5MW Power Upgrade Studies of the ISIS TS1 Target

The increasing demand for neutron production at the ISIS neutron spallation source has motivated a study of an upgrade of the production target TS1. This study focuses on a 5 MW power upgrade and complete redesign of the ISIS TS1 spallation target, reflector and neutron moderators. The optimisation of the target-moderator arrangement was done in order to obtain the maximum neutron output per unit input power. In addition, at each step of this optimisation study, the heat load and thermal stresses were calculated to ensure the target can sustain the increase in the beam power

Spatial Heterogeneity of Climate Change Effects on Dominant Height of Larch Plantations in Northern and Northeastern China

Determining the response of dominant height growth to climate change is important for understanding adaption strategies. Based on 550 permanent plots from a national forest inventory and climate data across seven provinces and three climate zones, we developed a climate-sensitive dominant height growth model under a mixed-effects model framework. The mean temperature of the wettest quarter and precipitation of the wettest month were found to be statistically significant explanatory variables that markedly improved model performance. Generally, future climate change had a positive effect on stand dominant height in northern and northeastern China, but the effect showed high spatial variability linked to local climatic conditions. The range in dominant height difference between the current climate and three future BC-RCP scenarios would change from ´0.61 m to 1.75 m (´6.9% to 13.5%) during the period 2041–2060 and from ´1.17 m to 3.28 m (´9.1% to 41.0%) during the period 2061–2080 across provinces. The impacts of climate change on stand dominant height decreased as stand age increased. Forests in cold and warm temperate zones had a smaller decrease in dominant height, owing to climate change, compared with those in the mid temperate zone. Overall, future climate change could impact dominant height growth in northern and northeastern China. As spatial heterogeneity of climate change affects dominant height growth, locally specific mitigation measures should be considered in forest management

Adjacent Graph Based Vulnerability Assessment for Electrical Networks Considering Fault Adjacent Relationships Among Branches

Security issues related to vulnerability assessment in electrical networks are necessary for operators to identify the critical branches. At present, using complex network theory to assess the structural vulnerability of the electrical network is a popular method. However, the complex network theory cannot be comprehensively applicable to the operational vulnerability assessment of the electrical network because the network operation is closely dependent on the physical rules not only on the topological structure. To overcome the problem, an adjacent graph (AG) considering the topological, physical, and operational features of the electrical network is constructed to replace the original network. Through the AG, a branch importance index that considers both the importance of a branch and the fault adjacent relationships among branches is constructed to evaluate the electrical network vulnerability. The IEEE 118-bus system and the French grid are employed to validate the effectiveness of the proposed method.National Natural Science Foundation of China under Grant U1734202National Key Research and Development Plan of China under Grant 2017YFB1200802-12National Natural Science Foundation of China under Grant 51877181National Natural Science Foundation of China under Grant 61703345Chinese Academy of Sciences, under Grant 2018-2019-0

Study and optimisation of undulator-based polarised positron sources for linear colliders

High-energy accelerators play an important role in physics research. The International Linear Collider (ILC) and Compact Linear Collider (CLIC) are proposed future accelerators which will require of order 1014 positrons per second to fulfil their luminosity requirements. In addition, polarisation of the positron beam will increase the scope of the physics studies that can be performed using a linear collider. Production of large quantities of polarised positrons is one of the major challenges for the research, development and design of any future linear collider. A polarised positron source based on gamma rays produced by a high energy electron beam in a helical undulator has been selected as the baseline option for ILC. The design is relatively mature, and previous studies have shown that it should be capable of producing the required positron beam intensity and polarisation. We review the design using a range of analytical and simulation tools. We also consider, in more detail than in previous studies, two options for the design of a photon collimator that could be used to improve the positron polarisation. Although a Compton source is presently the baseline choice for the positron source for CLIC, an undulator-based scheme remains an option. We discuss the possibility of an undulator-based polarised positron source for CLIC Stage 1 (500 GeV centre of mass collision energy), and consider options for an undulator-based positron source in the upgrade to Stage 2 (3 TeV centre of mass collision energy). For both ILC and CLIC, energy deposition from the gamma rays striking the positron production target is a concern. For ILC, the energy density can be reduced by rotating the target at high speed; however, this raises concerns about the eddy currents induced by the strong field of the matching device. We report the results of experiments at Daresbury Laboratory to understand the eddy current effects, and to validate models for predicting the effects in the final system

