To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
The unmanned surface vehicle (USV) is deemed with significant potential to deal with the maritime search and rescue (SAR) missions. This paper investigates the path planning of the USV with SAR tasks, and proposes a novel algorithm based on combined convolutional neural network rapid-exploration random tree and improved artificial potential field (CRRT-IAPF). The proposed scheme can be divided into the global and the local path plannings. The rapid-exploration random tree (RRT) method is employed to generate the global path in the sea chart, which is further discriminated to be optimal or non-optimal through a well-trained convolutional neural network (CNN). The artificial potential field (APF) method is adopted to plan the local path in the environment with small obstacles and SAR task points. To facilitate the path convergence and avoid the oscillation, the potential field function is improved in a more efficient way. In addition, the evaluation functions of search success rate and rescue success rate are established to evaluate the completeness of SAR tasks. Through the simulation, it is verified that the proposed CRRT-IAPF scheme has the superiority over the others.
We investigate the natural oscillations of sessile drops with a central trapped bubble on a plane using linear potential flow theory, considering both free and pinned contact lines. The system is governed by the contact angle $\alpha$ and the ratio $\tau$ of inner to outer contact line radii. For bubble-containing (BC) hemispherical drops with free contact lines (referred to as free BC semi-drops), the modes mirror half of those in concentric spherical BC drops due to plane symmetry. These modes are labelled ‘plus’ (with greater inner surface deformation) and ‘minus’ (with greater outer surface deformation). As $\tau \to 0$, minus modes converge to those of bubble-free drops. Results show that varying $\alpha$ from $90^\circ$ or pinning the contact line in free BC semi-drops alters the topology of spectral lines, turning original crossings of spectral lines between minus and plus modes into avoided crossings. This shift causes minus and plus modes to form spectral trends with avoided crossings, maintaining their original spectral shapes. In an avoided crossing, two coupled modes cannot be classified as plus or minus due to their comparable inner and outer surface deformations, resulting in mode beating when both are excited, as confirmed by our direct numerical simulations. This study on the impact of inner bubbles on the spectrum may help in predicting bubble size in opaque sessile drops.
Zn is an important trace element involved in various biochemical processes in aquatic species. An 8-week rearing trial was thus conducted to investigate the effects of Zn on juvenile largemouth bass (Micropterus salmoides) by feeding seven diets, respectively, supplemented with no Zn (Con), 60 and 120 mg/kg inorganic Zn (Sul60 and Sul120), and 30, 60, 90 and 120 mg/kg organic Zn (Bio30, Bio60, Bio90 and Bio120). Sul120 and Bio120 groups showed significantly higher weight gain and specific growth rate than Con group, with Bio60 group obtaining the lowest viscerosomatic index and hepatosomatic index. 60 or 90 mg/kg organic Zn significantly facilitated whole body Zn retention. Up-regulation of hepatic superoxide dismutase, glutathione peroxidase and catalase activities and decline of malondialdehyde contents indicated augmented antioxidant capacities by organic Zn. Zn treatment also lowered plasma aminotransferase levels while promoting acid phosphatase activity and hepatic transcription levels of alp1, acp1 and lyz-c than deprivation of Zn. The alterations in whole body and liver crude lipid and plasma TAG contents illustrated the regulatory effect of Zn on lipid metabolism, which could be possibly attributed to the changes in hepatic expressions of acc1, pparγ, atgl and cpt1. These findings demonstrated the capabilities of Zn in potentiating growth and morphological performance, antioxidant capacity, immunity as well as regulating lipid metabolism in M. salmoides. Organic Zn could perform comparable effects at same or lower supplementation levels than inorganic Zn, suggesting its higher efficiency. 60 mg/kg supplementation of organic Zn could effectively cover the requirements of M. salmoides.
There are few studies on the intelligent guidance of unmanned sailboats, which should coordinate pluralistic tasks at sea in the nature of its maneuvring intractability. To ensure the algorithmic practicability, this paper proposes a path-following and collision-avoidance guidance approach of unmanned sailboats with total formulaic description. The risk-detecting mechanism is fabricated by setting a circular detecting zone and using the time to the closest point of approach. Then, the risk of collision, the path deviation, the speed loss, and the course loss can be judged by constructing the cost functions and applying the distance to closest point of approach. The optimized heading angle is deemed as the one minimizing the aggregate cost functions, which is sought by applying and improving the beetle antennae search (BAS) algorithm. In the proposed modified BAS, the searching step is redesigned to enhance the searching efficiency. To ensure the convergence of the real heading angle to the reference, the backstepping-based control law is fabricated for the high-order sailboat model and in the linear form. The control parameters are offline optimized through the modified BAS. Compared with the adaptive control, this controller can guarantee more computation simplicity and the optimized control performance. Finally, simulation corroborates that the sailboat can successfully complete path following and collision avoidance while encountering multiple static and moving obstacles under the proposed schemes.
