method showed a more uniform particle size and morphology than that obtained through the sol-gel technique. The former also possessed a better sinter-resistance property, a more outstanding TEC (thermal expansion coefficient) and thermal conductivity, and a larger activation energy for crystal growth than the latter. The micro-strain of both samples showed an interesting change as the temperature increased, and 1200 &deg;C was the turning point. Additionally, relative mechanisms were discussed in detail

In situ synthesis and formation mechanism of ZrC and ZrB2 by combustion synthesis from the Co-Zr-B4C system

AbstractZrC-ZrB2-based composites were prepared by combustion synthesis (CS) reaction from 10wt.% to 50wt.% Co-Zr-B4C powder mixtures. With increasing Co contents, the particle sizes of near-spherical ZrC and platelet-like ZrB2 decreased from 1μm to 0.5μm and from 5μm to 2μm, respectively. In addition, the formation mechanism of ZrC and ZrB2 was explored by the phase transition and microstructure evolution on the combustion wave quenched sample in combination with differential scanning calorimeter analysis. The results showed that the production of ZrC was ascribed to the solid-solid reaction between Zr and C and the precipitation from the Co-Zr-B-C melt, while ZrB2 was prepared from the saturated liquid. The low B concentration in the Co-Zr-B-C liquid and high cooling rate during the CS process led to the presence of Co2B and ZrCo3B2 in the composites. The addition of Co in the Co-Zr-B4C system not only prevented ZrC and ZrB2 particulates from growing, but also promoted the occurrence of ZrC-ZrB2-forming reaction

Effects of Different Oxytocin and Temperature on Reproductive Activity in Nile tilapia (Oreochromis niloticus): Based on Sex Steroid Hormone and GtHR Gene Expression

Luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) belong to the gonadotropic hormone receptors (GtHR), which are highly expressed in fish gonads and participate in the regulation of fish reproductive activities. Fish gonadal development and gamete maturation are not only regulated by their BPG axis but also affected by natural environmental factors (such as temperature, salinity, pH, nutrients, light, etc.). Nile tilapia (Oreochromis niloticus) is a farmed fish with a short reproductive cycle, fast growth, and high economic value. To study the relationship between gonadotropic hormone receptors (GtHR) and the reproductive activity of Nile tilapia, different oxytocin injection experiments and different temperature treatment experiments were set up, and the expression changes of the GtHR gene in the gonads and the concentration changes of the estradiol (E2) in the female serum and testosterone (T) in the male serum were determined employing a quantitative RT-PCR assay and enzyme-linked immunosorbent assay (ELISA), respectively. After the injection of oxytocin, with the change of E2 in females and T in males, the FSHR showed an expression pattern of first increase, then decrease, and the LHR showed an expression pattern of first increase, then decrease, and finally increase in the gonads, and the expression level of FSHR and LHR in the injection group was significantly higher than that in the control group at multiple time points; in addition, the expression level of FSHR and LHR in the oxytocin-combination injection group was higher than that in the single injection group. During 28 days of treatment at different temperatures, the sex steroid hormones and GtHR genes also showed regular changes, and the relationship between each group was 28 &deg;C &gt; 32 &deg;C &gt; 24 &deg;C at most time points. According to the research results, it is speculated that FSHR and LHR play an important role in the development of Nile tilapia gonads and participate in the reproductive activities of Nile tilapia. By comparing and analyzing the changes in the sex steroid hormones and GtHR genes in each experimental group, it is speculated that different oxytocin injections could affect the expression of FSHR and LHR genes in Nile tilapia, and the combined effect of oxytocin was better than single oxytocin; the optimum temperature for the reproduction of Nile tilapia is between 28&ndash;32 &deg;C. This study provides a theoretical basis for further elucidating the physiological functions and molecular mechanisms of FSHR and LHR and also provides a reference for the research of reproductive regulation in Nile tilapia