A flexible and adaptive Simpler GMRES with deflated restarting for shifted linear systems

In this paper, two efficient iterative algorithms based on the simpler GMRES method are proposed for solving shifted linear systems. To make full use of the shifted structure, the proposed algorithms utilizing the deflated restarting strategy and flexible preconditioning can significantly reduce the number of matrix-vector products and the elapsed CPU time. Numerical experiments are reported to illustrate the performance and effectiveness of the proposed algorithms.Comment: 17 pages. 9 Tables, 1 figure; Newly update: add some new numerical results and correct some typos and syntax error

Process development of propionic acid production by fermentation

The fermentation kinetics of Propionibacterium thoenii strain P20 were studied with calcium alginate bead-immobilized cells without mass transfer limitations. The fermentation was found to be significantly affected by the end-product, propionic acid, in the medium. High levels of the acid not only inhibited cell growth, but also changed cell metabolism to produce more byproducts such as acetic, succinic and lactic acids. As a result, substrate consumption rate and propionic acid productivity and yield also decreased;Coupling liquid-liquid extraction of the acid with the fermentation, that is, extractive fermentation, alleviated the inhibitory effects. Solvent selection, based on partitioning and toxicity, was carried out among three solvent systems: Alamine°ler 304-1 in 2-octanol, 1-dodecanol, and Witcohol°ler 85 NF (oleyl alcohol). For each system, the acid loading per amine molecule decreased with increasing amine concentration; hence, an optimal amine concentration existed. The solvent toxicity to five strains of propionibacteria was determined. Strain P20 was the most solvent-resistant strain and Alamine 304-1 in Witcohol 85 NF was the only nontoxic solvent. Addition of vegetable oils to scavenge the toxic diluents was also able to reduce toxicity;Extractive fermentation was carried out with 40% (w/v) bead load of immobilized P20 cells and a hollow-fiber membrane extractor. By maintaining the propionic acid concentration at about 13 g/L, the yields of propionic and acetic acids were more than doubled compared to those of the nonextractive process. Higher acid productivities, an 80% reduction of base consumption for pH control, and solvent selectivity of propionic over acetic acid were also achieved;Vacuum distillation produced purified acids as the overheads and recyclable solvent as the bottoms. No solvent degradation occurred under the distillation conditions;Based on the experimental findings, economic evaluations of the extractive fermentation process on a 50,000-ton annual production scale were conducted. The process was modified to use whole-cell extraction with a mixer-settler extractor. This process suggested that economic feasibility could only be realized with favorable assumptions such as long-term bead usage, byproduct revenue, and inexpensive substrate

Multi-stage Suture Detection for Robot Assisted Anastomosis based on Deep Learning

In robotic surgery, task automation and learning from demonstration combined with human supervision is an emerging trend for many new surgical robot platforms. One such task is automated anastomosis, which requires bimanual needle handling and suture detection. Due to the complexity of the surgical environment and varying patient anatomies, reliable suture detection is difficult, which is further complicated by occlusion and thread topologies. In this paper, we propose a multi-stage framework for suture thread detection based on deep learning. Fully convolutional neural networks are used to obtain the initial detection and the overlapping status of suture thread, which are later fused with the original image to learn a gradient road map of the thread. Based on the gradient road map, multiple segments of the thread are extracted and linked to form the whole thread using a curvilinear structure detector. Experiments on two different types of sutures demonstrate the accuracy of the proposed framework.Comment: Submitted to ICRA 201

Gravitational resonances on f(R)f(R)-brane

In this paper, we investigate various $f(R)$-brane models and compare their gravitational resonance structures with the corresponding general relativity (GR)-branes. {Starting from some known GR-brane solutions}, we derive thick $f(R)$-brane solutions such that the metric, scalar field, and scalar potential coincide with those of the corresponding GR-branes. {We find that for branes generated by a single or several canonical scalar fields, there is no obvious distinction between the GR-branes and corresponding $f(R)$-branes in terms of gravitational resonance structure.} Then we discuss the branes generated by K-fields. In this case, there could exist huge differences between GR-branes and $f(R)$-branes.Comment: 17 pages, 14 figures, published versio

Time-Dependent Scalar Fields in Modified Gravities in a Stationary Spacetime

Most no-hair theorems involve the assumption that the scalar field is independent of time. Recently in [Phys. Rev. D90 (2014) 041501(R)] the existence of time-dependent scalar hair outside a stationary black hole in general relativity was ruled out. We generalize this work to modified gravities and non-minimally coupled scalar field with an additional assumption that the spacetime is axisymmetric. It is shown that in higher-order gravity such as metric $f(R)$ gravity the time-dependent scalar hair doesn't exist. While in Palatini $f(R)$ gravity and non-minimally coupled case the time-dependent scalar hair may exist.Comment: 6 pages, no figure