We characterized the proteome profile of mid-lactation small-tailed Han (STH) and DairyMeade (DM) ovine milk in order to explore physiological variation and differences in milk traits between the two breeds. Methodology combined a tandem mass tag (TMT) proteomic approach with LC-MS/MS technology. A total of 656 proteins were identified in STH and DM ovine milk, of which 17and 29 proteins were significantly upregulated (P < 0.05) in STH and DM, respectively. Immune-related proteins and disease-related proteins were highly expressed in STH milk, whereas S100A2 and AEBP1 were highly expressed in DM milk, which had beneficial effects on mammary gland development and milk yield. Our results provide a theoretical basis for future breeding of dairy sheep.
We have previously bred Chinese local dairy sheep through grading up with local Small-Tailed Han (STH) sheep as female parent and DairyMeade (DM) sheep as male parent. In this research communication we characterize the whey protein profile of STH sheep and their offspring (F1, F2) to reveal physiological differences and variation in milk traits. A total of 1032 whey proteins were identified through tandem mass tag labeling (TMT) proteome profiling. Three proteins were significantly differentially abundant between F1 and STH milk, six between F2 and STH milk and five between F1 and F2 milk. In terms of differential changes between generations, WASHC4 and CUTA of F1 and Ig-like domain-containing protein of F2 milk were dominant whey proteins. Overall, the results showed that the whey protein profiles of different generations varied little. The crossbreeds of STH and DM sheep would be suitable for the development of the Chinese local sheep milk industry, and the F2 may be a better population for sheep milk production.
The 2Cr13/316L multilayered composite plates were fabricated by hot rolling with recycle heating step. The effect of rolling reductions on microstructure and properties was investigated. The 2Cr13 layer consists of martensite and lath ferrite, but the middle layer has less ferrite than both sides. The content and grains of ferrite increase with the increase of the reduction and number of reheating, which leads to a decrease in the hardness of the 2Cr13 layer. The hardness of the 2Cr13 layer is determined by the volume ratio of martensite and ferrite. Tensile strength of the specimens with the rolling reduction of 72% and 82% reached 815.8 MPa and 763.4 MPa, while elongations were 20% and 20.8%, respectively. With the increase of the rolling reduction, the fracture mode also changed from cleavage fracture to dimple fracture. There were no cracks and delamination when the 2Cr13/316L composite plate bent to 130° and 180°, which indicated better interfacial bonding.
To date, most antibodies from combinatorial libraries have been selected purely on the basis of binding. However, new methods now allow selection on the basis of function in animal cells. These selected agonist antibodies have given new insights into the important problem of signal transduction. Remarkably, when some antibodies bind to a given receptor they induce a cell fate that is different than that induced by the natural agonist to the same receptor. The fact that receptors can be functionally pleiotropic may yield new insights into the important problem of signal transduction.
In order to improve the utilisation and performance of anode catalysts in direct methanol fuel cells (DMFCs), functionalised multi-walled carbon nanotubes (MWCNTs) are used as a support for palladium (Pd) nanoparticles synthesised by photochemical reduction. MWCNTs are modified by methylene blue (MB) under ultraviolet light (fuv-MWCNTs), and then Pd nanoparticles are assembled on the fuv-MWCNTs to form composites (Pd/fuv-MWCNTs). The method is green, simple and does not destroy the pristine structure of the MWCNTs. The morphology and structure of prepared composites are characterised by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that Pd nanoparticles with face-centred cubic crystal structure are about 3.9 nm in size, and are uniformly dispersed on the surface of fuv-MWCNTs. X-ray photoelectron spectroscopy (XPS) reveals that N-containing and S-containing groups exist in fuv-MWCNTs. These groups might be active sites for assembly of Pd nanoparticles on the surface of fuv-MWCNTs, and can modify the electronic structure of Pd nanoparticles. Electrochemical experiments indicate that the prepared Pd/fuv-MWCNTs catalyst exhibits excellent catalytic performance. The catalytic activity of Pd/fuv-MWCNTs is 1.94 times higher than that of commercial Pd/C for methanol oxidation in alkaline solution. It indicates that UV irradiation can facilitate MB to functionalise MWCNTs, reinforce the modification of the electronic structure of Pd, and enhance the catalytic activity of Pd/fuv-MWCNTs.
Lithium ion battery cathode material LiNi0.8Co0.15Al0.05O2 cathode has successfully prepared by co-precipitation. CeO2 surface modification has improved LiNi0.80Co0.15Al0.05O2 electrochemical performance use sol-gel method and subsequent heat treatment at 600 °C for 5 h. Different to other conventional coating material, CeO2 coating layer can not only inhibit the reaction of the electrode and the electrolyte, but also can reduce the impedance of electron transfer due to its high conductivity, and inhibit the production of Ni2+ because of its high oxidation. The surface-modified and pristine LiNi0.80Co0.15Al0.05O2 powders are characterized by XRD, SEM, TEM, XPS, CV and DSC. When CeO2 coating is 0.02% (mole ratio), contrast to pristine NCA, the CeO2-coated NCA cathode exhibits no decrease in its initial specific capacity of 184 mAh g −1 (at 0.2 C) and excellent capacity retention (86% of its initial capacity at 1 C) between 2.75 and 4.3 V after 100 cycles. The results indicate that the CeO2 surface treatment should be an effective way to improve cycle properties due to CeO2 inhibit the electrodes and the electrolyte side effects.