Wave attenuation and focusing performance of parallel twin parabolic arc floating breakwaters

The hybrid system consisting of floating breakwater and point absorber wave energy converters provides a promising solution for shoreline protection and wave power generation. In the hybrid system, the breakwater plays an important role in protecting the sheltered area on the lee side and focusing high waves for better energy harvesting on the weather side. To improve the wave attenuation and focusing performance, a twin-breakwater consisting of a pair of parallel parabolic pontoons is proposed. Based on the potential flow theory of linear waves, the influences of gap width and connection method applied between the two pontoons are studied in the frequency domain, with an emphasis on the so-called critical mode around which both wave attenuation and focusing could be improved. Results show that the rigidly connected twin-breakwater is superior to the unconnected twin-breakwater with the same configuration in both wave attenuation and focusing. A second critical mode with lower frequency is also found under particular gap width, providing a potential for the defense of long waves. An optimal attenuation could be obtained by applying a proper gap width

A role of STAT3 in Rho GTPase-regulated cell migration and proliferation.

Rho family GTPases and STAT3 act as mediators of cytokine and growth factor signaling in a variety of cellular functions involved in inflammation, tumorigenesis, and development. In the course of searching for their functional connections, we found by using STAT3 knock-out mouse embryonic fibroblasts that RhoA, Rac1, and Cdc42 could cause nonspecific activation of STAT3 promoter-driven luciferase reporter in the absence of STAT3, raising concerns to a body of literature where STAT3 was associated with Rho GTPases based on the reporter system. We also found that although active RhoA, Rac1, and Cdc42 could all mediate Ser-727 and Tyr-705 phosphorylation and nuclear translocation of STAT3, the Rho GTPases were able to induce STAT3 activation independently of the interleukin-6 autocrine pathway, and active RhoA, Rac1, or Cdc42 could not form a stable complex with STAT3 as previously suggested, indicating an unappreciated mechanism of STAT3 activation by the Rho GTPases. The RhoA-induced STAT3 activation partly depended on Rho-associated kinase (ROK) and involved multiple effector signals as revealed by the examination of effector domain mutants of RhoA. Genetic deletion of STAT3 led to a loss of response to RhoA in myosin light chain phosphorylation and actin stress fiber induction but sensitized the cells to RhoA or ROK-stimulated cell migration. STAT3 was required for the RhoA-induced NF-kappaB and cyclin D1 transcription and was involved in NF-kappaB nuclear translocation. Furthermore, loss of STAT3 expression inhibited RhoA-promoted cell proliferation and blocked RhoA or ROK induced anchorage-independent growth. These phenotypic changes in STAT3-/- cells could be rescued by reconstituting STAT3 gene. Our studies carried out in STAT3 null cells demonstrate unambiguously that STAT3 represents an essential effector pathway of Rho GTPases in regulating multiple cellular functions including actin cytoskeleton reorganization, cell migration, gene activation, and proliferation

An Efficient Feature Extraction Method, Global Between Maximum and Local Within Minimum, and Its Applications

Feature extraction plays an important role in preprocessing procedure in dealing with small sample size problems. Considering the fact that LDA, LPP, and many other existing methods are confined to one case of the data set. To solve this problem, we propose an efficient method in this paper, named global between maximum and local within minimum. It not only considers the global structure of the data set, but also makes the best of the local geometry of the data set through dividing the data set into four domains. This method preserves relations of the nearest neighborhood, as well as demonstrates an excellent performance in classification. Superiority of the proposed method in this paper is manifested in many experiments on data visualization, face representative, and face recognition