A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg−1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.
A series of uranium-containing gadolinium zirconate samples have been fabricated at 1723 K in air. X-ray diffraction and Raman spectroscopy have confirmed pyrochlore or defect fluorite structures, while diffuse reflectance, X-ray absorption near edge structure and X-ray photoelectron spectroscopies indicate a predominantly U6+ oxidation state, even when Ca2+ was added to charge balance for U4+. The results demonstrate the potential of gadolinium zirconates as host materials for actinides.
In this paper we present two versions of the central localdiscontinuous Galerkin (LDG) method on overlapping cellsfor solving diffusion equations, and provide theirstability analysis and error estimates for the linear heat equation.A comparisonbetween the traditional LDG method ona single mesh and the two versions of the central LDGmethod on overlapping cells is also made.Numerical experiments are provided to validate the quantitativeconclusions from the analysis and to support conclusions forgeneral polynomial degrees.
We prove stability and derive error estimates for the recently introduced central discontinuous Galerkin method, in the context of linear hyperbolic equations with possibly discontinuous solutions. A comparison between the centraldiscontinuous Galerkin method and the regular discontinuousGalerkin method in this context is also made.Numerical experiments are provided to validate the quantitativeconclusions from the analysis.
We propose a capital allocation method for insurance companies. The amount of capital is directly related to the default risk. The expected value of default can be distributed among the liabilities based on the rule of asset payoff at the time of default. We derive a capital allocation scheme from this allocation of the expected default. Assets, liabilities, and other risky items on the balance sheet are treated in a uniform framework. The insurer’s capital is allocated among all these risk contributors. The allocated capitals are given in closed-form formulas, which have straightforward interpretations and are easy to compute. Connections with other allocation methods are also discussed.
Hot isostatically pressed (HIPed) glass-ceramics for the immobilization of uranium-rich intermediate-level wastes and Hanford K-basin sludges were designed. These were based on pyrochlore-structured Ca(1-x)U(1+y)Ti2O7 in glass, together with minor crystalline phases. Detailed microstructural, diffraction and spectroscopic characterization of selected glass-ceramic samples has been performed, and chemical durability is adequate, as measured by both MCC-1 and PCT-B leach tests.
Calcined high-level radioactive waste (HLW) stored at the Idaho National Laboratory (INL) will eventually be immobilised in a suitable wasteform before disposal. A tailored glass-ceramic wasteform, produced by hot isostatic pressing in stainless steel (SS) cans, has been developed at ANSTO as a cost-saving alternative to glass which would improve waste loading and density, and reduce waste volume. We have studied the SS/wasteform interactions under HIPing conditions to understand whether such interactions would have any detrimental effect on long-term wasteform stability. This has been demonstrated by carrying out aqueous durability tests, under near-neutral and alkaline conditions, on the wasteform at the interaction layer, and on the wasteform distal to this reaction edge. Reaction during HIPing resulted in Cr diffusion from the can wall into the wasteform, however without any detectable detrimental impact on the HIP can or the aqueous durability of the wasteform.
We study the Hausdorff dimension of invariantsets for expanding maps and that of hyperbolic sets on unstablemanifolds. Upper bounds for the Hausdorff dimension are given in termsof topological pressure, or topological entropy and Lyapunovexponents.
We present results of current measurements on the super-sensitive mini-cyclotron as an accelerator mass spectrometer, successfully developed at Shanghai Institute of Nuclear Research (SINR). We describe new ideas and unique techniques adopted for increasing the transmission efficiency in the injection, acceleration and extraction region, for eliminating various backgrounds and for improving the precision of 14C analysis, which have led to the breakthrough of our Shanghai Mini-Cyclotron Accelerator Mass Spectrometry project. We also discuss further development of the prototype facility.
A series of cast Ni3Al-base alloys with the addition of alloying elements, such as Hf, Zr, Ti, Nb etc., have been studied, in which the total amount of Al and alloying elements substituting for Al was controlled in the range of 18 to 23 at%. It was found the alloying elements change remarkably the morphology, distribution and amount of γ phase as well as the morphology and size of primary γ′ intermetallic compound. The size of primary γ′ can be decreased to micron order. The brittle γ′-γ′ boundary (refer to primary γ′) can be substituted by tough γ′-γ-γ′ boundary. As a result, the mechanical properties of the cast Ni3Al-base alloys, especially high temperature ductility, can be enhanced. In addition, the effect of Cr is discussed when tested in air environment, and considered that chromium addition is not very effective to improve the high temperature embrittlement.
Recommend this
Email your librarian or administrator to recommend adding this to your organisation's collection.